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In this study, we investigate the effects of doping with ∼10 at% of Si, Al, Sn, and Bi on the atomic order, microstructure, and magnetic properties of CoMnSb samples prepared using the arc-melting method. X-ray diffraction, scanning electron microscopy, and magnetometry techniques were employed to derive the structural and magnetic parameters. The samples demonstrate a superstructure with an Fm -3 m space group. They exhibit a saturation moment of 3.71–4.71 μ B per formula unit at 5 K and a Curie temperature ranging from 474 to 507 K. Rietveld refinement performed on the XRD data revealed a possible occupation of magnetic atoms in the vacant 32 f (x ', x ', x ') sites and atomic swapping, both of which may affect the magnitudes of the magnetic moment and Curie temperature. The electrical measurement results show that the grain boundaries and voids govern the conductivity of the samples. The spin polarization of the Si-doped sample was determined based on the grain-boundary magnetoresistance effect, which showed that this sample has a high degree of atomic order, consistent with the low magnetic moment, Curie temperature, and lattice constant. [ABSTRACT FROM AUTHOR]

Heusler alloys based on 4d-elements are relatively less explored though they are known to host interesting electronic/magnetic properties useful for future spintronics applications. Here, we report a comparative study of the structural and magnetic properties of FeRuVSi (FRVS) and FeRuVGe (FRVG) using experimental and theoretical tools. Magneto-transport measurements have also been carried out to probe the role of magnetism on their transport behaviour. Room temperature (T) X-ray diffraction data reveals cubic crystal structure (space group No. 216) with B 2 type antisite disorder between Fe and Ru sites in both the alloys. They show ferromagnetic behaviour below the Curie temperature (T C) 84 K for FeRuVSi and 57 K for FeRuVGe respectively. The field dependence of magnetization at low-T shows saturating (nearly saturating) behaviour for FRVS (FRVG). Transport measurements show metallic behaviour with a sharp reduction in the resistivity near T C. Ab-initio calculations predict nearly half metallic behaviour with ∼ 87 % and ∼ 89 % spin polarization for FRVS and FRVG in their ordered states. The inclusion of antisite disorder changes the magnetic configuration, leading to a visible decrease in the magnetic moment and spin polarization. The calculated net moment and the transport properties agree fairly well with those observed experimentally. These results confirm the importance of disorder in determining the intrinsic properties of these alloys. Such combined studies help in the identification of more novel quantum materials suitable for future spintronic applications. ● We present a comparative study of the magnetic, transport, and electronic properties of FeRuVZ (Z = Si, Ge) Heusler alloys. ● Disorder increases the symmetry of the FeRuVSi Heusler alloy to L 2 1 type, higher than that in FeRuVGe. ● The magnetization goes from saturating to nearly saturating behaviour when Si is changed to Ge. ● High spin polarization and nearly half metallic behaviour in the ordered state in both the alloys. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the electronic, magnetic, and optical properties of scandium based ternary oxides perovskite YScO 3 (Y = Ni, Pd, Pt). We employ the Tran and Blaha modified Becke-Johnson approximation to calculate spin polarization using the density functional theory. Based on the formation energy, we found that our materials are thermodynamically stable (−0.76 eV, −1.3 eV and −1.65 eV for NiScO 3 , PdScO 3 and PtScO 3 , respectively). The densities of states and spin polarized band structures for spin up (↑) and spin down (↓) channels reveal the half-metallic nature for all studied compounds with Ni/Pd/Pt-d orbitals playing a major role in the valence band. Additionally, all perovskites exhibit ferromagnetic behavior with magnetic moments approximately equal to 3 μ B. Moreover, we calculate several optical parameters such as the dielectric constants, refractive index, reflectivity, extinction and absorption coefficients for these compounds. The results suggest that these perovskites might be promising candidates for optical and spintronic devices. • YScO3 (Y = Ni, Pd, and Pt) are thermodynamically stable. • Exhibits half-metallic ferromagnetism with 100% spin polarization. • The structural, electronic, magnetic, and optical properties were investigated using density functional theory. • Promising candidates for spintronic applications. [ABSTRACT FROM AUTHOR]

This study employs density functional theory (DFT) using Wien2k to comprehensively analyze the essential properties of two half-Heusler alloys, KCrSi and KCrGe. Our findings demonstrate that the ferromagnetic Type 2 configuration exhibits superior stability over non-magnetic and antiferromagnetic states for all KCrZ (Z = Si, Ge) alloys. These alloys exhibit complete spin polarization and half-metallic character, with calculated magnetic moments of 3 μB for both KCrSi and KCrGe. The Curie temperature (T C) is determined using the mean field approximation. Mechanical stability is assessed through second-order elastic constants (SOECs), and electronic properties are analyzed using local spin density approximation (LSDA), Perdew-Burke Generalized Gradient Approximation (PBE-GGA), and Tran-Blaha modified Becke-Johnson (TB-mBJ) schemes, confirming the retention of the half-metallic nature. The negative enthalpy of formation (ΔH) suggests material stability. The use of semi-classical Boltzmann theory, incorporated through the sophisticated scheme of BoltzTraP, explores transport coefficients. High pressures and temperature discrepancies in thermodynamics are considered by implementing the quasi-harmonic Debye approximation to illustrate stability. Finally, optical properties are summarized to assess the applicability of this alloy for optoelectronic applications. The overall characteristics of these particular alloys suggest potential applications in sustainable thermoelectric and optoelectronic features. • The stability in cubic structure is established with the help of structural optimization, and mechanical stability criteria. • The high Seeback coefficient and low thermal conductivity yield a high figure of merit ZT at 900 K. • The alloy has potential applications in thermoelectric technology and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions are the core component of spintronic devices, and good magnetic tunnel junctions require high tunnel resistance, which is determined by the spin polarization of the thin films of ferromagnetic layers that make up their structure. Therefore, the design of ferromagnetic films with high spin polarization is a current research hotspot in this field. In the current study, we taken the half-metallic CrYCoAl as an object, and studied the influence of surface effect on the half-metallic behavior. Especially, we constructed the CrYCoAl (100), (110), and (111) surfaces to study their stability, electronic and magnetic properties. Results show that the YY and YAl (100) surfaces, and Co (111) surface retain the half-metallic behavior and structural stability of bulk, which provide a basis for CrYCoAl application as a thin films in magnetic tunnel junctions thus, they are likely to be used in the spintronic devices. • Stability of CrYCoAl (100), (110) and (111) surfaces are estimated by their phase diagrams. • Atomic relaxation and surface roughness are discussed. • Electronic and magnetic properties of CrYCoAl (100), (110) and (111) surfaces are studied. • The YAl and YY (100), and Co (111) termination surfaces maintain the half-metallic nature of bulk CrYCoAl. [ABSTRACT FROM AUTHOR]

• Highly ordered L2 1 type heusler alloy film on cu substrate. • Near stoichiometric Co 2 FeSn films by electrodeposition. • High magnetic moment, high T C and high effective anisotropy films. • Co 2 FeSn films (320 nm −1400 nm thick) with high crystalline order. • Minority band gap close (∼0.05 eV) to fermi level. Co 2 FeSn films have been electrochemically deposited on polycrystalline Cu substrates in potentiostatic mode. Processed films with thicknesses of 320 nm, 780 nm, and 1400 nm exhibited highly ordered L2 1 type crystal structure with saturation magnetizations of 1023.38 kA/m (5.08 ± 0.04 μ B /f.u.), 1035.31 kA/m (5.14 ± 0.04 μ B /f.u.) and 1044.34 kA/m (5.18 ± 0.04 μ B /f.u.) at 5 K and 965.00 kA/m (4.79 ± 0.04 μ B /f.u.), 967.75 kA/m (4.81 ± 0.04 μ B /f.u.), and 1003.52 kA/m (4.97 ± 0.04 μ B /f.u.) at 300 K, respectively. The soft ferromagnetic films possess coercivity of ∼ 15.92 kA/m (200 Oe) with a high effective anisotropy constant of ∼ 105 J/m3. Thermo-magnetization measurements yielded high Curie temperatures of 995 K, 1005 K, and 1123 K for films of thicknesses 320 nm, 780 nm, and 1400 nm, respectively. Tailoring the thickness from 320 to 1400 nm could be achieved by merely varying the electrodeposition time without appreciable departure from chemical stoichiometry or compromise in crystalline order or magnetic properties. This establishes a methodology to prepare high quality L2 1 ordered Co 2 FeSn films with a few hundred nanometers thickness by electrodeposition. Electrodeposited Co 2 FeSn films with high magnetic moment, high K e f f value, and high Curie temperature are potential candidates for fabricating nanomagnetic devices. [ABSTRACT FROM AUTHOR]

• First-principles calculations performed for XA and L2 1 phases across X 2 FeAl series. • The degree of d-d orbital hybridization drives magnetic and electronic properties. • Increasing X-site valence electron counts result in increased hybridization levels. • Orbital hybridization trends must be considered when predicting material properties. First-principles calculations are performed for full (L2 1) and inverse (XA) Heusler compounds X 2 FeAl, where X comprise a range of 3d (Sc, Ti, V, Cr), 4d (Y, Zr, Nb, Mo), and 5d (Hf, Ta, W) early and middle column transition metal elements. The formation energy difference between full and inverse phase and the degree of d-d orbital hybridization with increasing total valence electron count are shown to drive the magnetic properties (total and atomic magnetic moments, spin polarization) and electronic properties (band structure and projected density of states) of the material system. Specifically, X-site atomic magnetic moments take on increasingly Fe character with increasing valence electron count, in both full and inverse Heusler phases. This can be explained by changes on the degree of d-d hybridization between X- and Fe-site d orbitals. Synchronized energy shifts in the PDOS of the X- and Y-sites (Fe) across each of the full and inverse Heusler series provide us insight to controlling spin polarization via composition. This work demonstrates the need to holistically study the thermodynamic phase stability, magnetic moments, and spin polarization of Heusler alloys, in the framework of anti-site disorder and in a wider compositional context. The end goal of this study is to benefit the mapping of experimental results in search of a specific property, by providing a methodology for extrapolating properties based on experimental or theoretical results. [ABSTRACT FROM AUTHOR]

The magnesium based spinel chalcogenides are outstanding materials for spintronic technology and energy applications. Herein, the modified Becke Johnson potential (TB-mBJ) was employed to investigate the electrical, ferromagnetism, and thermoelectric properties of MgDy 2 (S/Se) 4 spinels comprehensively. The energy emitted during optimization as well as formation energy has both been used to demonstrate the stability of the cubic phase. The density of states, Curie temperature, exchange coupling, and spin polarization are elaborated to address the nature of ferromagnetism. Further, half metallic ferromagnetism is studied in terms of hybridization, exchange energies, and exchange constants. In contrast to the clustering effect of the internal magnetic of Dy atoms in the structure, the lowering of Dy's magnetic moment and its transferring on Mg, and S/Se sites demonstrate that the ferromagnetism is caused by the exchange of electron spin. Furthermore, thermoelectric properties were studied and various thermoelectric parameters such as electrical and thermal conductivities, Seebeck coefficient (S), and power factor (PF) of the examined spinels have been determined. • Above room temperature ferromagnetism, and spintronic applications. • Quantum spin of electrons dominant the charge with multifuctional properties. • Exchange mechanism certifies the ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism and 100 % spin polarization. • Large value of electrical conductivity and ultralow low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

In this theoretical study, we investigate novel quaternary Heusler Fe–Rh–Mn–Al alloys in the X-type structure with different types of atomic ordering in the unit cell within the spin-polarized density functional calculations. The calculations showed that the 24 possible configurations converge to the 6 nonequivalent solutions. Two types of atomic ordering with the lowest total energy Fe(4c)Rh(4d)Al(4b)Mn(4a) and Mn(4c)Al(4d)Fe(4b)Rh(4a) are half-metallic ferrimagnets in which the spin polarization at the Fermi level is close to 100 %. However, no gap is open in the majority spin projection. The following values of the total magnetic moments for these alloys were obtained: 3.01 and 3.19 μ B /f.u., respectively. In the other types of atomic ordering, the half-metallic state is not formed. In FeAlRhMn, the magnetic moment on the manganese ion compensates for the moments on the other ions, and the total moment is close to zero. In the types (MnFeRhAl, AlRhFeMn) of atomic ordering with high energies, the metallic state is also realized, and the magnetic moments on the ions are ordered ferrimagnetically. In this work, we analyzed novel quaternary alloys with different types of atomic ordering motivated by the demand for alloys with a high spin polarization, among which the FeRhAlMn and MnAlFeRh alloys were found. Both with a half-metallic ferrimagnetic state and the lowest total energy among these alloys with the same chemical composition, which indicates the stability of the half-metallic state. The other types of atomic ordering are less energetically favorable, those alloys are ferrimagnetic metals with the low spin polarization. Taking into account the half-metallic state and high spin polarization, the quaternary FeRhAlMn and MnAlFeRh alloys have prospects for use in spintronic devices. [ABSTRACT FROM AUTHOR]

• The half metallicity of NiVTiZn could be maintained when uniaxial strain ratio increases from −7.28% to 9.59% and when c / a ratio ranges from 0.92 to 1.06. • The 100% spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures. • The effect of various disorder on mechanical and thermodynamic properties is also studied in detail. The influence of atomic disorder on electronic, mechanical and thermodynamic properties of equiatomic quaternary all- d metal Heusler alloy NiVTiZn is studied by employing the first-principles calculations. The ground state of NiVTiZn is confirmed to be α -type structure with ferromagnetic nature, the calculated spin down energy gap and equilibrium lattice constant is ∼0.7 eV and 6.048 Å, respectively. The half metallicity could be maintained when uniaxial strain ratio increases from −7.28 % to 9.59 % and when c / a ratio ranges from 0.92 to 1.06, showing a robust half metallicity against the strain effect and tetragonal distortion. Six types of atomic swap disorder and twelve types of atomic antisite disorder are proposed. The V(Ni) and V(Zn) antisite disorders as well as V-Ni and V-Zn swap disorders are the most favorable owing to their negative formation energies. The 100 % spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures although the width of band gap suffers contraction. The spin polarization of Ni(V), Ni(Zn), V(Zn) and Zn(Ni) disordered structures is also larger than 80 %. In addition, the effect of various disorder on mechanical and thermodynamic properties is also studied in detail. [ABSTRACT FROM AUTHOR]

Spintronic is the developing technology which probes the properties of quantum devices with spin of electrons which reduce the size and enhance its speed. Therefore, here the role of 5d electrons and thermoelectric characteristics of double perovskites (DPs) K 2 ZCl/Br 6 (Z = Ta, W, Re) elaborated comprehensively by density functional theory (DFT). The Heisenberg model spin polarization density (SP) has been applied to evaluate the Curie temperature (T c) and spin polarization factor. The tolerance factor (t F) and formation energy (ΔH) have been calculated to confirm the stability of structures. Ferromagnetism has been discussed in terms of spin polarization, crystal field energy (Δ CF) and exchange energies (Δ(d), Δ(pd)). The double exchange mechanism, and exchange constants ensure the role of electrons spin in ferromagnetism instead of segregation of transition metal ions. The transferring of magnetic moments of transitions metals to nonmagnetic sites (K, Cl, Br) show the exchange of spin of electrons and integer values of total magnetic moment show 100 % spin polarization. Finally, the transport properties are studied in standings of electrical and thermal conductivities. The large value of Seebeck coefficient and power factor ensure the importance of studied DPs for thermoelectric generators. • Spintronic and energy harvesting applications. • Large value of Curie temperature and high spin polarization. • The ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism evidence complete spin polarization. • Ultralow low values of thermal conductivity and Large power factor. [ABSTRACT FROM AUTHOR]

[Display omitted] • First-principles analysis to determine the impact of lanthanum (La) at the A-site and X (Ni, Co, Mn, Ti) at the B-site as mono- and co-dopants on spin-polarized electronic, structure and magnetic characteristics of Cubic BFO structure. • Calculations carried out in the Cambridge Serial Total Energy Package (CASTEP) code by using ultra-soft pseudopotential (USP) under GGA and LDA + U functionals. • The substitution of La and X atoms alters the spin-polarized electronic and dielectric characteristics of BFO, leading to an increase in the density of states (DOS) around the Fermi level. • LaCo and LaNi have shown have high spin polarizations of 87.08% and 82.20%. • Extremely low switching energies of 0.52 aJ and 0.72 aJ, respectively, observed for LaCo and LaNi co-doped BFO systems. In spintronic technology, bismuth ferrite BiFeO 3 (BFO) is a potential multiferroic material for multiferroic capacitor application. In present study, the impact of transition metals X = Co, Ni, Mn, Ti at the Fe-site and rare earth element lanthanum (La) at the Bi-site is investigated using DFT calculation in order to improve the structural stability, spin polarized electronic, and dielectric properties of bismuth ferrite for switching energy of multiferroic capacitor applications. The calculations are carried out in the Cambridge Serial Total Energy Package (CASTEP) code by using ultra-soft pseudopotential (USP). The substitution of La and X atoms alters the spin-polarized electronic and dielectric characteristics of BFO, leading to an increase in the density of states (DOS) around the Fermi level. The observed descending order of the structure stability of co-doped BFO is given as: LaCo > LaNi > LaMn co-doped BFO system. LaCo and LaNi co-substituted systems have shown high spin polarizations of 87.08 % and 82.20 % respectively. Low switching energies of 0.52 aJ and 0.72 aJ, respectively have been observed for LaCo and LaNi co-doped BFO systems for multiferroic RAM capacitor applications. [ABSTRACT FROM AUTHOR]

We investigated the degree of B2 order (S B2) of 4-10 nm-thick polycrystalline Co 2 (Mn 0.6 Fe 0.4)Ge (CMFG) Heusler alloy films using anomalous X-ray diffraction (AXRD) and its correlation to the magnitude of current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) effect. We found that S B2 of the CMFG films is degraded for the film thickness below 6 nm, which is an issue for practical applications of CPP-GMR devices such as read head sensors of hard disk drives. Since S B2 has a thickness-dependence, the bulk spin polarization (β) of the CMFG layers is also expected to vary depending on the thickness; thus, the deduction of β using the Valet-Fert model, where β is assumed to be thickness-independent, is not valid for these CPP-GMR devices. Image, graphical abstract [ABSTRACT FROM AUTHOR]

[Display omitted] The quaternary Heusler alloys with composition LiAEFeSb have been studied in this manuscript (AE = Alkaline Earth elements Be, Mg, Ca, Sr and Ba) for their potential applications in spintronics. All the investigations have been performed by employing density functional theory. A systematic comparison of results obtained within local density approximation (LDA) and the generalized gradient approximation (GGA) done. Our calculations reveal that all the studied alloys have lowest energy in type-I arrangement of basis and exhibit interesting electronic and magnetic properties. All the alloys exhibit a stable ferromagnetic ground state. Fixed spin moment calculations rule out existence of any other local magnetic minima. The phonon dispersions show that all the alloys except LiBeFeSb are dynamically stable. Notably, LiSrFeSb and LiBaFeSb exhibit half-metallic electronic band structure and 100 % spin polarization making them suitable choice for promising spintronic applications such as spin filter and detectors. [ABSTRACT FROM AUTHOR]

• DFT calculations were used to study the magnetic properties of the Fe 2 MnAs alloy. • The influence of point defects on these properties were investigated. • The formation energy, density of states, and magnetic moments, were computed. • The contraction of the lattice enhance the spin polarization of the Fe 2 MnAs alloy. • The defects of Mn As , Mn ↔ As, V As , and V Mn exhibit 100% spin polarization. First-principles calculations within the framework of the density functional theory were conducted using the FP-LAPW method to investigate the electronic and magnetic properties of the Full-Heusler Fe 2 MnAs alloy. The study encompassed the examination of its perfect structure as well as the variation of lattice constants around the ground state. The negative value of the calculated formation energy suggests that the alloy may form spontaneously. From a magnetic perspective, Fe 2 MnAs exhibit a ferromagnetic order. The alloy also shows a high spin-polarization that may be increased, transforming the alloy into a half-metal, with the contraction of the lattice constant. Furthermore, the investigation delved into the effect of point defect formation. The calculated formation energies for vacancies, antisite, and exchange defects suggest the likely occurrence of some of these defects within the Fe 2 MnAs compound. Significantly, certain defects contribute to the spin-polarization of the alloy, effectively rendering it a fully half-metallic material. [ABSTRACT FROM AUTHOR]

• The effect of 3d TM dopants (12.5% doping concentration) in BiCoO 3 having C-type AFM arrangement has been studied using first principle calculation to study the structural, electronic and magnetic properties. • The defect states are introduced due to presence of 3d TM dopants in BCO. • The PDOS reveal that V, Ni and Zn doped BCO exhibit half metallic characteristics. • The net magnetization was found to arise due to TM doping at Co site which may be attributed to the uncompensated Co spins and is mainly localized on the TM dopant. • SSP model was used to explain the net magnetization in the system due to 3d TM dopants in BCO system. • Ti doped BCO system found to be most stable due to lowest formation energy as compared to other 3d TM doped BCO system. In this paper, the influence of 3d transition metal (TM) dopants in BiCoO 3 (BCO) having C-type antiferromagnetism has been studied using first principles calculation. The value of c/a ratio is found to improve for Sc, V, Mn, Fe, Ni, Cu and Zn doping in BCO which indicates an increase in the tetragonality ratio upon introduction of these dopants in BCO. The formation energy calculations pointed out that it is easier to incorporate the TM atoms having number of d atoms lesser than that of Co (d < 7) in BCO. The electronic, and magnetic properties were studied and it was found that the electron/hole traps are introduced due to the presence of 3d TM dopant in BCO. The partial density of states reveal that V, Ni and Zn doped BCO exhibit half metallic characteristics with a lower band gap value among the other TM doped BCO systems. It was interesting to note that the presence of states in both spins at Fermi level due to Cu doping leads to a transition of BCO towards metallic behaviour in contrast to pure BCO having a clear band gap of 1.77 eV. The net magnetization was found to arise due to TM doping at Co site which may be attributed to the uncompensated Co spins and is mainly localized on the TM dopant. Successive spin polarization model (SSP model) was used to explain the net magnetization in the system due to 3d TM dopants in BCO system. The electron localization function plots also reveal that for d < 5 the electrons are localised near the TM metal ions and for d > 5 the localization impacts the near neighbouring Co ions. From this study, it is suggested that the magnetic and electronic properties of BCO system, can be tuned by 3d TM doping which has vast potential in photovoltaic and magneto-electric applications. [ABSTRACT FROM AUTHOR]

The double perovskites have outstanding properties for spintronic devices as they are stable, non-toxic, and accomplish the spin polarization. This article studies the function of 5d-electrons of Ta, W, Re and Os to regulate the magnetic properties of Sr 2 CrXO 6. The tolerance factors and formation energies confirm the stability of the structures and the thermodynamics. The half-metallic ferromagnetic nature is found by analyzing the density of states and band structures described by the double exchange model, exchange energy, and exchange constants. According calculations, ferromagnetism is induced by the electron spin due to hybridization process, magnetic moments, exchange energies, and crystal field energy. The thermoelectric applications are further explored by computing and discussing the thermal and electrical conductivities, and Seebeck coefficients. The power factor has also been elaborated for the performance of studied DPs. • Ferromagnetism at high temperature, and spintronic applications. • Spin of electrons operates the devices with multifuctional properties. • Role of 5d electrons and exchange of energies. • Half metallic ferromagnetism and complete spin polarization. • Ultralow low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

We have grown thin films of Co 2 TiSi (CTS) Heusler alloy on n-type Si (100) at different substrate temperatures by electron beam evaporator under a high vacuum. The structural, magnetic, and electric characterizations were carried out and found a strong correlation between the properties and the growth temperatures of the samples. The crystallinity and magnetic moment both were significantly improved with increasing growth temperatures from room temperature to 400 °C. The saturation magnetization of 1.85 µ B at 10 K is close to the theoretical Slater–Pauling value. A large value of spin wave stiffness constant (D = 7.2 meV- nm2) of CTS film manifests the robustness of magnetization. The temperature-dependent longitudinal resistivity demonstrated different scattering phenomenon like weak localization, electron-magnon, electron-election, and electron-phonon interactions. A decrease in residual resistivity (109–49 µΩ-cm) and an increase in residual resistivity ratio (1.2–1.39) indicate an enhancement of crystallinity and structural order of CTS films. By first principle study using DFT calculation we have analyzed the effect of atomic site disorder on electronic properties of both bulk and thin film (220) surface form of CTS Heusler alloy. It has been noticed that the ordered bulk structure shows perfect half-metallic nature but for thin film the spin polarization and moment both are deviated from identical value. The spin polarization and magnetic moment both are reduced a lot by introducing atomic site disorder in L2 1 ordered structure. • Co 2 TiSi films with different subtrate temperatures are grown by electron beam evaporator. • Studies the impact of growth substrate temperatures on structural and magnetic properties Co 2 TiSi film. • Resistivity study suggests the presence of different scattering phenomena. • Effect of atomic site disorder on magnetic moment and spin polarization of bulk and thin film by DFT calculations. [ABSTRACT FROM AUTHOR]

We report a systematic experimental and theoretical study of half-metallic Heusler alloys Mn 2 V 1−x Co x Al (x = 0, 0.25, 0.5, 0.75, 1). In this study, using the arc-melting method and optimizing annealing temperatures, we succeed to synthesize Mn 2 V 1−x Co x Al (x = 0, 0.25, 0.5, 0.75, 1) alloys with evident L2 1 (or XA) order. A near compensated ferrimagnetic moment of 0.02 μB/f.u. at 5 K is observed with the Co concentration of 0.5 which is consistent with the S-P rule. In addition, we systematacially investigate the effects of Co concentration on electronic structure of Heusler alloys Mn 2 V 1−x Co x Al (x = 0, 0.25, 0.5, 0.75, 1) using first-principles calculations, and found that the half-metallic characteristic persists for all Co concentrations. In line with our experimental results, employing appropriate atomic site occupation, we obtained a full compensated ferrimagnetic moment of 0 μB/f.u. for stoichiometric Mn 2 V 0.5 Co 0.5 Al alloy. In addition, the robustness of half-metallic properties for compensated ferrimagnet Mn 2 V 0.5 Co 0.5 Al with the variation of atomic disorder are investigated and the results indicate that the Mn-Al swapping weakly destroys the half-metallic properties and the compensated ferrimagnet Mn 2 V 0.5 Co 0.5 Al alloy maintains the high spin polarization under the effect of B2 disorder. • Mn 2 V 1−x Co x Al (x = 0, 0.25, 0.5, 0.75, 1) alloys with evident L2 1 (or XA) order are fabricated successfully. • Magnetic properties can be regulated by component ratio of Co and V. • A full compensated ferrimagnetic moment of 0 μB/f.u. for stoichiometric Mn 2 V 0.5 Co 0.5 Al alloy is obtained. • Half-metallic properties of Mn 2 V 0.5 Co 0.5 Al is robust against atomic disorder. [ABSTRACT FROM AUTHOR]

For the purposes of fitting the characteristics of the Magnesium sulfide (MgS) and, Magnesium selenide (MgSe) semiconductors in Spintronic applications, a theoretical ab-initio investigation of Transition metals (TM=Ti, V, Cr, Mn, Co, Ni) substitution is performed. The equilibrium properties have been studied in the zinc-blende phase of MgS and MgSe. The effects of temperature and pressure on the structural, electronic, thermodynamic, and magnetic properties of our systems are explored as well. It is found that the introduction of the TMs in MgS and MgSe brings out a half-metallic ferromagnetic behavior with 100% polarization around Fermi level in Ti, V, Cr, Co and Ni cases, contrary to the Mn case where the half-metallic feature does not appear. The double exchange mechanism was the mechanism responsible for magnetism in these systems. Finally, the high Curie Temperate (T c) of the ferromagnetic systems reveals that Ti, Cr and V substitutions could play a significant role in spintronic applications. • Electronics & magnetism merge, yielding Innovative materials & components for Spintronics. • Half-metallic magnets are 100% spin polarization; ideal for Spintronic apps. • Investigating transition metal substitutions (Ti, V, Cr, Mn, Co, Ni) in MgS and MgSe. • Half-metallic ferromagnetic found for Ti, V, Cr, Co, & Ni substitutions, except Mn. • High Curie temperature for Cr, V, and Ti substitutions above room temperature. [ABSTRACT FROM AUTHOR]

The rare earth elements are extensively incorporated in combination with alloys to fill up the demanding gaps of applications in future technologies like thermoelectrics. We give detailed prediction of electronic, magnetic, mechanical, thermoelectric, thermodynamic and optical properties of YCoTiX (X = Al, Ga, Si, Ge) quaternary Heusler alloys. The ground state properties reveal the alloys possess the LiMgPdSn-type structure with F -43 m space group. The spin polarized band structure give us a half-metallic nature at optimized lattice parameters. The minority spin band gaps are found to be indirect with calculated values as 0.53 eV for YCoTiAl, 0.61 eV for YCoTiGa, 0.71 eV and 0.62 eV for YCoTiSi and YCoTiGe, respectively. The total magnetic moment follow the Slater-Pauling curve rule of (M = Z tot – 18). Similarly, the optical properties of these alloys depict the similar behavior of electronic states near the Fermi level with substantially spins oriented along the direction of magnetization in all the alloys. The thermoelectric coefficients are investigated to infer their stand for waste heat recovery systems, where Seebeck coefficients detail their n -type behavior. Conversion efficiency is established using the dimensionless figure of merit, zT calculated as 0.75 at 550 K for YCoTiAl, 0.14 at 750 K for YCoTiGa and 0.31 at 750 K for both YCoTiSi (Ge). Thermodynamic parameters convey that all the alloys possess no anomalies with respect to phase transition or instabilities. • Predicted Heusler alloys are new class of functional materials with perfect half-metallicity. • They present robustness with respect to variation of lattice constant. • They have well established thermoelectric response over high temperature range. • They present good opto-electronic response with far-ultraviolet photo detector applications. • Anisotropic in nature, possibility of micro cracks at growing process. [ABSTRACT FROM AUTHOR]

In this study, the half-metallic behavior and magnetic properties of various (001) surfaces for Y 2 CrSn Heusler alloy were investigated using the spin-polarized first-principles method. The spin polarizations of the standard stable YSn-terminated and artificial stable SnSn-terminated (001) surfaces were −96.9% and −95.8%, respectively, using the generalized gradient approximation (GGA) method (−69.2% and −83.0% using the GGA + U method), and thus the two surfaces have potential use in spintronic devices. The spin polarizations of the standard YCr-terminated, artificial YY-terminated, and artificial CrCr-terminated (001) surfaces were only −43.0%, 29.3%, and −40.8%, respectively, using the GGA method (−63.2%, −67.9%, and −44.4% using the GGA + U method). The atomic magnetic moments (AMMs) of the Y and Cr atoms in the outmost layer changed greatly due to the surface states, but little change was found in the AMMs of atoms near the central layer. The average AMMs obtained for the Sn, Y, and Cr atoms using the GGA + U method were only slightly larger than the corresponding AMMs determined using the GGA method. Image 1 • Spin polarizations of stable YSn and SnSn-term (001) surfaces were high. • Spin polarizations of unstable YCr, YY, and CrCr-term (001) surfaces were low. • Atomic magnetic moments of Y and Cr atoms changed little in the outermost layer. • Little change in atomic magnetic moments of atoms near the central layer. [ABSTRACT FROM AUTHOR]

• Origin of the large saturate moment at 5 K in Fe 2 MnGe DO 19 phase was determined. • Phase stability of cubic and hexagonal Fe 2 MnGe was investigated. • "Why Fe 2 MnGe DO 19 phase is stable at room temperature" was discussed. • Information on electronic structure of Fe 2 MnGe DO 19 phase was presented. The electronic structure, phase stability and magnetic properties of cubic and hexagonal type Fe 2 MnGe were investigated and compared with the well-known Heusler alloy Fe 2 MnSi. Three different structures L2 1 , DO 3 and DO 19 were considered for them. In both alloys the cubic phase (L2 1 and DO 3) has a lower total energy comparing with the hexagonal DO 19 phase at 0 K. But in Fe 2 MnGe the energy difference between the DO 19 and L2 1 phases is much smaller than Fe 2 MnSi. The DO 3 disorder can lower the stability of the cubic phase further and make the total energies of hexagonal and cubic phases closer, this can help the DO 19 phase gain stability. Finally, in Fe 2 MnGe, the energy difference is 0.12 eV/f.u., much smaller than the 0.41 eV/f.u. in Fe 2 MnSi. That is the possible reason why Fe 2 MnGe DO 19 phase can be synthesized experimentally and Fe 2 MnSi cannot. L2 1 type Fe 2 MnGe is a half-metal with 100% spin polarization and has a total spin moment of 3μ B /f.u. The spin polarization ratio of DO 3 phase is also high. But for the DO 19 hexagonal phase, a normal ferromagnetic metal character is observed. The calculated total moment for DO 19 type Fe 2 MnGe is larger than 6μ B /f.u. This total moment comes mainly from the large and parallel coupled partial spin moments of Fe and Mn. [ABSTRACT FROM AUTHOR]

• The magnetic moment of Co-V-Ga alloy can be enhanced by Sb substitute for Ga. • Both Co 2 VGa and Co 2 VGa 0.75 Sb 0.25 alloys exhibit a half-metallic band structure. • Excess substitution of Sb for Ga in Co 2 VGa 1− x Sb x compounds can induce martensitic transformation. • Coexistence of both half-metallic and martensitic transition was obtained in Co 2 VGa 1− x Sb x system alloys. Herein, we have investigated, theoretically and experimentally, the influence of Sb-doping, at Ga-site, on crystal structure, martensitic transition (MT) and half-metallicity of Co 2 VGa 1− x Sb x (x = 0, 0.25 and 0.5) Heusler alloys. The results reveal that the Co-V-Ga-Sb alloys with x = 0 and 0.25 exhibit typical half-metallicity, and at x = 0.25 the density of states (DOS) show a wider band gap near the Fermi level in minority states, which implies that Co 2 VGa 0.75 Sb 0.25 is an efficient material with 100% spin polarization. Moreover, Co 2 VGa 0.5 Sb 0.5 exhibits a martensitic transformation from parent phase with L2 1 -type cubic structure to the D0 22 -type tetragonal structure at ∼347 K. In addition, the DOS of Co 2 VGa 0.5 Sb 0.5 also exhibit half-metallicity after expanding the lattice parameter by 2%. The unique features of Co 2 VGa 1− x Sb x Heusler alloys imply that these alloys are promising for high-efficiency spintronics and shape memory devices. [ABSTRACT FROM AUTHOR]

The half-metallic (HM), magnetic, and optical properties of the (001) surface of Ge doped half-Heusler alloys Mn 2 Ge x As 1-x (x = 0.00, 0.25, 0.50, 0.75, and 1.00) are predicted by first-principles method. Among the ten different kinds of Mn 2 Ge x As 1-x (x = 0.00, 0.25, 0.50, 0.75, and 1.00) (001) surfaces, the HM character is only observed in the MnMn-term of Mn 2 Ge (001) surface which represents the priority for optical property in the red visible light region, and the MnAs-term of Mn 2 As (001) surface represents a very high spin polarization P of −97.5% using generalized gradient approximation (GGA) method (−98.4% using GGA + U method), which represents the priority for optical property in the blue visible light region. The spin polarizations of the rest eight kinds of surfaces are very low, thus these surfaces can't be used in spintronic devices. In the energy range of 3.1–15.0 eV for the ultraviolet light, the light absorption capacity of the HM MnMn-term of the Heusler alloy Mn 2 Ge (001) surface is better than that of the nearly HM MnAs-term of the Heusler alloy Mn 2 As (001) surface. Unlabelled Image • Half-metallic character is only observed in the MnMn-term of Mn 2 Ge (001) surface. • MnAs-term of Mn 2 As (001) surface represents high spin polarization P of −97.5%. • MnAs(MnMn)-term represents priority in blue(red) light regions. • MnMn-term is better than MnAs-term in absorption capacity for ultraviolet light. [ABSTRACT FROM AUTHOR]

Highlights • Finite-temperature electron transport is studied by ab initio alloy analogy model. • Phonons, magnons and chemical disorder are treated in a unified way. • Calculations reproduce successfully the measured electrical resistivity. • At temperature 600 K, spin polarization of the current as high as 80% is predicted. • At the Curie temperature 730 K, the Matthiessen's rule is violated by 16%. Abstract We investigate theoretically the combined effect of phonons and magnons caused by finite temperatures on the electrical resistivity of nonstoichiometric half-Heusler NiMnSb alloy. The coherent potential approximation within the alloy analogy model is employed for an efficient treatment of chemical impurities, atomic displacements, and magnetic disorder. Spin fluctuations of local Mn moments are described by two models: (i) uncompensated disordered local moment approach and (ii) tilting of the moments. The calculated resistivity agrees with experimental data, the agreement is good up to 600 K. We show that a strong magnetic disorder leads to a violation of the Matthiessen's rule for the resistivity. We also discuss the spin polarization of the electrical current which exceeds 90% at room temperature but it is dramatically reduced by the magnetic disorder for higher temperatures approaching the Curie point ( T C = 730 K). [ABSTRACT FROM AUTHOR]

Abstract The structural, electronic, and magnetic properties in (001) and (110) surfaces of quaternary Heusler alloy TiZrCoAl were investigated by spin-polarized first-principles calculations by using the Vienna ab-initio simulation package (VASP) based on density function theory. The bulk TiZrCoAl quaternary Heusler alloy was half-metallic (HM) not only using generalized gradient approximation (GGA) method but also using Heyd-Scuseria-Ernzerhof hybrid functional (HSE06) method. For bulk TiZrCoAl alloy, there was an indirect spin-down band gap of 1.095 eV using the GGA method but there was a direct spin-down band gap of 0.460 eV at Γ point using the HSE06 method. The HM feature was ruined in all the surfaces. The spin polarizations P were 91.6%, 97.9%, and 96.1% for TiCo termination of (001) surface, ZrAl termination of (001) surface, and TiZrCoAl termination of (110) surface, respectively, which indicated they were near HM, hence the TiZrCoAl quaternary Heusler alloy was ideal material which could be used for spintronic devices. The total magnetic moment of bulk quaternary Heusler alloy TiZrCoAl was 2.000 μ B per formula unit which satisfied the Slater-Pauling rule. Graphical abstract Image 103 Highlights • The bulk TiZrCoAl quaternary Heusler alloy was HM using both GGA and HSE06 methods. • There was indirect/direct spin-down band gap using GGA/HSE06 method for bulk alloy. • The spin polarizations (91.6%, 97.9%, 96.1%) were high for near HM TiZrCoAl surfaces. • The total magnetic moment of bulk TiZrCoAl alloy was 2.000 μ B /f.u. [ABSTRACT FROM AUTHOR]

Abstract This paper reports results on the structural stability, mechanical, electronic and magnetic behaviour of quaternary ScNiCrX (X = Al, Ga) Heusler alloys under pressure. First principles approach is applied to calculate the structural, mechanical, electronic and magnetic properties of ScNiCrX alloys under pressure. In ferromagnetic phase, both alloys (in Type-γ configuration) are stable. Over a wide pressure range, the calculations of cubic elastic constants (C ij) for both alloys fulfill the necessary criteria for structural stability. Under pressure up to 6.0 GPa, the ScNiCrAl alloy shows half-metallic ferromagnetic behaviour. The ScNiCrGa alloy exhibits half-metallic behaviour over a wide range of pressure (up to 16.0 GPa) as compared to ScNiCrAl alloy. For ScNiCrAl alloy, the spin ↓ energy band gap (E g) increases (0.27–0.43 eV) with increase in pressure (0.0–6.0 GPa) while for ScNiCrGa alloy E g increases from 0.30 to 0.58 eV with increase in pressure from 0.0 to 16.0 GPa. For pressure up to 10.0 GPa, the calculated total magnetic moment, M T (for both alloys) exhibit Slater-Pauling rule, M T = (N V – 18) μ B. Up to 6.0 GPa, it is expected for ScNiCrAl alloy to show 100% spin-polarization (at Fermi-level, E F) while for ScNiCrGa alloy, 100% spin-polarization is possible to achieve for pressure up to 16.0 GPa. On the basis of results, it is suggested that the ScNiCrX Heusler alloys could be suitable candidates for spintronic devices to operate under harsh environment. Graphical abstract Image Highlights • Quaternary Heusler alloys ScNiCrX (X = Al, Ga) are studied under pressure. • Alloys (in Type-γ configuration) are stable in ferromagnetic phase. • ScNiCrAl alloy shows half-metallic ferromagnetic behaviour for pressure ≤6.0 GPa. • ScNiCrGa alloy exhibit half-metallicity for pressure ≤16.0 GPa. • Up to 10.0 GPa, the total magnetic moment, M T follows the Slater-Pauling rule. [ABSTRACT FROM AUTHOR]

Abstract The inverse Heusler alloy Zr 2 RhAl is investigated using first-principles calculations. The calculations are carried out using the full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method that is employed in the WIEN2k package. The structural, electronic, magnetic, and thermoelectric properties are studied. It is found that the ferromagnetic phase of Zr 2 RhAl is the most stable with lattice parameter 6.6328 Å. The calculations showed that there is an energy gap in the spin down channel whereas the spin up channel is metallic, resulting in a 100 % spin polarization at Fermi level. This is an obvious characteristic of half-metallic materials. The calculated total magnetic moment of Zr 2 RhAl is found to be 2 μ B which follows the generalized Slater-Pauling rule. The Curie temperature is estimated to be 607 K using the mean field approximation. Transport properties are studied using the Boltzmann theory with constant relaxation time approximation. The variation of transport properties with temperature is investigated using the two current model. Highlights • The ferromagnetic phase of Zr 2 RhAl is the most stable magnetic phase. • The Zr 2 RhAl have metallic behavior for spin–up channel and a semiconducting behavior for the spin down channel with band gap 0.50635 eV. • The Curie temperature of Zr 2 RhAl was found to be 607 K within the mean field approximation. • The transport properties for the spin-down channel show promising future for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The full Heusler alloy (Fe 2 CoSn) nanowires are formed using AC electrodeposition in AAO templates. • The SEM images have confirmed the average diameter and length of nanowires 40–60 nm and 15 μm respectively. • The M-H loops show the variation of coercivity and saturation magnetization with respect to deposition potential. • The half-metallicity, band gap and 100% spin polarization was also confirmed using density functional theory (DFT). Abstract Fe 2 CoSn Heusler alloy nanowires (NWs) were synthesized for the first time through alternating current (A.C) electrodeposition due to its manufacturing and size tailoring ease. To approach our desired goal, deposition potential was used to control the alloy composition of Fe, Co and Sn contents as it was almost inversely proportional to the composition ratio of Sn and (Fe, Co). The effects of deposition potential on morphology, chemical composition, crystal structure and electric/magnetic properties were investigated. According to the scanning electron microscopy (SEM) micrographs, the Fe 2 CoSn NWs exhibited diameter of about 40–60 nm range and the length existing in the range of 15 µm. X-ray diffraction (XRD) patterns reveal that two types of reflection were observed i.e. fundamental (A2-type crystal structure) and super-lattice (L2 1 crystal structure) reflection. Almost 35 nm was the average grain size calculated through XRD technique using full width half maximum (FWHM). The composition of Fe 2 CoSn nanowires has been confirmed by using EDX analysis, whereas surface chemistry of Heusler alloy (Fe 2 CoSn) NWs was examined through FTIR. Magnetic measurement indicated that Fe 2 CoSn Heusler alloy was ferromagnetic at room temperature with a maximum coercivity of 484 Oe at 17 V. Two probe (I-V) curve showed non-ohmic character and Hall measurement (Four probe) revealed the inverse relation between resistivity (ρ), mobility (µ) and followed excellent transport as well as spin dependent properties of Heusler alloy (Fe 2 CoSn) NWs. Half metallicity in (Fe 2 CoSn) Heusler alloy NWs was confirmed by full potential lineralized augmented plane wave methods (FP-LAPW) within density functional theory (DFT) in detail. These results revealed that Heusler alloy (Fe 2 CoSn) NWs have wide range of multifunctional properties such as combination of magnetism and exceptional transport properties in spintronic devices. [ABSTRACT FROM AUTHOR]

• We performed a computational and theoretical study of FeCrTiAl. • Our calculations indicate that this material undergoes several band structure transitions. • Another interesting feature of FeCrTiAl is that its spin polarization changes sign from negative to positive under pressure. • At the largest considered lattice parameters, this compound exhibits nearly 100% spin polarization. Spin-gapless semiconductors (SGS) represent a new type of compounds with potential applications in novel spintronic devices. Here, we performed a comprehensive computational and theoretical study of FeCrTiAl, a quaternary Heusler compound that was recently predicted to exhibit nearly SGS properties. Our calculations indicate that this material undergoes several band structure transitions from essentially semimetallic phase at smaller lattice constants to nearly type-II SGS at the ground state, then to nearly type-III SGS and further to nearly type-I SGS, as the lattice parameter is increased. Another interesting feature of FeCrTiAl is that its spin polarization changes sign from negative to positive as the volume of the cell increases. At the largest considered lattice parameters, this compound exhibits nearly 100% spin polarization. The mechanical expansion discussed in this text may be achieved, in principle, either by applying an epitaxial strain in thin-film geometry, or by chemical substitution, for example with non-magnetic element of larger atomic radius. We hope that the presented results may provide guidance for further research on mechanical strain induced manipulation of electronic and magnetic properties of spin-gapless semiconductors. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) studies are made to calculate the electronic, magnetic, and transport characteristics of potassium lanthanide KXO2 (X = Pr, Nd, and Pm) oxides have been studied by using the WIEN2K code. Perdew Burke Ernzerhof-Generalized Gradient approximation (PBE-GGA) is used for the exchange-correlation energy of the crystal structures in the hexagonal phase. However, the volume-optimized graphs depict that these compounds are energetically stable in the ferromagnetic state. Moreover, the studies of the spin-up channels of the band structure and density of states (DOS) reveal their metallic behavior whereas semiconductor nature has been noticed through spin-channels. Therefore, studied materials have half metallicity nature with 100% spin polarization at the Fermi level (EF). Total and partial magnetic moments of KXO2 (X = Pr, Nd, and Pm) and individual atoms exist due to unpaired 4f electronic states of the lanthanide ions, present at the EF. The energy difference between anti-ferromagnetism and ferromagnetism versus the volume optimization curve gives the curie temperature (Tc). The volume optimization curves show a flat region where both magnetic states have similar energies. This means the material can exist at the equilibrium volume in either state. Finally, thermoelectric properties are calculated by the BoltzTraP code. Our results unveil that these potassium-based lanthanide oxides are potential materials for devising spintronics devices and lifting future practical applications. • Studied materials have half metallicity nature with 100% spin polarization at E F. • Total and partial magnetic moments of KXO 2 and individual atoms exist due to unpaired 4 f states of La. • Energy difference between anti-ferromagnetism and ferromagnetism energy vs volume optimization curve gives value of T C. • The figure of merit is higher for KPmO2, KNdO2 as compared to KPrO2. [ABSTRACT FROM AUTHOR]

The investigation of magnetic domain wall resistance (DWR) in epitaxial Co 2 MnAl (CMA) thin films, a Heusler alloy, has revealed a remarkable phenomenon of sign change. This intriguing behavior is attributed to the half-metallic band structure with high spin polarization, as verified by negative anisotropic magnetoresistance in the two-current model. In this way, the scattering relaxation time for the majority and minority electrons, which is primarily determined by the density of states of majority and minority electrons, undergoes a dramatic change in the vicinity of the half-metallic band gap. This results in an unusual upturned relaxation time ratio, leading to the sign change of intrinsic DWR. These findings deepen our understanding of the intricate dynamics of spin-dependent phenomena in half metals and shed light on the entangled magnetoresistance in Heusler alloy with high spin polarization. • Successful demonstration of sign change in magnetic domain wall resistance (DWR) in Co 2 MnAl (CMA) thin films. • Negative anisotropic magnetoresistance proves the high spin-polarization of CMA in the two-current model. • Unique half-metallic band structure and high spin polarization of CMA attributed to sign change in DWR. • Dramatic change in relaxation time ratio near half-metallic band gap leads to intrinsic DWR sign change. [ABSTRACT FROM AUTHOR]

On the basis of first principles calculations, the electronic structures and magnetic properties of quaternary Heusler alloys RbCaNZ (Z = O, S, and Se) were studied. The negative formation energies indicated that all these compounds were thermodynamically stable and thus may be experimentally synthesized at appropriate conditions in the future. The results showed that Y I structure was the most favorable configuration among the three possible structures. All compounds were found to be half-metallic ferromagnets. The characteristic of energy bands and origin of half-metallicity were also verified. The total magnetic moments of RbCaNZ (Z = O, S, and Se) compounds were obtained 2 μ B per formula unit, which were in an agreement with Slater-Pauling rule ( M tot = 12  −  Z tot ). Half-metallicity was preserved at ranges of 5.06–8.36 Å, 5.96–8.81 Å, and 6.13–8.73 Å for RbCaNO, RbCaNS, and RbCaNSe compounds, respectively, which show that these quaternary Heusler compounds may be potential candidates in spintronic applications. [ABSTRACT FROM AUTHOR]

We investigated temperature dependence of differential conductance G ( V ) in planar junctions consisting of Co-based Heusler alloy Co 2 TiSn and superconductor Pb. Ferromagnetic Co 2 TiSn was predicted to be half-metal by first-principles band calculations. The spin polarization P of Co 2 TiSn was deduced to be 60.0 % at 1.4 K by the Andreev reflection spectroscopy. The G ( V ) spectral shape was smeared gradually with increasing temperature and its structure was disappeared above the superconducting transition temperature T c . Theoretical model analysis revealed that the superconducting energy gap Δ was 1.06 meV at 1.4 K and the T c was 6.8 K , indicating that both values were suppressed from bulk values. However, the temperature dependent Δ ( T ) behavior was in good agreement with that of the Bardeen-Cooper-Schrieffer (BCS) theory. The experimental results exhibit that the superconductivity of Pb attached to half-metallic Co 2 TiSn was kept the conventional BCS mechanism characterized strong-coupling superconductors while its superconductivity was slightly suppressed by the superconducting proximity effect at the Co 2 TiSn/Pb interface. [ABSTRACT FROM AUTHOR]

The ground state properties along with thermodynamic and thermoelectric properties of quaternary CoFeCrAs alloy within the ordered LiMgPdSn-type structure have been investigated by employing first-principles calculations. The alloy offers half-metallic ferromagnet character with an indirect band gap of 1.12 eV in the minority spin state with total spin magnetic moment of 4µ B and follows Slater-Pauling relation. Effects on various properties of the material has been studied by the variation of the pressure and temperature. CoFeCrAs tenders large value of the Grüneisen parameter and small value for the thermal expansion coefficient. The materials present high Seebeck coefficient and huge power factor with the room temperature value of ∼−40 μV/K and 18 (10 14   μ Wcm −1  K −2  s −1 ) respectively, which make CoFeCrAs promising candidate for efficient thermoelectric material. [ABSTRACT FROM AUTHOR]

We studied the origin of the enhancement of current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) effect by inserting a thin amorphous CoFeBTa (CFBT) underlayer below a Co 2 (Mn 0.6 Fe 0.4 )Ge (CMFG) Heusler alloy ferromagnetic (FM) layer. Large magnetoresistance ratio of ∼25% and resistance change-area product of ∼7.5 mΩ μm 2 were obtained at room temperature by inserting a CFBT (1.2 nm) underlayer. X-ray diffraction (XRD) and transmission electron microscope analyses confirmed that the CMFG FM layer deposited on the CFBT underlayer was amorphous in the as-deposited state and crystallized to a B2-ordered polycrystalline film by annealing at 300 °C. The degree of B2 order ( S B2 ) of the CMFG films was estimated by anomalous XRD using x-ray energies around the Co K- absorption edge. S B2 of the CMFG film deposited on the amorphous CFBT (1.2 nm) underlayer was ∼0.76, much larger than that of the CMFG film deposited on a crystalline CoFe underlayer ( S B2 ∼0.47). First-principles calculations indicated that the spin polarization of the sp -conduction electrons in CMFG increases with increasing S B2 , which accounts for the enhanced CPP-GMR effect in the pseudo spin-valve by inserting an amorphous CFBT underlayer. [ABSTRACT FROM AUTHOR]

The electronic and magnetic properties of novel Heusler alloys Co 2 HfZ (Z = Al, Ga, Ge, Sn) with Hg 2 CuTi- and Cu 2 MnAl-type structures are investigated by first-principles calculations. It is found that the Cu 2 MnAl-type structure is more stable than the Hg 2 CuTi-type structure for all the Co 2 HfZ alloys. The Hg 2 CuTi-type structures of Co 2 HfZ show a metallic ferrimagnetic character with a high spin polarization. The Cu 2 MnAl-type structures have half-metallic ferrimagnetic behavior with minority-spin gaps of 0.38, 0.06, 0.55 and 0.46 eV for Co 2 HfAl, Co 2 HfGa, Co 2 HfGe and Co 2 HfSn, respectively. The total magnetic moments of the Cu 2 MnAl-type alloys are 1µ B , 1µ B , 2µ B and 2µ B , which obey the Slater–Pauling rule (M tot = Z tot − 24). Analysis of the projected density of states indicates clear gaps resulting from the hybridization of Co (A) and Co (B) atoms. The half-metallicity makes Co 2 HfZ with Cu 2 MnAl-type structure promising candidates for spintronic applications. [ABSTRACT FROM AUTHOR]

First-principles calculations, were carried out to study the structural stability of the cubic [ (F m 3 ‾ m) , (F 4 ‾ 3 m) ] and tetragonal [ (I 4 / m m m) , (I 4 ‾ m 2) ] phases, of R u 2 V Z (S i ; G e) full Heusler compounds; where Energy of formation, elastic, Mechanical, phonon and thermodynamic properties and electronic density of states were determined. Through our results, all ferromagnetic phases exhibit a total magnetic moment of 1 μ B for both R u 2 V S i and R u 2 V G e compounds, except the tetragonal (I 4 ‾ m 2) phase that manifest a zero ( 0 μ B) total magnetic moment.Further, the antiferromagnetic state of the cubic phase F m 3 ‾ m R u 2 V Z (S i ; G e) was found energetically more favorable than the ferromagnetic one.The analysis of the calculated elastic and dynamic properties, revealed that only the regular cubic phase (F m 3 ‾ m) of the R u 2 V S i and the regular tetragonal phase (I 4 / m m m) of the R u 2 V G e are the most stable among the considered phases. The calculated electronic density of states for the ferromagnetic stable phases, confirm the existence of a half-metal character with high spin polarization (P n) of: ∼ 91 % and ∼ 100 % for the R u 2 V S i and R u 2 V G e respectively. • In This article applied the Full full-potential linearized augmented-plane-wave method (FP-LAPW) to the determination of the structural, dynamic mechanical and electronic properties of the two full Heusler compounds R u 2 V S i and R u 2 V G e. • The antiferromagnetic state for the cubic (F m 3 ‾ m) R u 2 V Z (S i ; G e) compounds was found more favorable than the ferromagnetic one. • The analysis of the calculated elastic and dynamic properties, show that only the regular cubic phase (F m 3 ‾ m)) of the R u 2 V S i and the regular tetragonal phase (I 4 / m m m) of the R u 2 V G e are the most stable among the considered phases. • The electronic density of states for the ferromagnetic stable phases, confirm the half-metal character with high spin polarization for the R u 2 V S i and R u 2 V G e respectively. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and transport properties of a new quaternary Heusler alloy CoMnVAs have been investigated by employing generalized gradient approximation (GGA), modified Becke-Johnson (mBJ) and GGA with Hubbard U correction (GGA + U). The alloy is energetically more stable in ferromagnetic Y 1 type structure. Elastic parameters reveal high anisotropy and ductile nature of the material. CoMnVAs shows half-metallic ferromagnet character with 100% spin polarization at Fermi level with band gap of 0.55 eV in the minority spin state. The alloy also possesses high electrical conductivity and Seebeck coefficients with 15 μVK −1 at room temperature, achieving a figure of merit of 0.65 at high temperatures. The high degree of ductility, 100% spin polarization and large Seebeck coefficient, makes it an attractive candidate to be used in spin voltage generators and thermoelectric materials. [ABSTRACT FROM AUTHOR]

We report on magnetism, transport and spin polarization characteristics of the melt-spun Cu 2 MnSn alloy prepared by the rapid quenching technique. The as- cast ribbons showed a relatively well ordered chemical composition (Cu = 50.4%, Mn = 27.1%, Sn = 22.5%). The structural characterization by using X-ray diffraction shows L2 1 /B2 crystalline structure with the lattice parameter a = 6.196 Å. The magnetic and transport measurements show a metallic behavior with the Curie temperature of 530 K and reveal anisotropic character with the easy magnetization plane parallel with respect to the ribbon plane. As-cast Cu 2 MnSn ribbons show the spin polarization measured by using Andreev reflection technique within the range 68–75%. [ABSTRACT FROM AUTHOR]

A succinct summary of various physical characteristics of halide double perovskites Cs 2 KXCl 6 : (X = Ti and V) has been summarized using Density Functional Theory (DFT), as applied in WIEN2k simulation code. These material's stability in Fm-3 m cubic symmetry is confirmed by structural optimization, tolerance factor and elastic parameters. The electronic band structures and density of states calculated using GGA and G G A + m B J show that these materials are semiconducting in spin down channels. The crystal field splitting of d-orbitals is used to explain the semiconducting ferromagnetic nature of these Ti- and V- based halide double perovskites. The ferromagnetic character of these double perovskites is suggested by the optimization and asymmetric DOS across Fermi level. We have also discussed about the origins of half-metallic bandgap and magnetism. The total magnetic moments of the Ti and V-based double perovskites are 1 μ B and 2 μ B, respectively, with the transition metal atoms (Ti/V) accounting for the major contributions. At the Fermi level, these double perovskites have 100% spin polarization, indicating that they could be used in spintronics. • The DFT studies confirm the structural stability of double perovskites(DPs) Cs 2 KXCl 6 : X = Ti, V in ferromagnetic state at low temperature. • Structural optimization and tolerance factor confirms the structural stability of the DPs. • The DPs shows half-metallic nature in both GGA and mBJ calculations. The half-metallic character of the DPs is also supported by their integral magnetic moments. • The mechanical parameters shows Cs 2 KVCl 6 as brittle while as Cs 2 KTiCl 6 as ductile. • These DPs exhibit 100% spin polarization at the Fermi level suggests that they might be used in spintronics. • The findings may be beneficial for experimentalists to prepare these type of DPs in laboratories for commercial uses. [ABSTRACT FROM AUTHOR]

• B2-25% and B2-75% disordered structures are most favorable for experimental growth due to their lowest formation energy. • B2-25% and B2-75% disordered structures show metallic to half-metallic transformation, resulting in 100% spin polarization. • All disordered structures keep magnetic moment nearly the same as that of the ordered structure. Co-based Heusler alloys are mostly studied for their half metallicity, resulting in 100% spin polarization and a very high Curie temperature, which are the prerequisites for spintronics devices. As the site (swap) disorder has a significant impact on these properties, understanding of the impact of site disorder on these properties is of great interest for the spintronic community. First principle calculations within density functional theory (DFT) have been carried out on the structural, electronic, and magnetic properties of the B2 disordered Co 2 MnAl full Heusler alloy along with that of L2 1 ordered structure for comparison purpose. The plane wave pseudopotential method, within the Generalized Gradient approximation for exchange correlation functional was used to study B2 disordered Co 2 MnAl Heusler alloy. The degree of site (swap) disorder is systematically varied from 0% to 100% in steps of 12.5% using the supercell approach. DFT calculations reveal no considerable changes in the structural and magnetic properties of Co 2 MnAl by the presence of the disorder and are found to be the same as for the L2 1 structure. However, on the other hand, electronic properties such as, the spin polarization increased from 76% to 100% in the case of B2-25% and B2-75% disorder from the L2 1 structure resulting in half-metallic character. The study further suggests that static-magnetization and structural properties of Co 2 MnAl Heusler alloy are robust against site disorder. [ABSTRACT FROM AUTHOR]

Recent progress in spin caloritronics has boosted exploration of materials for their application in this novel field. Heusler alloys which were being hailed as thermoelectric and magnetic materials have seen uprise for their suitable properties however lack of studies featuring good coupling between magnetic and thermoelectric properties have seen little impact in the field of spin-caloritronics. Present work explored doping of transition metal in a thermoelectric half-Heusler alloys NbCoSb on Nb site to induce spin-polarization and spin-dependent transport properties. Co (Mn) doping results in 98.09% (19.38%) negative spin polarization and 0.51 μ B /f.u. (1.98 μ B /f.u.) magnetic moment. Magnetic exchange parameter shows presence of long range RKKY-type interaction in Co and Mn doped NbCoSb. On one-hand, doping of Co and Mn in NbCoSb suppressed the electronic transport properties whereas, on the other hand spin dependent Seebeck effect is introduced. The synergistic effect of magnetic and thermoelectric properties in non-magnetic NbCoSb via doping of Mn and Co shows large variation in the value of Seebeck coefficient, electrical conductivity and electronic thermal conductivity with flipping of spin-directions suggests Co rich NbCoSb as a promising candidate for spin-caloritronics application. • Well known thermoelectric half-Heusler alloy NbCoSb is studied for spin-caloritronics. • Magnetism is induced in NbCoSb with Co and Mn doping. • High spin polarization and spin dependent Seebeck effect is introduced with Co doping. • Synergistic effect of thermoelectric and magnetic properties are reported. [ABSTRACT FROM AUTHOR]

• The total magnetic moment of all investigated compounds is obtained to be 5 µB. • The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds are mechanically stable. • The ZT of LiCrTe and LiCrSe can be increased to a comparatively high value (ZT = 0.9495 for LiCrSe and ZT = 0.9507 for LiCrTe) by optimizing the carrier concentration to n = 84.6 * 1021 cm−3 for LiCrSe and 67.4 * 1021 cm−3 for LiCrTe, respectively. • These materials could be useful for spintronic application. The electronic, elastic, and thermoelectric behaviors of the half-Heusler LiCrX (X = S, Se, and Te) compounds in the Type I phase are investigated. These three kinds of alloys have minimum energies of type I, rather than types II and III. As a result, Li, Cr, and X (X = S, Se, Te) atoms prefer the positions (0.25, 0.25, 0.25), (0.75, 0.75, 0.75), and (0, 0, 0) respectively. LiCrSe and LiCrTe are true half-metal ferromagnetic compounds with a spin polarization of 100 %, whereas LiCrS is a false half metal alloy. The mBJ-GGA potential technique is also used for calculating electronic, magnetic, and thermoelectric features. The predicted total magnetic moment of LiCrSe and LiCrTe alloys is 5 µ B per formula unit, the majority of which is contributed by Cr. So, LiCrSe and LiCrTe alloys could be suitable for spintronic applications. The elastic properties of LiCrS, LiCrSe, and LiCrTe alloys in Type I phase are analysed and obey to the stability criteria, both LiCrS and LiCrSe are anisotropic, while LiCrTe is isotropic. The classical Boltzmann theory has been employed to investigate thermoelectric performance. The ZT of LiCrTe and LiCrSe can be increased to a comparatively high value (ZT = 0.9495 for LiCrSe and ZT = 0.9507 for LiCrTe) by optimizing the carrier concentration to n = 84.6 * 1021 cm−3 for LiCrSe and 67.4 * 1021 cm−3 for LiCrTe, respectively. In addition, decreasing the chemical potential of LiCrSe by 0.013 Ryd and LiCrTe by 0.025 Ryd, respectively, yields the same results for ZT. The ZT value of LiCrS exhibits a considerable value, and at 1000 K, it can be as high as 0.7091. [ABSTRACT FROM AUTHOR]

The structural stability, electronic structure, mechanical, magnetic and thermal properties of Co and Ni based half-Heusler (HH) alloys are studied. The most stable phase for CoCrSb, NiCrSb, NiCrBi, CoMnSb, CoMnBi and CoCrBi alloys is found to be γ-phase, whereas α-phase is the most stable phase for NiMnBi and NiMnSb among the three different phases (α, β, γ). As the pressure is increased, structural phase transition from γ-phase to α-phase is predicted for NiCrSb, CoCrBi, NiCrBi, CoMnBi, γ-phase to β-phase for CoMnSb and α-phase to β-phase for NiMnSb, at the pressures of 66.96 GPa, 16.91 GPa, 92.50 GPa, 14.58 GPa, 79.23 GPa and 71.47 GPa respectively. Density of states plot shows that there is no energy gap in spin-up state of all these HH alloys and in the spin-down state, the valence and conduction states are separated by a semiconducting energy gap. Thus, these compounds are half metallic. The spin polarized calculations predicted that these Heusler alloys are ferromagnetic nature. The total magnetic moment per unit cell (μ cell) is found to be closer to the integer value of 2 μB, 3 μB and 4 μB. The 100% spin polarization at E F confirms the half-metallic nature of these materials. The dynamical stability of novel HH alloys has also been investigated by computing phonon density of states and it shows that these alloys (except CoCrBi and CoMnBi) are dynamically stable. [ABSTRACT FROM AUTHOR]

A series of full Heusler (FH) alloys Co 2 FeZ (Z = Al, Ga, Si, Ge, S, Se and Te) have been investigated using density functional theory (DFT) with full potential-linearized augmented plane wave (FPLAPW) method within generalized gradient approximation (GGA) and Perdew-Burke-Ernzerhof (PBE) functional. Most stable structures are determined by considering four different atomic arrangements i.e. L2 1 -I/II (conventional) and XA-I/II (inverse) configurations. Stable magnetic phases like anti-ferromagnetic (AFM), nonmagnetic (NM) and ferromagnetic (FM) are evaluated and results revealed that FM phase is the most stable of all alloys. Spin band structures are calculated by applying GGA and GGA + mBJ approach. The results showed the half metallic nature of Co 2 FeAl and Co 2 FeGe alloys. The obtained band diagrams are compared with density of states (DOS) and revealed that the both Fe and Co atoms contributes maximum in total magnetic moment (MM). The calculated values of total magnetic moment (M T) of all compounds range from 4 to 6 μ B and are in well agreement with the findings of Slater-Pauling Rule (SPR). Both alloys i.e. Co 2 FeAl and Co 2 FeGe showed 100% level of spin polarization (SP) at Fermi level. Mean field approximation (MFA) is employed to determine Curie temperature (Tc) and the values thus obtained are higher than room temperature. Furthermore, the thermoelectric parameters i.e. Seebeck coefficient (S) along with thermal (κ) and electrical (σ) conductivities for both Co 2 FeAl and Co 2 FeGe alloys are calculated and discussed in detail. The obtained results envisaged that the investigated alloys are suitable candidates for thermoelectric and spintronic applications. • Structural stability using conventional and inverse atomic arrangements. • Determination of spin band diagrams using GGA and GGA + mBJ. • Half metallic behavior through spin polarization. • Calculations of Curie temperature and magnetic moment. • Study of thermoelectric parameters. [ABSTRACT FROM AUTHOR]

Heusler compounds are a large group of intermetallic compounds with over 1000 members with similar crystal structures having a vast array of tunable properties. These properties depend on the number of valence electrons per formula unit allowing tuning of properties through composition and alloying. The Heusler lattice parameters span many metal oxides and semiconductors and their crystal structures are closely related. For spintronic applications, the magnetic and half-metallic properties, in particular, are of great interest. In this paper the electronic and magnetic properties of Heusler compounds are discussed as well as the importance of composition and defect control on tailoring their properties. Examples of applications include the great success of Heusler magnetic tunnel junction in metallic spintronic devices. The potential of going beyond metallic spintronics to the integration of Heusler compounds with III–V semiconductors for semiconductor spintronics device physics and technology, the tuning of magnetic properties, and the fabrication of Heusler compound heterostructures and superlattices are also discussed. [ABSTRACT FROM AUTHOR]

Bulk (Mn 1- x Co x ) 2 VAl ( x = 0, 0.25, 0.50) alloys in highly ordered L 2 1 structure with a very small amount of B 2 disorder have been prepared and their magnetic properties have been measured. The value of saturation magnetizations of the alloys with x = 0, 0.25 and 0.50 are 1.88 μ B , 0.84 μ B and 0.07 μ B , respectively, being consistent with 2.00 μ B , 1.00 μ B and 0 μ B , respectively, predicted by the Slater–Pauling rule. This indicates that the stoichiometric MnCoVAl alloy is a fully compensated ferrimagnet (FCF). Spin polarization measurements using point contact Andreev reflection technique showed that the quaternary alloys exhibited higher intrinsic spin polarization than the parent ternary composition. The spin polarization of 0.60 deduced for the MnCoVAl alloy suggests that spin-polarized current can be extracted from FCF. Curie temperature ( T C ) and the effective anisotropy constant of (Mn 1- x Co x ) 2 VAl alloys decrease with increase in Co content. [ABSTRACT FROM AUTHOR]

We report enhancement of L2 1 order and the resultant improvement of spin polarization of Co 2 MnSi (CMS) Heusler alloy thin films by a small amount of Ag alloying ( x Ag ⩽ 4.5 atomic (at.) %). The degree of L2 1 order in CMS increases with x Ag (=2.7 at.% and 4.5 at.%), which shows a positive correlation with the magnitude of negative anisotropic magnetoresistance ratio, suggesting the enhancement of spin polarization. Since the benefit of Ag-doping was confirmed even at low annealing temperature around 350 °C, this method could be useful for processing spintronic devices using Heusler alloys at relatively low annealing or substrate temperature. [ABSTRACT FROM AUTHOR]