Search

Magnetic materials with high negative spin polarization have been sought as a building block to increase the design freedom and performance of spintronics devices. In this paper, we investigate negative spin polarization of Mn2VGa Heusler alloy in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices. We fabricated an epitaxial CPP-GMR stack consisting of Mn2VGa/Ag/CoFe with L21 ordering in the Mn2VGa layer and observed negative magnetoresistance (MR), which provided evidence of negative spin polarization. The MR ratio depended on thermal treatments (deposition at an elevated temperature and post-annealing), because these processes affected the ordering, roughness, and magnetic properties of Mn2VGa. The maximum MR ratio reached −1.8% at room temperature and −3.0% at low temperatures, representing the highest among the negative MR values in pseudo-spin-valve CPP-GMR devices despite the underestimation due to an incomplete antiparallel magnetization configuration. These findings demonstrate the potential of Mn2VGa for a material with high negative spin polarization. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the spin transport properties of binuclear manganese phthalocyanine (M n 2 P c 2) spintronic devices sandwiched between two nickel electrodes using the non-equilibrium Green's function method in combination with density functional theory. Based on the calculation results, the M n 2 P c 2 device exhibited excellent spin-filtering capabilities, demonstrating an exceptionally high spin filter efficiency (SFE). Irrespective of the parallel or antiparallel orientation of magnetization in the electrodes, we observed that when both manganese atoms were in a spin-up state, the SFE of spin-resolved currents under finite bias and the thermoelectric currents induced by temperature gradients at fixed temperatures were both close to 100%. The large spin Seebeck polarization of the M n 2 P c 2 device was also obtained at low reference temperatures. This study explores the potential for developing multifunctional spintronic single-molecule devices using Ni − M n 2 P c 2. [ABSTRACT FROM AUTHOR]

We present computational results on electronic, magnetic, and structural properties of CoVMnSb, a quaternary Heusler alloy. Our calculations indicate that this material may crystallize in two energetically close structural phases: inverted and regular cubic. The inverted cubic phase is the ground state, with ferrimagnetic alignment, and around 80% spin polarization. Despite having a relatively large bandgap in the minority-spin channel close to the Fermi level, this phase does not undergo a half-metallic transition under pressure. This is explained by the "pinning" of the Fermi level at the minority-spin states at the Γ point. At the same time, the regular cubic phase is half-metallic and retains its perfect spin polarization under a wide range of mechanical strain. Transition to a regular cubic phase may be attained by applying uniform pressure (but not biaxial strain). In practice, this pressure may be realized by an atomic substitution of non-magnetic atoms (Sb) with another non-magnetic atom (Si) of a smaller radius. Our calculations indicate that 25% substitution of Sb with Si results in a half-metallic regular cubic phase being the ground state. In addition, CoVMnSb0.5Si0.5 retains its half-metallic properties under a considerable range of mechanical pressure, as well as exhibits thermodynamic stability, thus making this alloy attractive for potential spintronic applications. We hope that the presented results will stimulate experimental efforts to synthesize this compound. [ABSTRACT FROM AUTHOR]

Exploring the spin transport characteristics of magnetic tunnel junctions based on half-metallic Heusler holds significance, not only in unraveling the fundamental physics at play but also in advancing applications of spintronic devices. Here, density functional theory in conjunction with non-equilibrium Green's functions has been systematically employed to investigate two prominent Heusler alloys, Co2CrAl and CoFeCrAl, which are of direct interest to the candidates of magnetic tunnel junction. The electronic structures of two Hesler alloys reveal that both exhibit characteristics of half-metallic ferromagnets, featuring a substantial spin-down bandgap and achieving 100% spin polarization. The tunneling magnetoresistance ratios obtained for Co2CrAl/AlP/Co2CrAl and CoFeCrAl/AlP/CoFeCrAl magnetic tunnel junctions are determined to be 173% and 59%, respectively, with the former exhibiting superior device characteristics. Therefore, the Co2CrAl/AlP-based magnetic tunnel junction demonstrates ideal performance, providing new opportunities for two-dimensional spintronics. [ABSTRACT FROM AUTHOR]

This study investigates the structural, mechanical, electronic, magnetic, and thermoelectric properties of ZrMnX (X = As, Sb, Te) half Heusler alloys using spin‐polarized density functional theory (SPDFT) with WIEN2K code using full potential linearized augmented plane wave(FP‐ LAPW) technique. Results indicate the ferromagnetic phase's stability over the non‐magnetic phase in all three alloys. Band structures and density of states highlight the half‐metallic nature of ZrMnX. These alloys exhibit mechanical stability, ductility, and directional properties. Magnetic moments align with the Slater–Pauling rule. Thermoelectric properties, including Seebeck coefficient, electrical and thermal conductivity, and thermoelectric figure of merit, are evaluated using semi‐classical Boltzmann theory. The Seebeck coefficient values for ZrMnX (X = As, Sb, Te) are 144.7, 123.3, and −182.6 µV K−1, respectively at 1200 K with corresponding highest figure of merit 1.0, 0.7, and 1.78. These findings suggest the suitability of these alloys for spintronic devices and high‐temperature thermoelectric applications due to their observed spin‐polarized character and high figure of merit. [ABSTRACT FROM AUTHOR]

High spin-injection-efficiency (SIE) and thermal spin-filter-effect (SFE) from a magnetic material to a barrier material are crucial to the high performance of a spintronic device and a spin caloritronic device, respectively. By performing a nonequilibrium Green's function combined with first-principles calculations, we study the voltage-driven and temperature-driven spin transport properties of a half Heusler alloy RuCrAs based spin valve with different atom-terminated interfaces. The spin valve with a CrAs-top (or Ru-top) interface structure has an ultrahigh equilibrium magnetoresistance (MR) ratio of ∼1.56 × 109% (or ∼5.14 × 108%), ∼100% SIE, a large MR ratio, and high spin current intensity under bias voltage, suggesting that it has a great potential application in spintronic devices. The spin valve with the CrAs-top (or CrAs-bri) interface structure has a perfect SFE due to its very high spin polarization of temperature-driven currents, and it is useful in spin caloritronic devices. [ABSTRACT FROM AUTHOR]

In this study, we present results of a comprehensive computational and experimental study of CoFeVAl and CoFeV0.5Mn0.5Al Heusler alloys. It is shown that while CoFeVAl exhibits a fairly large degree of spin polarization, this material is not half-metallic due to the presence of the vanadium spin-down states at the Fermi level. However, replacing 50% of vanadium with manganese results in a nearly half-metallic transition, largely due to the shift of the Fermi level towards occupied states. Moreover, the half-metallicity of CoFeV0.5Mn0.5Al is rather robust in a wide range of considered mechanical strain and under experimentally observed B2-type atomic disorder, thus making this alloy potentially suitable for practical spintronic applications. Both considered alloys exhibit ferromagnetic alignment at larger lattice constants, aside from a relatively small magnetic moment of vanadium which is anti-aligned with the magnetic moments of Co, Fe and Mn. We have synthesized both CoFeVAl and CoFeV0.5Mn0.5Al alloys in cubic structure with some structural disorder using arc melting and annealing. The structural and magnetic properties of the synthesized CoFeV0.5Mn0.5Al alloy are in good agreement with the theoretical calculations but vary slightly from the parent compound. [ABSTRACT FROM AUTHOR]

This research paper explores the structural, electronic, magnetic, elastic, dynamic, and thermoelectric properties of sp-based half-Heusler (HH) RbBaX (X = Si and Ge) compounds using density functional theory (DFT) and the full-potential linearized augmented plane wave (FP-LAPW) method within the WIEN2k software package. We evaluate the exchange correlation potential using two different approaches: The generalized gradient approximation (GGA) and the modified Becke–Johnson approach. We observe that RbBaX (X = Si and Ge) adopts a ferromagnetic configuration based on the analysis of total energy against volume. We establish that these alloys possess a genuine half-metallic character because of the full spin polarization observed at the Fermi level in their electronic spectrum. Both compounds under investigation have a total magnetic moment of 1.00 μ B, in agreement with the Slater–Pauling principle. The Born stability criteria for cubic structures and phonon dispersion patterns confirm the mechanical and dynamic stability of RbBaX (X = Si and Ge) alloys. The thermoelectric properties reveal a p-type semiconductor nature, characterized by significant positive Seebeck values. The thermoelectric figure of merit (ZT) calculated for both alloys at 300 K approaches unity, highlighting their remarkable thermoelectric efficiency. [ABSTRACT FROM AUTHOR]

Generally, Co-based Heusler alloys are the center of interest because of their properties such as high Curie temperature, spin polarization, and high value of exchange bias. Herein, we have used the macroscopic technique to probe the low-temperature exotic properties of M1.5Co0.5FeAl. First, we have analyzed the dc magnetization data, and it unfolds the presence of a glassy phase at 33 K. The cluster spin glass phase is authenticated by measuring ac susceptibility. Furthermore, using empirical models like power law and Vogel–Fulcher fitting, the relaxation time for the spin is of the order of τ ∼ 10−9 s, confirming the presence of a cluster spin glass in Mn1.5Co0.5FeAl below an irreversible temperature. The H–T phase space diagram ensures that it follows the Ising spin model. Furthermore, the glassy phase of the system is confirmed by magnetic relaxation, memory effect, and the presence of an exchange bias instead of a minor loop below spin-freezing temperature (Tf ∼ 33 K). [ABSTRACT FROM AUTHOR]

We investigate the effects of off-stoichiometric compositional variations from the Co2Fe(Ga0.5Ge0.5) (CFGG) full-Heusler alloy on its half-metallic electronic structure. First-principles calculations predict that the Co antisite defects that occupy Fe-sites (CoFe) lead to a finite DOS in the half-metallic gap of CFGG. Fe antisites defects in Co-sites (FeCo) introduced by excessing Fe composition, which could suppress the formation of CoFe, preserves the half-metallic gap but reduces spin polarization because the Fermi level shifts to the lower energy. We found that, in Fe-excess CFGG, Ge-excess has an important role to enhance the spin polarization by lifting up the Fermi level position and suppressing the formation of CoFe. To confirm the effect of the Fe and Ge-excess off-stoichiometric composition on spin polarization and phase-purity experimentally, we fabricated CFGG epitaxial thin films with various composition ratios (Co2−αFe1+α) (Ga1−βGeβ)1+γ with small positive γ (=0.09–0.29). It turns out that Co1.75Ge or Fe1.7Ge secondary phase often forms in the films for β ≥ 0.69 in Fe-deficient (α ≤ 0.21) and excess (α ≥ 0.49) compositions. This secondary phase can be suppressed by tuning the Ge and Fe compositions, and the L21-phase pure film was found in Co39.4Fe29.3Ga13.4Ge17.9 (α = 0.28 , β = 0.57 , γ = 0.25). The measurements of conventional magnetoresistance effects qualitatively indicate higher spin polarization in the Co39.4Fe29.3Ga13.4Ge17.9 film compared to other Co-excess and Ge-deficient films, which evidences the benefit to make Fe- and Ge-excess off-stoichiometric CFGG for obtaining the half-metallic nature of CFGG. [ABSTRACT FROM AUTHOR]

Half-metallic ferromagnetic Heusler alloys attracted much attention in the last few decades due to their significant physical properties as well as its potential applications in spintronic devices. To explore and predict the various physical properties of Co-based Heusler alloy, Co2MnSi (CMS), First principles calculations are of interest and has been used in the present study. Optimized E–V curves represent that CMS alloy is most stable in its magnetic L21 structural phase. The electronic charge density plot represents the ionic bonding along with co-valent character for the compound. DOS and BS calculations shows 100% spin polarization at Fermi level (EF) which confirms the half metallic character of the compound. DOS exhibited the prominent role of Co-3d and Mn-3d electronic states along with Si-2p electronic states. Estimated magnetic moment of Co2MnSi Heusler alloy was found to be ~ 5μB per f. u. which is in line with the Slater-Pauling behaviour. Dynamical stability of Co2MnSi Heusler alloy has also been verified by the phonon dispersion curves which revealed that compound is dynamically stable. Additionally, the physical properties have also been explored as a consequence of SOC and significant changes in electronic and optical properties were observed. The observed significant results of electronic, magnetic, and optical properties of CMS Heusler alloy makes it promising towards potential application in optical and spintronic devices. [ABSTRACT FROM AUTHOR]

This paper will focus on the comparative study of the structural, electronic, magnetic, optical, and thermoelectric properties of the two Heusler systems Ag2TiGa and Ag2VGa in the inverse L21 Hg2CuTi structure. Using the density functional theory‐based wien2k code, which implements the computational methods used in this study, namely GGA, GGA‐mBJ, GGA + U, and GGA + SOC (spin‐orbit coupling). The band structures show that all two structures studied are metallic. The spin density of states of Ag2VGa has evident spin splitting near the Fermi level, and the total magnetic moment of the Ag2VGa structure is 2.19 μB, which indicates that Ag2VGa is magnetic. The full‐Heusler Ag2VGa material can be used as spintronic materials due to their high spin polarization (about 50%). While Ag2TiGa has low polarization so it is bad electronically, but better thermoelectrically than Ag2VGa. So, the full‐Heusler Ag2TiGa material may also be considered as a potential candidate for thermoelectric applications at room temperature. Studies of the two new Heusler alloys may provide a theoretical reference for subsequent theoretical research and experimental synthesis of Ag‐based Heusler alloys. [ABSTRACT FROM AUTHOR]

We have looked at a very interesting class of Heusler alloy that has received a lot of theoretical research but a very little experimental attention. Mn2TiSi Heusler alloy was synthesized by a conventional vacuum arc remelting process. The formation of Heusler phase along with the secondary phases was observed after annealing it at 773 K for 120 h. The X-ray diffraction pattern illustrates the presence of cubic B2 disordered phase along with a secondary phase with a lattice parameter of 5.82 Å. The microstructure and compositional analysis of Mn2TiSi alloy shows the presence of distribution of Mn, Ti, and Si elements according to their stoichiometric ratio. The magnetic measurements show a ferromagnetic nature with Curie temperature (TC) around 203 K. With low magnetic moment and coercivity, Mn2TiSi can be used for switching applications because of its fast magnetization reversal. So, Mn2TiSi becomes the greatest choice for use in spintronics due to its low magnetic moment and low coercivity. [ABSTRACT FROM AUTHOR]

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]

We predict a series of XYZ-type half-Heusler RuMnZ (Z = Si, Ge, Sn, P, As, Sb, Se, and Te) alloys, using density functional theory (DFT) calculations. Structural, electronic structure, magnetic moments, and elastic properties are carried out using both GGA and GGA+U approximations to determine the viability of this series of alloys for spintronic applications. The band structure (BS) and density of states (DOS) calculations are carried out to explain the half-metallic and magnetic nature of the predicted alloys. RuMnZ alloys stabilize to the F 4 ¯ 3 m space group with a ferrimagnetic (FiM) ground state, with the exception of RuMnSn, which has a ferromagnetic (FM) ground state. Interestingly, RuMnP/As/Te alloys exhibit half-metallic properties with 100% spin polarization at the Fermi level among the predicted alloys. When U is included in the calculations (GGA+U), the half-metallicity is completely lifted. Further, upon incorporating pressure under GGA+U, a band gap is induced again, and the half-metallicity in RuMnTe is robust up to a compressive pressure of 140 GPa. Calculation of the elastic properties shows that RuMnZ has a ductile nature. [ABSTRACT FROM AUTHOR]

In this work, the structural, electronic, elastic, optical, and magnetic properties for the B1, B2, and B3 phases of Sr0.875Mn0.125O with relaxed structure (RS) and unrelaxed structure (URS) are investigated. The investigations are accomplished by the adoption of first‐principle methods established on spin‐polarized density functional theory, based on the full‐potential linearized augmented plane wave method as implemented in the WIEN2k code, where the electronic exchange‐correlation potential is studied by the Perdew–Burke–Ernzerhof generalized gradient approximation (GGA‐PBEsol) and the revised TB‐mBJ rapprochement. The negative formation energy and elastic constant that are acquired indicate the thermodynamical and mechanical stability of all these structures. The ternary Sr0.875Mn0.125O alloys for all structures show half‐metallic ferromagnetic behavior with a spin polarization of 100 % at the Fermi level, except the B2 phase without unrelaxed structure (URS). The total magnetic moments are 5 µB for all compounds and the interaction is ferromagnetic between Mn─Sr and Mn─O sites. Optical properties such as refractive index and the optical reflectivity for these alloys are computed and discussed. These materials are half‐metallic ferromagnets, and they can be desirable applicants for spintronics implementations and ultraviolet spectra. [ABSTRACT FROM AUTHOR]

Based on the first principles of the generalized gradient approximation method, the magnetic and optical properties of Fe-, Ni-doped and (Fe,Ni) co-doped LiNbO 3 crystals are studied. The results show that the mono-doped LiNbO 3 crystals contain magnetic atoms (Fe,Ni) leading to spin polarization, and (Fe,Ni) co-doped LiNbO 3 crystals tend to the ferromagnetic state with △ E F M of − 143 meV. The total magnetic moment of the (Fe,Ni) co-doped LiNbO 3 crystal is 5.97 μ B , and the local magnetic moments of Fe and Ni are 2.99 μ B and 0.93 μ B , respectively. It is interesting that the introduction of the Ga atom makes the ferromagnetic state (△ E F M of − 285.4 meV) of the (Fe,Ni) co-doped LiNbO 3 system more stable than the anti-ferromagnetic state. Although Ga atoms do not contribute to the magnetic moment, the (Fe,Ni,Ga) co-doped LiNbO 3 is more conducive to the spin-polarized state. In addition, with the introduction of Fe, Ni, and Ga atoms, the visible region absorption changes significantly. Non-volatile holographic storage can be achieved by (Fe,Ni) co-doped LiNbO 3 , thus increasing the absorption of the visible light range. In summary, this research provides theoretical guidance for the application of LiNbO 3 crystals in spintronic devices. [ABSTRACT FROM AUTHOR]

Inspired by potential application prospects of spintronics and valleytronics, a novel heterobilayer Janus structure is designed by replacing the chalcogenide atomic layers in the original bilayer MoS2. Based on first-principles calculations, it is found that the SMoS/SeMoS structure exhibits a direct band-gap semiconductor and a typical type-II band alignment with longer carrier lifetime. The transition metal (TM) atom represented by V/Cr/Mn can be stably adsorbed on the heterobilayer Janus SMoS/SeMoS sheet and effectively introduce magnetic moments (m). The calculation results demonstrate that the most stable adsorption site of the TM atom is CX(A), and the TM (V/Cr/Mn) adatom modified SMoS/SeMoS system is converted into metal (V-) or half-metal (Cr/Mn-), respectively. Under the coupling of different indirect exchange interactions, the structure exhibits stable intrinsic anti-ferromagnetic interactions for V-SMoS/SeMoS and ferromagnetic ground state for Cr/Mn-SMoS/SeMoS, respectively, and the magnetic transition temperature (T c) reaches a high temperature or even room temperature. Moreover, the robust out-of-plane magnetocrystalline anisotropy energy ensures stable long-range magnetic order. Specifically, the combination of spin injection and strong spin–orbit coupling interaction effectively breaks the time-reversal symmetry, which leads to valley polarization of the system. Based on this, the biaxial strain can effectively regulate the electronic structure, magnetic properties and valley polarization of TM-SMoS/SeMoS nanosheets with double breaking of spatial-inversion and time-reversal symmetry. [ABSTRACT FROM AUTHOR]

A subclass of ternary intermetallic known as Heusler compounds is being employed in the steel industry to increase material strength. This study examines the structural, electrical, optical, and magnetic properties of Co2VZ (Z=Al, Bi, Ge, Si) compounds using two different methods. First is full potential linearized augmented plane wave (FP-LAPW) method by WIEN2k and second is pseudo potential method by Atomic Tool Kit-Virtual Nano-Lab. The equivalent energy gaps in the minority-spin of Co2VZ (Z= Al, Bi, Ga, Ge) with WIEN2k code, which displays 100% spin polarization, are 0.703, 0.384, 0.186, and 0.67 eV near to the Fermi level. Furthermore, it is discovered that these compounds are absolutely half-metallic ferromagnetic (HMF). With the exception of Co2VBi, which exhibits metallic properties, the aforementioned compounds exhibit 0.525, 0.0, 0.553, and 0.786 eV band gaps in the ATK-VNL code and indicate 100% spin polarization. The magnetic moments of the compounds Co2VZ (Z= Al, Bi, Ga, Ge) are found to be 2.976, 4.003, 1.989, and 3.001 µB, respectively, in the WIEN2k code. The relative magnetic moments of the aforementioned compounds are also 1.991, 3.947, 1.999, and 2.997 µB, according to the ATK-VNL code. [ABSTRACT FROM AUTHOR]

Density functional theory in the framework of generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof to investigate the effects of some selected transition metal (TM) and rare‐earth metal (RE) dopants on the electronic and magnetic properties of a 2D molybdenum disulfide (MoS2) monolayer is reported. The results demonstrate that it is energetically stable to incorporate Ni and Cu in MoS2 structure under Mo‐rich conditions. The pristine MoS2 monolayer has a calculated direct bandgap of 1.70 eV and experiences significant reduction in the gap due to the defects. There is observed induced magnetic behavior due to the tight binding effect originating from the localized dopants and the nearest‐neighbor Mo atoms, with magnetic moments ranging between 0.82 and 3.00 μB. Some of the dopants result in 100%$$ spin polarization which is useful for engineering spin filter devices on magnetic MoS2 nanostructures. [ABSTRACT FROM AUTHOR]

The structural, elastic, electronic, and magnetic properties of the CrCoSi, MnCoSi parent half-Heusler (HH) alloys, and their CrMnCo2Si2 derivative double half-Heusler (DHH) compound are studied, utilizing the augmented plane wave method, which is based on density functional theory and implemented in the WIEN2k code. The stability of HH structure of the CrCoSi and MnCoSi alloys has been checked for their non-magnetic and ferromagnetic phases, leading to that the latter phase of the type I arrangement is the most stable. The CrMnCo2Si2 DHH alloy, derivative from the found structural and magnetic ground states of CrCoSi and MnCoSi HH alloys, is constructed and investigated. This DDH as well as its CrCoSi parent HH are found to be resistant to deformation and can be classified as ductile materials, whereas the MnCoSi compound is brittle. By the gradient generalized approximation (GGA), the electronic structures of CrCoSi, MnCoSi, and CrMnCo2Si2compounds exhibit a metallic behavior in the spin-up channel and a semiconducting behavior in the spin-dn channel, with band gaps (half-metallic gaps) of 0.851(0.020), 0.852(0.021), and 0.531(0.002) eV, respectively. The half-metallicity of CrMnCo2Si2 DHH is retained with smaller (larger) band gap (half-metallic gap) of 0.38(0.106) eV than that of GGA, using GGA + U approximation. In addition, the total magnetic moments are found to be 1, 2, and 3 µB for CrCoSi, MnCoSi, and CrMnCo2Si2, respectively. Therefore, these alloys can be good candidates for spinitronic applications due to their half-metallicity. [ABSTRACT FROM AUTHOR]

Heusler compounds have generated significant interest in spintronics due to their unique features. The structural stability, electronic structure, magnetic, and elastic properties of Heusler alloys VXRh2 (X = Sn, Ge, and Si) are investigated using first‐principles calculations of density functional theory in the Quantum Espresso code. The alloys exhibit three magnetic states (nonmagnetic, ferromagnetic, and ferrimagnetic) and several structural phases (face centered cubic (FCC) and tetragonal). It is found that pressures below 0 GPa produce the FCC phase, while greater pressures produce two tetragonal phases. VSnRh2 is a ferromagnetic metal, while VSiRh2 and VGeRh2 exhibit excellent half‐metallic ferromagnetism. The equilibrium lattice constants of VSiRh2 and VGeRh2 are stable against changes, making these Heusler alloys ideal for spintronic devices. Elastic constant computations show that compounds are mechanically stable. [ABSTRACT FROM AUTHOR]

Here, we report the experimental investigations on magnetic (spin polarization and exchange bias) and transport (spin-flip and spin-flop) properties of Co2FeSi Heusler compound at cryo temperature and high magnetic field. The spin cluster characteristic of the material is revealed by the M[T] curve of the ZFC, FC, and FW cycles. This can exhibit spin polarization behavior of anti-ferromagnetism (AFM) at 30–70 K. Furthermore, at a critical field of 0.2 T, AFM transforms into ferromagnetic (FM) and on further increasing the magnetic field, the spin polarization region becomes linear due to perseverance of FM behavior. The isothermal magnetization [M(H)] are also evaluated at different temperatures and AFM to FM transition has been observed at various applied magnetic fields. These magnetic measurements are used to determine exchange bias [EB] parameters such as HE, HC, and Mr both at low and room temperature. The resistivity [ρ(T)] has been measured at 0 and 5 T field, which explain the increasing trend of metallic nature at cooling cycle and also provides a clear evidence of magnonic, phononic resistivity and spin-flip scattering. [ABSTRACT FROM AUTHOR]

Half-metallic Heusler alloys have been intensively studied in recent years due to their potential applications in spin-based devices, e.g., in magnetic tunnel junctions. Yet, their properties may be very sensitive to the choice of the substrates, i.e., to the epitaxial strain and interface properties. Here, we report the results of our computational work on the half-Heusler compound CrMnSb(1−x)Px. In particular, we demonstrate that the parent compound CrMnSb is close to a half-metallic material at the optimized lattice parameter, with the onset of the half-metallic bandgap a few meV above the Fermi energy. Moreover, although it undergoes a half-metallic transition under a uniform compression of ∼1.5%, such a transition is absent under epitaxial strain. At the same time, we show that a half-metallic transition could be induced by a chemical substitution of Sb with P, which results in a volume reduction of the unit cell. In particular, 50% substitution of Sb with P leads to a robust half-metallicity in CrMnSb(1−x)Px, with 100% spin polarization being retained at a large range of epitaxial strain. Thus, our results indicate that CrMnSb0.5P0.5 could be grown on different types of substrates, e.g., GaAs, without its electronic properties being detrimentally affected by biaxial strain. In addition, CrMnSb0.5P0.5 exhibits a fully compensated ferrimagnetic alignment, which could be potentially useful in applications where stray magnetic fields are undesirable. [ABSTRACT FROM AUTHOR]

A highly spin-polarized electron beam is extracted via field emission from a ⟨100⟩-oriented Heusler alloy Co2MnGa emitter, which is fabricated through ion milling of a crystallized thin film and well characterized through H2-promoted field evaporation and field ion microscopy (FIM). Crystalline facets of low-index planes such as the (100) and {011} planes can be observed as ring structures in the H2-Ne FIM images, despite the ternary nature of the alloy. The well-defined (100) surface at the emitter apex is the emission site, having higher emission current than other locations. The maximum spin polarization of the field-emitted electrons from the Co2MnGa(100) surface is 61%–76% and can be observed under a 1-nA probe current at 44 K. Although decreased spin polarization is observed with elapsed time, cleaning performed by the field evaporation process restores the spin polarization to the initial value. The spin polarization of more than 60% obtained even at room temperature surpasses those previously reported for transition metals such as Fe, Co, and Cr on W tips. [ABSTRACT FROM AUTHOR]

The changes in the magnetic and half-metallic characters of the structures formed by the doping of Ag, Cd, Y, Zr, and Nb atoms at the ratios of x = 0.25 and 0.125 to WSn alloy were investigated. While the spin-up states of all alloys showed metallic character, energy band gaps were observed in the spin-down states, except YSn alloy. Of the 10 structures, 84.10% spin polarization was obtained only in the Zr0.25W0.75Sn alloy, and the spin polarizations were 100% in all remaining alloys. Band calculations were made with both GGA and GGA + mBJ methods. When the GGA + mBJ method was used, an increase in band gaps was observed in proportion to the increase in Fermi energy levels. In addition, the obtained 3, 4, 5, 6, 7 μB/f.u. magnetic moments for M0.25(M = Ag, Cd, Y, Zr, Nb)W0.75Sn alloys, respectively, and the calculated magnetic moment per unit formula of 5.5, 6, 6.5, 7, 7.5 μB/f.u. for M0.125(M = Ag, Cd, Y, Zr)W0.875Sn alloys support their fields that can be used in spintronic applications. The magnetic moment values obtained with GGA-U (U = 1, 2, 3, 4 eV) calculations showed that while the magnetic moment values of Zr0.25W0.75Sn and Nb0.25W0.75Sn alloys were preserved, they directly increased the magnetic moments of some alloys. These high ratios of polarization, band gaps, and magnetic moments make all alloys ideal materials for use in spintronic applications. [ABSTRACT FROM AUTHOR]

The current study examines two quaternary Heusler alloys, CoNbMnZ (Z = As, Sb). The structural optimization displays a Y2‐type structure with a ferromagnetic feature as a stable state. Mechanical characteristics, cohesive, and formation energies further support the stability of these materials. The generalized gradient method band structure depicts the metallic character of both alloys. Upon integrating the modified Becke–Johnson potential to the generalized gradient method, the alloys signify a spin gapless semiconducting nature (SGS). The origin of the spin gapless property is explained using constituent hybridization through schematic representation. Since SGS alloys have zero spin‐flip energy, both holes and electrons display 100% spin polarization, making them ideal candidates for spintronics applications, which is a unique property of these alloys. Both alloys have a magnetic moment 2μB following the Slater–Pauling rule MT = ZT − 24. Furthermore, the computed thermoelectric properties suggest that these alloys are thermo‐efficient, might generate thermoelectric power, and act as green energy materials. [ABSTRACT FROM AUTHOR]

In our previous works [J. Phys. Chem. Solids 163 (2022) 110600], the CrLaCoAl alloy had been predicted to be half-metallic ferrimagnet with high Curie temperature, and it met the dynamic, mechanical and thermal stabilities. Furthermore, a smaller convex hull indicated that it was likely to be prepared in experiment. However, the half-metallicity of CrLaCoAl alloy is possible to be destroyed by defect. Therefore, it is necessary to study the stability, electronic and magnetic properties of defective CrLaCoAl. Results show that the formation energies of the Cr–La, Co–Al swap and Al(Cr), Co(La) antisite are negative, indicating that they are likely to be formed in the process of crystal growth. Among them, the formation energy of the Al(Cr) antisite is the lowest in defects, and the spin polarization is as high as 93.72%. In addition, the spin polarization of all antisites is over 60% except for the Cr(Al), La(Cr) and La(Al) antisite. High spin polarization in defect is favorable in spintronic application. [ABSTRACT FROM AUTHOR]

The ab initio investigations of Mx (M = Y, Zr, Nb)–Sc1-x–Sn diluted ternary alloys were calculated for x = 0.25, 0.125, and 0.0625 ratios in GGA and GGA + mBJ methods. Half-metallic band gaps were observed in the spin-up electron states. Only the spin-up electrons of the Nb0.25Sc0.75Sn alloy cut the Fermi energy level and reduced the spin polarization amount to 75.24%. Band gap values were also obtained in both GGA and GGA + mBJ methods. When the GGA + mBJ method was used, an increase was observed in the half-metallic characters of the alloys. Therefore, all the alloys were obtained as true half-metallic ferromagnetic materials. Total magnetic moment values were obtained as 4.00 μB/f.u. in all ratios of Y–Sc–Sn alloys. Since Y and Sc are in the same period, this result is expected for half-metallic alloys. While the total magnetic moment was 3.00 μB/f.u. for the 0.25 ratio in the Zr–Sc–Sn alloy, it was obtained as 3.50 μB/f.u. and 3.75 μB/f.u. for the 0.125 and 0.0625 ratios, respectively. While the total magnetic moment of the Nb0.25Sc0.75Sn alloy was obtained as 1.923 μB/f.u., the magnetic moment values increased to 3.00 μB/f.u. and 3.50 μB/f.u., respectively, when the amount of Sc increased. In short, considering both their electronic and magnetic properties, Mx (M = Y, Zr, Nb)-Sc1-x-Sn ternary alloys are quite suitable 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]

The first principle calculation to investigate the structural, optoelectronic, and magnetic properties of the Y2FeSi Heusler alloy (HA) using the Wien2K code has been discussed in detail in the present manuscript. To estimate the physical properties of the HA, PBE-GGA and mBJ exchange–correlation functional were applied. The electronic charge density contour plot represents the dominant ionic character among the atomic configurations of Y2FeSi compound. Density of states (DOS) across the Fermi level (EF) exhibits the prominent role of Fe-3d electronic states along with Y-4d and Si-2p electronic states. Estimated spin polarization (SP ~ 75%) from the DOS profile suggests the metallic nature with magnetic (ferromagnetic having magnetic moment ~ 1.65 µB/cell for the HA) ordering of the compound. Phonon spectra represents the dynamical stability of the Y2FeSi compound. Additionally, the consequence of spin–orbit coupling (SOC) on material's physical properties was also explored. Band structure (BS) with SOC effect shows additional energy levels across the EF, due to splitting of Y-atoms' energy levels. A dielectric function was assessed with and without SOC to study the optical properties. Overall, Y2FeSi HA reveals interesting electronic, magnetic, and optical properties that have the potential for application in optical and spintronic devices. [ABSTRACT FROM AUTHOR]

In this work, we have studied the structural, thermal, elastic and magnetoelectronic properties of FeNiMnZ (Z = Al, Si) Heuslers under pressure using the pseudo-potential plane wave method. The structural optimization was performed by considering three atomic arrangements in magnetic and non-magnetic states. It was found that FeNiMnZ Heuslers are chemically stable and crystallize in the ferromagnetic YI-type structure. At zero temperature (0 K) and zero pressure (0 GPa), the obtained lattice constant (a) and bulk modulus (B) are in good accordance with the literature. The determined elastic constants (Cij), Pugh's ratio (B/G), and universal elastic anisotropy index (AU) under pressure reveal that FeNiMnZ Heuslers are mechanically stable up to 76 GPa, behave in a ductile manner, and exhibit a notable elastic anisotropy, respectively. The band structure analysis shows that FeNiMnAl Heusler compound changes from perfect half-metallic to a metallic nature at 50.2 GPa, while FeNiMnSi Heusler compound keeps its metallicity throughout the considered pressure range. The spin polarization and total magnetic moment of FeNiMnAl (FeNiMnSi) material decrease under pressure varying from 50.2 to 88 GPa (from 0 to 80 GPa). Below 50.2 GPa, FeNiMnAl material exhibits 100% spin polarization and a total magnetic moment of 4μB, which makes it hopeful in spintronic applications. [ABSTRACT FROM AUTHOR]

The electromagnetic and electronic properties of six atomic terminations CrCr-ScFe-T, ZrSb-ScSn-T, CrCr-ScSn-B, ZrSb-ScFe-B, CrCr-ScFe-V, and ZrSb-ScSn-V in complete Heusler alloy Cr2 ZrSb/Sc2 FeSn (100) heterojunction were systematically studied by first-principles calculation based on density functional theory. The results show that the interactions between the interface atoms causes the unevenness of the interface atomic layer, which leads to the increase of the mechanical mismatch rate of the interface layer. Compared with the high spin polarization in the bulk, the spin polarization of the heterojunction is destroyed to varying degrees. Fortunately, the termination ZrSb-ScFe-B retains a high spin polarization value and has a tunnel magnetoresistance of 429.29% at low temperature according to the Julliere model, indicating its potential application prospects in spintronic devices. [ABSTRACT FROM AUTHOR]

The theoretical study of the thermoelectric properties of the FeV1-xMnxSb half-Heusler alloy (x = 0, 0.25, 0.5, 0.75, and 1) has been conducted using density functional theory. The aim of this research was to investigate the effect of Mn substitution on the FeVSb system in order to achieve a higher value of ZT. Our findings show that a system with an Mn doping concentration of x = 0:75 achieves the highest values of ZT ~ 0:90 for the spin-down states in the temperature range from 300 to 800 K, making it a promising candidate for future thermoelectric applications. On the other hand, the Mn substitution also triggers the magnetic moment formation and causes a large spin polarization at the Fermi level, leading the system to change from insulator to half-metallic. [ABSTRACT FROM AUTHOR]

Wire‐shaped materials are ideal form for rapid, cheap, and scalable production and application. Herein, the most recent results on Heusler‐based cylindrical micro‐ and nanowires are reviewed, emphasizing spintronic, magnetocaloric, and shape memory applications. Herein, how the Heusler alloy's composition can be tuned to achieve a material with repeatable magnetic and mechanical properties is showed. A wide range of possible Heusler compositions allows us to tune the structural transformation temperatures by alloying the original composition with a few percent of metalloid. Wire shape brings additional effect—well‐defined easy axis change due to a structural transformation that enhances the magnetocaloric effect at low‐magnetic fields. The unique wire's shape properties can be downscaled to nanoscale range by electrodeposition. It is showed that such a method allows the production of a highly ordered array of nanowires. As a result, the magnetocaloric effect of an array of nanowires can be one order higher than that obtained by other production methods, where the nanowires are oriented randomly. Finally, some possible applications of shape memory or magnetocaloric actuators and the possibility of implementing high spin polarization for the construction of spintronic devices are showed. [ABSTRACT FROM AUTHOR]

First principles calculations are performed to investigate the thermodynamical stability, dynamical, mechanical, electronic and magnetic properties of CrTiCoZ (Z = Al/Si) novel quaternary Heusler alloys. A Y-type III atomic configuration is found to be the most stable structure for both compounds. The lattice constant values obtained using GGA-PBE approach are 5.9368 Å and 5.7853 Å for CrTiCoAl and CrTiCoSi, respectively. Using the value of elastic moduli for both the compounds, the computed Pugh's ratio value is 2.5 and 2.7 for CrTiCoAl and CrTiCoSi, respectively, which is higher than 1.75, indicating both the compounds are ductile in nature. The melting temperatures of both compounds are as high as 2142 K and 2420 K for CrTiCoAl and CrTiCoSi, respectively. The electronic structure calculations, using the GGA-PBE approach, show a half metallic behavior of CrTiCoAl. The spin-down channel exhibits a direct band gap of 0.15 eV, whereas the spin-up channel is metallic, making CrTiCoAl a half metallic ferromagnet with 100% spin polarization and an appreciable magnetic moment of −2 μB. However, CrTiCoSi is found to be semi-metallic in the spin-down channel and metallic in the spin-up channel, which leads to a spin polarization of 99.7% with a non-integer magnetic moment of −0.99 μB. The Curie temperature of CrTiCoAl is well above the room temperature (385 K), whereas that of CrTiCoSi is below the room temperature (203 K). Thus, CrTiCoAl is found to be more promising than CrTiCoSi as a spin injector in spintronic devices. [ABSTRACT FROM AUTHOR]

We used density functional theory (DFT) calculations to investigate the structural, electronic, magnetic, mechanical, and thermodynamic properties of CoYSb (Y = Cr, Mo and W) compounds. These are XYZ type half-Heusler alloys, which also exist in the face centred cubic MgAgAs-type structure and conform to F 4 ¯ 3 m space group. We computed these properties in three different atomic arrangements known as Type-I, Type-II, and Type-III phases. In all these phases, the alloys were found to be in the ferromagnetic state. Furthermore, the calculated electronic band structure and the total electronic density of states indicated a metallic behavior in CoWSb, nearly half-metallic behavior in CoMoSb, and half-metallic behavior in CoCrSb, with a minority-spin band gap of 0.81 eV. Furthermore, the calculated mechanical properties predicted an anisotropic behavior of these alloys in their stable phase. Finally, due to its high Debye temperature value, CoCrSb shows stronger covalent bonding than CoMoSb and CoWSb, respectively. [ABSTRACT FROM AUTHOR]

Half-metallic Heusler alloys have attracted significant attention due to their potential application in spin-transport-based devices. We have synthesized one such alloy, CoFeV0.5Mn0.5Si, using arc melting and high-vacuum annealing at 600 °C for 24 hours. First principles calculation indicates that CoFeV0.5Mn0.5Si shows a nearly half-metallic band structure with a degree of spin polarization of about 93%. In addition, this value can be enhanced by the application of tensile strain. The room temperature x-ray diffraction patterns are indexed with the cubic crystal structure without secondary phases. The annealed sample shows ferromagnetic order with the Curie temperature well above room temperature (Tc = 657 K) and a saturation magnetization of about 92 emu/g. Our results indicate that CoFeV0.5Mn0.5Si has a potential for room temperature spin-transport-based devices. [ABSTRACT FROM AUTHOR]

We have carried out ab initio density functional theory (DFT) calculations on the DO3-type Cr3Z (Z = P, As, Sb, S, Se, and Te) alloys with the aim of predicting new half-metallic (HM) magnetic materials for potential spintronics applications. From the structural and magnetic calculations, we find that Cr3Z (Z = As, Sb, S, Se, and Te) alloys stabilized to ferrimagnetic (FiM) state, while Cr3P alloy stabilized in non-magnetic state. The spin-polarized density of states (DOS) calculation reveals that, among all the alloys, only the Cr3Sb exhibits HM-FiM nature at the equilibrium lattice constant with total integer magnetic moment of − 1 μB, satisfying the Slater-Pauling (S-P) rule and thus offering 100% spin polarization at the Fermi level. Further, both Cr3As and Cr3Te alloys show nearly half-metallic (NHM) behavior, while Cr3P, Cr3S, and Cr3Se alloys behave as usual metallic materials. Interestingly, in all the Cr3Z (Z = P, As, Sb, S, Se, and Te) alloys, the total magnetic moment is mainly contributed by Cr(Y) atoms. We also attempt to rationalize the origin for the observed HM band gap in terms of molecular orbital (MO) hybridization mechanism. Finally, the influence of sp atoms on the structural, electronic, magnetic, and half-metallic properties of Cr3Z (Z = P, As, Sb, S, S, and Te) alloys is studied systematically. [ABSTRACT FROM AUTHOR]

In this manuscript, we investigate the effect of structural disorder on the physical properties of Pd-based Heusler alloys: PdCoMnAl, Pd2CoAl and Pd2MnAl using first-principles calculations. In fact, we are studying the structural properties of the equatorial quaternary Heusler alloy PdCoMnAl for three phases: type 1, type 2 and type 3, we have carried out this property to determine the most stable phases. The structural properties results show that the phase of type I, of this alloy is the most stable configuration. In addition, the band structures, and density of states calculations results show that this compound exhibits a half-metallic character with a 100% of spin polarization (SP) at the Fermi-level. The total magnetic moment of the Heusler compound is found to be 5.00 µB. Moreover, it is found that the Slater-Pauling is well described for this alloy. On the other hand, concerning total energy of the full Heusler Pd2YAl (Y = Co or Mn) alloys. It is found that such material in L21-type structure is always smaller than in the XA-type structure during the whole lattice variation variety and the L21-type structure is more energetically preferable for the both full alloys. In addition, the density of states at the Fermi level within the spin up and down states show the metallicity of these compounds. Our results show that the quaternary Heusler is a potential candidate for the spintronic applications. [ABSTRACT FROM AUTHOR]

The electronic structure and optical properties of the Heusler alloys Co2NiGa, Co2NiAl, Co2FeGa, and Co2FeAl are reported and compared in this work. In the Fe-based alloys, Co2FeGa and Co2FeAl, the electronic structure is found to have 100% spin polarization with the indirect energy gap in the Γ - X direction, whereas in Co2NiGa and Co2NiAl, the density of states is metallic in both spin projections with spin polarization of 55% (Co2NiGa) and 37% (Co2NiAl). Total and Co partial magnetic moments of all Heusler alloys for the optimized lattice parameters were found in a good agreement with previous calculations and experimental data. The frequency dependence of the real and imaginary parts of the complex dielectric constant for the Heusler alloys is studied in the spectrum region of 0.08–5 eV. The research results are discussed based on the performed calculations of the electronic structure. It was found that the character of variations of the spectral parameters of the alloys is typical for media with the metallic conductivity. In the IR region, the mechanism of the intraband acceleration of electrons by the light wave field dominates. The significant changes in the optical spectrum, magnetic moment, spin polarization and electronic structure were revealed in Co2MGa and Co2MAl for different M atoms which motivate further investigations of the Co-based Heusler alloys as promising materials for spintronics. [ABSTRACT FROM AUTHOR]

The results of the optical properties study and the electronic structure calculation of ${\text{Co}}_{2}Y\text {Si}$ ($Y = \text {Ti}$ , V, Cr, Mn, Fe) Heusler alloys are presented. Temperature dependences of the electrical resistivity were studied in the temperature range from 4.2 to 300 K. Field dependences of magnetization were measured in the magnetic fields of up to 5 T. The main attention is paid to the spectral dependence of the real and imaginary parts of the dielectric constant in the wavelength range from 0.3 to $8~\mu \text{m}$ by the ellipsometric Beattie method at room temperature. Anomalous behavior of optical conductivity at infrared (IR) frequencies in Co2TiSi and Co2VSi alloys was found, which significantly differs from that in Co2MnSi, Co2FeSi, and Co2CrSi. The results obtained are discussed based on calculations of the electronic structure. Simultaneously, the correlations between the changes in these characteristics can be an indicator of the states of a half-metallic ferromagnet (HMF) or a spin gapless semiconductor (SGS). A high degree of charge carriers’ spin polarization is possible in such materials, and therefore, they are promising materials for spintronics. [ABSTRACT FROM AUTHOR]

The electronic structure and optical properties of the Heusler alloys Co2NiGa, Co2NiAl, Co2FeGa, and Co2FeAl are reported and compared in this work. In the Fe-based alloys, Co2FeGa and Co2FeAl, the electronic structure is found to have 100% spin polarization with the indirect energy gap in the Γ - X direction, whereas in Co2NiGa and Co2NiAl, the density of states is metallic in both spin projections with spin polarization of 55% (Co2NiGa) and 37% (Co2NiAl). Total and Co partial magnetic moments of all Heusler alloys for the optimized lattice parameters were found in a good agreement with previous calculations and experimental data. The frequency dependence of the real and imaginary parts of the complex dielectric constant for the Heusler alloys is studied in the spectrum region of 0.08–5 eV. The research results are discussed based on the performed calculations of the electronic structure. It was found that the character of variations of the spectral parameters of the alloys is typical for media with the metallic conductivity. In the IR region, the mechanism of the intraband acceleration of electrons by the light wave field dominates. The significant changes in the optical spectrum, magnetic moment, spin polarization and electronic structure were revealed in Co2MGa and Co2MAl for different M atoms which motivate further investigations of the Co-based Heusler alloys as promising materials for spintronics. [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]

• 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]