Search

In this work, CeO 2 nanocrystals with a mixture of distinct morphologies were obtained using different solvents (acetone or ethanol). The (micro)structural, sensing mechanism, and magnetic properties, as well as first-principle calculations were evaluated. XPS reveals that the sample synthesized in acetone exhibited a diminished Ce4+ content (and heightened Ce3+ concentration) compared to the sample synthesized in ethanol. In the case of the syntheses at acetone, sphere-like nanoparticles and nanorods present a predominance of surfaces (111) and (220), while the syntheses with ethanol led to a predominance of surfaces (200) for the sphere-like nanoparticles. Theoretical simulations reveal the spin polarization of f electrons in Ce ions neighboring oxygen vacancies suggests that oxygen vacancies situated at the surface may engender a greater number of magnetic moments compared to those induced by an oxygen vacancy within the bulk. At room temperature, the M S of CeO 2 nanocrystals crystallized in acetone (66.20 emu-g) surpasses that of the CeO 2 nanocrystals obtained in ethanol (24.07 emu-g), which can be attributed to the differing morphologies of the samples. Our findings illustrate that, in addition to the solvent type, the size and morphology of the particles also play a significant role in influencing the sensing mechanism and magnetic properties. Films based on CeO 2 nanocrystals synthesized via MAS using acetone and ethanol revealed a fast response time of 9.6 s and 12 s, with a recovery time of 45.6 s and 87.6 s towards CO gas, respectively, these phenomena are attributed to the presence of oxygen vacancies, which facilitate the adsorption of CO. Our findings are key for facet engineering and may provide new strategies for producing CeO 2 based-materials to be applied in morphology-dependent technologies, such as carbon monoxide (CO) gas sensors. [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]

[Display omitted] • PtSe 2 monolayer is a non-magnetic indirect-gap semiconductor 2D material. • Either half-metallic or magnetic semiconductor natures are induced by doping with TMX n clusters. • Magnetic properties depend on the spin ordering in the incorporated clusters. • TMN n clusters act as charge gainers, meanwhile TMP n clusters lose charge. • Efficient methods to make new highly spin-polarized 2D materials towards spintronic applications are proposed. In this work, doping with TMX n (TM = Mn and Fe; X = N and P, n = 3 and 6) clusters is proposed to modify the electronic and magnetic properties of PtSe 2 monolayer. Pristine PtSe 2 monolayer is a non-magnetic two-dimensional (2D) semiconductor material with indirect band gap of 1.40(2.01) eV obtained from PBE(HSE06)-based calculations. PtSe 3 -type multivacancies lead to the monolayer magnetization with total magnetic moment of 0.54 μ B , where Pt and Se atoms around defect sites produce mainly the system magnetism. In contrast, no magnetism is induced by PtSe 6 -type multivacancies. The substitutional incorporation of TMX n clusters magnetizes significantly PtSe 2 monolayer, where both TM and X atoms originate mainly the magnetic properties. Depending on the spin orientation in the clusters, total magnetic moments between 0.00 and 8.00 μ B are obtained. All the doped D TMX n systems exhibit strong spin polarization around the Fermi level, which is derived mainly from the outermost TM- 3 d , N- 2 p , and P- 3 p orbitals. Consequently, either half-metallicity or magnetic semiconductor behavior can be induced, depending on the nature of TMX n cluster. Further, the Bader analysis indicates that TMN n clusters act as charge gainers due to the more electronegative nature of N atoms in comparison with Se atoms, meanwhile TMP n clusters transfer charge to the host PtSe 2 monolayer. Our study may introduce the cluster doping in PtSe 2 monolayer as efficient method to create new highly spin-polarized 2D materials towards spintronic applications. [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]

The weak magnetic properties of Ni 0.25 NbSe 2 are attributed to the delocalized nature of Ni-3 d electrons and hence poor spin polarization. [Display omitted] • Ni x NbSe 2 with x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25 were synthesized and observed that Ni intercalation limit is 25 %, beyond which NiSe phase segregates. • A phase transition is observed beyond x = 0.20 in Ni x NbSe 2 with a 2 a o × 2 a o × 1 c o order superstructure. • Theoretical calculation on Ni 0.25 NbSe 2 shows that the magnetic spins are very weakly spin-polarized and the Ni-3 d states are more delocalized. • Magnetic measurements on Ni x NbSe 2 (x = 0.05, 0.1, 0.2, 0.25) shows very small magnetic moment at low temperature for all the compounds attributed to the delocalized nature of Ni-3 d electrons, which is conformed from the theoretical studies. The article presents the synthesis, structural and magnetic properties of Ni x NbSe 2 (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25). The intercalation limit of Ni in NbSe 2 is found to be 25 mol%, above which NiSe appears as a binary impurity phase. Single crystal X-ray diffraction studies show that all the compounds crystallize in the hexagonal P6 3 /mmc space group. However, there is a distinct phase transition beyond x = 0.20 with Ni intercalation in Ni x NbSe 2. The Ni x NbSe 2 compounds crystallized in the parent 2H phase with x value between 0 ≤ x ≤ 0.2. Subsequently, the phase transforms into the 2H(I) phase with an order superstructure of 2 a o × 2 a o × 1 c o for 0.20 ≤ x ≤ 0.25 in Ni x NbSe 2. The superstructure formation is attributed to the occupation of Ni at the alternate octahedral voids present in the van der Waals gap of the NbSe 2. The XPS results and theoretical analysis clearly show that the intercalation of Ni results in a more metallic character in Ni x NbSe 2. Magnetic measurements on Ni x NbSe 2 (x = 0.05, 0.1, 0.2, 0.25) shows very small magnetic moment at low temperature for all the compounds. Theoretical calculation on Ni 0.25 NbSe 2 shows that the Ni-3 d electrons are delocalized and are very weakly spin-polarized, which may be the reason for the experimentally observed weak magnetism in these compounds. [ABSTRACT FROM AUTHOR]

The FP-LAPW method is used to examine the physical properties of Fe–Pd binary intermetallic compounds. The calculated formation enthalpies indicate that FePd and FePd 3 compounds are thermodynamically stable in L1 0 and L1 2 phases, respectively, and the ferromagnetic Fe 3 Pd can be formed in a tetragonal Z1 structure with a small negative formation enthalpy. The elastic coefficients and their related parameters show that all compounds are mechanically stable and ductile in nature. The FePd-L1 0 is the harder compound and Fe 3 Pd-Z1 exhibits the highest anisotropy. The band structure, the TDOS profile and the charge density distribution show that these compounds are ferromagnetic with a metallic character and covalent-metallic bonds. The PDOS shows that the Pd- 4d and Fe- 3d states are dominant, and the asymmetry of Fe- 3d states is behind the system strong spin polarization. The calculated magnetic moments agree well with previous theoretical results. The thermodynamic parameters are determined using the quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]

[Display omitted] Incorporating magnetic species, magnetic functional groups or additives, into polymer hosts is an effective method for synthesizing magnetic polymers. Polymers can gain magnetic moments not solely through magnetic coupling but also via the induction of Coulombic excitation. Attachment of the magnetic side-groups to the polymer backbone increases orbital localization in repeat units. This will bring two competing effects. The orbital localization will increase the intra-site Coulomb interaction, which increases magnetic moments in repeat units. Oppositely, the orbital localization also increases the energy splitting between orbitals on the polymer backbone and on side-groups, suppressing thus the magnetic moments of repeat units. However, a preference for low-spin states in the polymer units emerges when a substantial split in orbital energy occurs due to a strong coupling, consequently suppressing the magnetic moment. On the contrary, a minimal split in orbital energy within the polymer units can readily induce a high-spin state and generate a magnetic moment. However, in such cases, the Coulomb interaction triggered by the interconnected magnetic moieties might be too weak to produce a magnetic moment in the polymer. To explore this trade-off, we have proposed a theoretical two-level model aimed at elucidating the decision-making process of experimentalists during the synthesis of magnetic polymers. We also found that the dimerization of the polymer backbone together with the phonon dependence of spin–spin interaction between near-neighbor repeat units increases magnetic moments. As the magnetic responses arising from Coulombic interactions in polymers are intricately linked to carrier density, properties of the magnetic polymers acting as an active layer of a field-effect transistor can be tuned by the gate field, which controls the charge carrier density in the transistor transport channel. [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]

[Display omitted] • The coupling effect of the BCC-B2 transition and Mn occupancies has been studied. • The BCC-B2 transition intensified the magnetic interaction between Fe and Mn atoms. • The increased covalent bonding component and Peierls stress enhanced the brittleness. • VEC, spin polarization, and Mn content correlate with the contradictory relationship. The magnetism-ductility contradictory relationship presents a significant challenge in the development of magnetic alloys. The impact of the BCC-B2 transition, along with Mn site occupancy, on magnetism and ductility have been investigated by using first-principles calculations. The calculations involved the evaluation of magnetic moments, density of states (DOS), phase stability and ductility of FeCoMn alloys. The results of binary alloys confirm the enhancement of magnetism due to the BCC-B2 transition. Furthermore, the ordering phase transition can strengthen the magnetic interaction between Fe and Mn atoms, which is associated with minimal variations in the density of states of Fe and Mn in the B2 structure. Regarding the ductility of FeCoMn alloys, two factors contribute to increased brittleness. Firstly, the increased covalent component in bonding, as a result of the strong hybridization between different elements, leads to an increased brittleness. Secondly, the increased Peierls stress provides a larger resistance to dislocation motion, which also contributes to the increased brittleness. Finally, the Pearson correlation coefficients and data analysis indicate that VEC, spin polarizations and Mn content provide major contributions to the contradictory relationship between magnetism and ductility. [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]

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 magnetism of LaFe x Ni 1- x O 3 are investigated based on the first principles. • A detail discussion of magnetic performance of FM and AFM in LaFe x Ni 1- x O 3 system. • LaFe x Ni 1- x O 3 undergoes a magnetic transition from FM to AFM when x increases to 0.5. • The magnetic moment of O atom increases with the increase of Fe doping concentration. The effect of different Fe doping concentration (x = 0.125, 0.25, 0.375 and 0.5) on electronic structure and magnetic properties of LaNiO 3 (LNO) have been performed on the spin polarization calculations based on first principles. The calculation results show that with the increase of Fe dopant concentration, LaFe x Ni 1- x O 3 undergoes a magnetic transition from ferromagnetism (FM) to antiferromagnetism (AFM). The net magnetic moments of LaFe 0.125 Ni 0.875 O 3 , LaFe 0.25 Ni 0.75 O 3 , LaFe 0.375 Ni 0.625 O 3 and LaFe 0.5 Ni 0.5 O 3 in the FM ground state are found to be 12.00 µ B /supercell, 16.00 µ B /supercell, 20.06 µ B /supercell and 23.96 µ B /supercell, respectively. In the magnetic configuration of AFM of LaFe x Ni 1- x O 3 (x = 0.125 and 0.375) with the nearest doping position, the asymmetric magnetic structure leads to the symmetry of the spin-ordered AFM network is broken, resulting in the generation of net magnetic moment of -3.06 µ B and 3.87 µ B. The net magnetic moment in LaFe x Ni 1- x O 3 mainly originates from transition metals (TM) Fe, Ni and magnetized O atoms. [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]

• An effect of oxygen vacancy on the electronic and magnetic properties of copper pyrophosphate compound was investigated using DFT calculations. • The vacancy presence reduced the gap width from 2.17 eV to 0.19 eV, changing its character from indirect to direct. • The oxygen vacancies slightly modify the spin polarization of d-orbitals of Cu atoms neighboring the vacancy, resulting in the non-zero total magnetic moment of 0.19 µB/FU. The effect of oxygen vacancies (V O) on the electronic and magnetic properties of copper pyrophosphate dihydrate Cu 2 P 2 O 7 *2H 2 O (CuPPD) semiconductors is studied employing the DFT-based ab initio pseudopotential method. Site preference for vacancy formation on the selected oxygen sublattices is analyzed. Investigations revealed that the V O vacancies led to narrow bands of hybridized Cu-3d and O-2p states within the energy gap of perfect CuPPD semiconductors, significantly reducing the gap width from 2.17 eV to 0.19 eV and changing its character from indirect to direct one. Calculations have shown that the vacancies have no significant influence on the ferrimagnetic structure of CuPPD. The magnetic properties are driven by local magnetic moments of Cu atoms pointed oppositely. The oxygen vacancies slightly modify the spin polarization of d-orbitals of Cu atoms neighboring the vacancy, resulting in the non-zero total magnetic moment of 0.19 µ B /FU (0.0 µ B /FU in perfect CuPPD). The study's main finding, which can be exploited in nanoelectronics, is that the controlled implementation of oxygen vacancies can regulate the energy gap of CuPPD semiconductors. [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 the structural stability and half-metallicity of the half-Heusler alloy CoMnSe via the density functional theory (DFT). The γ -phase ferromagnetic of CoMnSe is more energetically stable than other phases. The electronic and magnetic properties show that the CoMnSe is a false half-metal ferromagnetic with 98.10% spin polarization and a total magnetic moment of 4 μ B . This value is in good agreement with the Slater-Pauling rule and available data using the GGA method, whereas the GGA+U method shows it is a ferrimagnetic metal with 95.73% spin polarization, and the total magnetic moment is 4.01 μ B. The effects of Bulk strain and axial strain demonstrate that the relative change of total magnetic moment M t o t and spin polarization P of CoMnSe is almost negligible, indicating that the half-metallicity is strong against Bulk strain and axial strain. Using Monte Carlo simulations, a transition ferromagnetic-paramagnetic response is also studied. • CoMnSe alloy is mechanically and thermodynamically stable. • CoMnSe does not undergo martensitic transformation. • CoMnSe is found to be falsely half-metallic using GGA, while it is metallic using GGA+U. • The high spin polarization and Curie temperature make CoMnSe suitable for spintronic. [ABSTRACT FROM AUTHOR]

Silicon (Si) is the dominant material in the semiconductor industry with some novel properties, the introduction of germanium (Ge) and vacancies lead to special electronic and magnetic properties. In this work, the effects of spin-polarized electrons regulate the electronic and magnetic properties for substituted Ge in bulk crystalline Si (Ge Si) with vacancies and electrical charge states introduced are investigated based on first-principles calculations. It is found that the electron spin density of Ge-vacancy (GeV) and Ge-divacancy (GeV 2) complex structures is redistributed, the number of the defect energy levels is changed, and the magnetic moment on atoms appears when vacancies are introduced in Ge Si. In addition, the distribution of the defect energy levels in the band gap is affected by charge states (negative and neutral), resulting in changes in the degree of spin-splitting, orbital occupation and electron filling, energy levels degeneracy, and the magnitude of the magnetic moment. These results show that the spin polarization on Ge Si with vacancies and charge states, the number and the distribution of the vacancies around Ge, all play important roles in regulating the magnetic moments, magnetic properties, and the magnitude and distribution of defect energy levels. [ABSTRACT FROM AUTHOR]

Bilayer thin films of multiferroic oxide BiFeO 3 and metallic alloy Fe 97 Si 3 deposited by RF-magnetron sputtering have been investigated to understand spin polarized electron transport across bilayer interface. Effect of BiFeO 3 thickness variation on magnetic and magnetotransport properties of bilayer thin films has been analyzed. An induced unidirectional magnetic anisotropy in bilayer thin films has been observed by interface coupling between antiferromagnetic BiFeO 3 and ferromagnetic Fe 97 Si 3 spin magnetic moments. Increasing interface roughness with increase in BiFeO 3 film thickness has been found to be a regulatory factor for inducing in-plane unidirectional anisotropy and exchange interaction at bilayer interface. A high magnetic moment ∼315 emu/cc originated at room temperature by uncompensated interface spin density has been measured in 30 nm thick BiFeO 3 film. Magnetic inhomogeneities at interface give rise to a spin glass like phase responsible for spin flip scattering at bilayer interface. Enhanced low field magnetoresistance ∼30% in 60 nm thick BiFeO 3 film is ascribed to intensified scattering from disordered interface states with increasing BiFeO 3 thickness. Magnetodielectric measurements (applied magnetic field 1 kOe) have revealed five times increase in relaxation time of charge carriers inside grains confirming intergrain charge transport dominated by alignment of magnetic moments of nearby grains via exchange coupling. High value of magnetoresistance ∼46% in 60 nm thick film of increased grain size is due to enhanced critical length for charge transport. Observed room temperature magnetoresistive properties of BiFeO 3 /Fe 97 Si 3 thin films are critical for developing multiferroic antiferromagnetic based spintronic devices. Image 1 • High value of room temperature magnetoresistance ∼46% obtained in 60 nm thick BiFeO 3 is significant to develop AFM based spin filters. • Interface roughness was found a key factor to determine magntoresistive and magnetic properties of BiFeO 3 /Fe 97 Si 3 bilayer. • Soft magnetic alloy Fe 97 Si 3 has been integrated with Bismuth Ferrite for the first time to raise its magnetoresistance values by introducing Si scattering centers. • A significant increase in both high field magnetoresistance (HFMR) ∼ 46% and low field magnetoresistance (LFMR) ∼ 30% has been obtained at room temperature. • The above study is also important to develop multiferroic tunnel junctions and sensors functional at room temperature. [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]

We report a study on the influence of microstructure on the magnetic and electronic properties of nanoscale Sr 2- x La x FeMoO 6 materials. The temperature dependence of the saturation magnetization of the samples in the low temperature range follows the spin wave theory which is described by a T 3/2 law. The analysis of the temperature dependence of the conductivity of the sample with x = 0 shows distinct mechanisms of spin-dependent tunneling and spin-independent hoping channels. Up on La substitution, additional metallic-type conduction paths appear which reduces the resistivity of the samples and also changes its temperature dependence behavior. Spin polarization as a function of temperature was obtained via fitting the MR curves recorded at different temperatures using the spin-dependent elastic tunneling model with correction for the spin-independent conductance. At a temperature 5 K, the spin polarizations of the samples are found to be roughly proportional to the net magnetic moment. Moreover, their values are considerably higher than those derived from theoretical calculations for the double perovskite lattices with the same antisite disorder levels which reveals an inhomogeneous distribution of the antisite defects in the samples. The decay rate of the spin polarization with increasing temperature is faster for the samples with a larger amount of antisite defects. • Sr 2- x La x FeMoO 6 samples (x = 0 – 0.4) were prepared by using sol-gel method and heat treatment in H 2 atmosphere. • Temperature dependence of saturation magnetization follows the Bloch law (∼ T 3/2). • Electrical conduction mechanisms were analyzed. • Spin polarization values were determined based on magnetoresistance data in temperature range 5–300 K. [ABSTRACT FROM AUTHOR]

Highlights • We studied the structural, electronic and magnetic properties of transition-metal (TM) (Cr, Mn, Fe, Co, Ni and Cu) adatoms on WS 2 monolayer by performing first-principles calculations. • Based on the adsorption energy, TM atoms prefer to occupy the T W site, above the W atoms, for all the cases. • The results indicate that systems of Cr, Mn, Fe and Co adsorbed on WS 2 monolayer are magnetic, while in Ni and Cu atoms adsorbed don't have any magnetic properties. • The TM atoms are adsorbed chemically to the WS 2 layer. The obtained values of the total magnetic moment vary from 4 μ B to 1 μ B in case of Cr to Co adsorption, respectively, which agree with the Slater-Pauling rule. • Based on magnetic moment of 0.00 μ B , non-magnetic states are realized for Ni and Cu adsorption. More importantly, a high spin polarization of 100% at the Fermi level is achieved in the Cr, Mn, Fe and Co adsorption, which implies the potential for application in spintronic devices. Abstract Given the various applications of half-metals in the spintronics devises, we studied the structural, electronic and magnetic properties of transition-metal (TM) (Cr, Mn, Fe, Co, Ni, and Cu) adatoms on WS 2 monolayer by performing first-principles calculations. Based on the adsorption energy, TM atoms prefer to occupy the T W site, above the W atoms, for all the cases. The results indicate that systems of Cr, Mn, Fe, and Co adsorbed on WS 2 monolayer are magnetic, while in Ni and Cu atoms adsorbed don't have any magnetic properties. The TM atoms are adsorbed chemically to the WS 2 layer. The obtained values of the total magnetic moment vary from 4 μ B to 1 μ B in case of Cr to Co adsorption, respectively, which agree with the Slater-Pauling rule. Based on the magnetic moment of 0.00 μ B , non-magnetic states are realized for Ni and Cu adsorption. More importantly, the high spin polarization of 100% at the Fermi level is achieved in the Cr, Mn, Fe and Co adsorption, which implies the potential for application in spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract We have constructed an analytic formula to treat the perpendicular magnetic anisotropy energy in ferromagnetic metals with low symmetry, such as C 4 V and C 3 V. We find that the anisotropy energy is proportional to a part of the expectation values of the orbital angular momentum and magnetic dipole operator. Although the result is similar to the model proposed by Laan (1998) [2] , we have derived a concrete expression for the spin-flip virtual excitation process term, which can be dominant in atoms with small magnetic moments and/or small exchange splitting. Pt monatomic layer with proximity-induced spin polarization grown on Fe is an example of this. Other multilayer systems such as Co/Pd and Co/Ni, and bilayer systems such as Fe(CoB)/MgO can be discussed similarly. Moreover, the relation between perpendicular magnetic anisotropy energy and measurable physical parameters is discussed based on X-ray magnetic circular dichroism spectroscopy. Highlights • An analytic formula to treat the perpendicular magnetic anisotropy energy in ferromagnetic metals with low symmetry has been constructed. • We find that the anisotropy energy is proportional to a part of the expectation values of the orbital angular momentum and magnetic dipole operator. • We have derived a concrete expression for the spin-flip virtual excitation process term. [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 The electronic structures and magnetic properties of 6H-SiC doped with N, C vacancies (V C), Si vacancies (V Si) and Al are studied by first principles calculations. The results indicate that the N substituting C in 6H-SiC cannot order magnetism but V Si can introduce magnetic moments effectively. Ferromagnetism coupling is obtained in (N, 2 V Si)-codoped 6H-SiC. The ferromagnetism can be mainly attributed to the interactions between the 2 p orbitals of C atoms around Si vacancies. More interestingly, substituting Si with Al can enhance the ferromagnetic states in 6H-SiC in neutral states. We also studied the effect of charge on magnetic properties and provide an effective method of tuning magnetism in 6H-SiC. Highlights • The doping with N Si , V Si and (N C , V Si) can induce ferromagnetism in 6H-SiC crystal. • Ferromagnetism can be enhanced by Al substituting and charge. • The spin polarization is proposed as the origin of ferromagnetism. [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]

We derive the generalized chiral kinetic equations which are applicable to the fermions with arbitrary mass. We show how the dynamical magnetic-moment distribution function could lead to spin polarization and electric charge separation. We also show how the electric/magnetic moment distribution and pseudoscalar distribution could be induced by vorticity and electromagnetic field in global equilibrium. [ABSTRACT FROM AUTHOR]

The spin resolved electronic transport behavior of ZnO nanowires (ZnONWs) linked to electrodes is investigated using first principles calculations within Density Functional Theory incorporating the Hubbard (U) term. A defect (resulting from Zn vacancy) in ZnO, as well as the use of Ni electrodes, have a significant influence on the electronic structure properties. They improve the magnetic moment of the system and generate a spin-asymmetric spectra. The ZnONWs linked to the Ni electrodes are probed for spin resolved differential conductance and current. Although the spin down differential conductance curves have a similar trend, the variations in spin up conductance are dissimilar. ZnONW-based devices appear promising for prospective spintronic applications due to their nearly half-metallic behavior around the Fermi energy and acceptable spin polarization in current. • ZnO nanowires are promising for spintronic applications. • The magnetism in ZnO nanowire-based devices can be enhanced using a vacancy and/or Ni electrodes. • Spin polarization in current and DOS is appreciable. [ABSTRACT FROM AUTHOR]

First, I study the analogy between the magnetization of a material and the spin polarization of particles in a fluid. Using the relativistic version of the Barnett effect, i.e. the magnetization of a material induced by mechanical rotation, the spin polarization induced by thermal vorticity is obtained within a purely classical model, where spin is treated as an intrinsic magnetic moment and rotation is included as a non-inertial effect. I argue that since spin polarization induced by thermal vorticity can be obtained in a classical theory, it can not be dominated by quantum anomalies. Second, the spin polarization induced by magnetic field is obtained for a fluid at local thermal equilibrium using statistical quantum field theory. The obtained formula is valid beyond the weak field approximation and when contributions from the non-homogeneity of the magnetic field are small. The exact form of spin polarization is studied for a free Dirac field at global equilibrium, and, like magnetic susceptibility, it oscillates according to the de Haas - van Alphen effect. Finally, I briefly review how magnetic field contributes to the difference between the spin polarization of Λ and Λ ¯ observed in heavy-ion collisions. [ABSTRACT FROM AUTHOR]

In this paper, using first-principles calculations based on density-functional theory, the electronic structures, magnetic properties, and half-metallicity in the bulk and (001) surface of quaternary Heusler alloy CoNbMnSi are studied. For the bulk, the CoNbMnSi compound shows half-metallicity with a band gap of 0.5 eV in the down-spin direction at a equilibrium lattice constant of 5.88 Ǻ. At a similar equilibrium lattice constant, the half-metallicity confirmed in the bulk CoNbMnSi, is ruined at both NbSi- and MnCo-terminated (001) surfaces and subsurfaces. Based on the magnetic property calculations, the magnetic moments of Mn and Nb atoms at the (001) surfaces increase with respect to the corresponding bulk values, while the magnetic moment of Co and Si atoms decreases. The spin-polarization ratio clearly decreases below 75% for (001) surfaces and subsurfaces of the CoNbMnSi alloy. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of (ZnO) 12 clusters doped with Cr atoms have been investigated by using spin-polarized first-principles calculations. The exohedral a3 isomer is favorable than endohedral a2 isomer. The isomer a1 and a5 respectively have the narrowest and biggest gap between highest unoccupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) of 0.473 and 1.291 eV among these five monodoped isomers. The magnetic moment may be related to the local environment around the Cr atom that the a2 isomer whose total magnetic moment is 6 μ B while the other monodoped isomers which all isomers have nearly total magnetic moments 4 μ B . For Cr-doped (ZnO) 12 on a1 or a3 isomer, the DOS of spin-up channel cross the Fermi level E F showing a finite magnitude near the Fermi level which might be useful for half metallic character. For the bidoped cases, the exohedral isomers are found to be most favorable. Including all bipoed isomers of substitutional, exohedral and endohedral bidoped clusters, the total magnetic moment of the ferromagnetic (antiferromagnetic) state is 8 (0) μ B and the HOMO-LUMO gap of antiferromagnetic state is slightly larger than that of ferromagnetic state. The magnetic coupling between the Cr atoms in bidoped configurations is mainly governed by the competition between direct Cr and Cr atoms antiferromagnetic interaction and the ferromagnetic interaction between two Cr atoms via O atom due to strong p-d hybridization. Most importantly, we show that the exohedral bidoped (ZnO) 12 clusters favor the ferromagnetic state, which may have the future applications in spin-dependent magneto-optical and magneto-electrical devices. [ABSTRACT FROM AUTHOR]

Using first principles study, through Density Functional Theory combined with Non Equilibrium Green's Function Formalism, electronic properties of endohedral N@C 20 fullerene molecule joining Au electrodes (Au-N@C 20 ) was addressed in the presence of spin property. The electronic transport behavior across the Au-N@C 20 molecular junction was investigated by spin resolved transmission, density of states, molecular orbitals, differential conductance and current-voltage ( I-V ) characteristics. Spin asymmetric variation was clearly observed in the results due to single N atom encapsulated in the C 20 fullerene cage, where the N atom played an essential role in the electronic behavior of Au-N@C 20 . This N@C 20 based molecular bridge, exhibiting a spin dependent I-V variation, revealed a metallic behavior within the bias range from −1 V to 1 V. The induced magnetic moment, spin polarization and other relevant quantities associated with the spin resolved transport were elucidated. [ABSTRACT FROM AUTHOR]

Co 2 CrAl/GaAs slabs have been constructed to study the electronic structure and magnetic properties by Structeditor program implemented in WIEN2k Code. GGA and LDA parameterizations have been used for exchange correlation functions. The density of states, structure and magnetic parameters have been studied and analyzed. Co 2 CrAl/GaAs (1 1 1) surface shows 80% spin polarization within LDA parameterizations. Variation in spin polarization with varying projections is observed due to different surface terminations and bond length. Effect of capping layers of Au and Cu on the magnetic moment and spin polarization of Co 2 CrAl/GaAs for different surface projections has been studied. The DOS indicates that the spin polarization has enhanced for all surface projections within the GGA approximation for both capping layers. The magnetic moment also varies from the bulk value of 3µ B in Co 2 CrAl/GaAs surfaces. [ABSTRACT FROM AUTHOR]

The magnetic, electric and optical properties of BiFe 0.875 Cr 0.125 O 3 (BFCO) doped with aliovalent ions (Na + , Mg 2+ ) and isovalent ion (Al 3+ ) are investigated by the first principle spin-polarized density functional theory calculations. It is demonstrated that the substitution of M (M = Na + , Mg 2+ , Al 3+ ) for Fe can produce net magnetic moments of 3.0, 2.0 and 3.0 μB, respectively. Besides, Na + doped BFCO exhibits metallicity while Mg 2+ doped system behaves as half-metallicity. Systematic study of electronic structures show that this conversion from semiconductor (BFCO) to half-metal or metal is mainly attributed to the shifting of O 2p, Bi 6s, and Cr 3d states induced by doping with aliovalent Na + or Mg 2+ . Furthermore, the aliovalent ions doped samples express high static dielectric constants of 12.08, 29.44, large refractive indexs of 5.41, 3.46 and both their absorption edges near zero, suggesting advanced optical response in visible region of the doped samples. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, we have systematically investigated the structural, electronic and magnetic properties of blue phosphorene doped by group IV and VI atoms, including C, Si, Ge, Sn, O, S, Se and Te. All the doped systems are energetically stable. Only C, Si, Ge and O-substituted systems show the characteristics of spin polarization and the magnetic moments are all 1.0 μ B . Moreover, we found that C, Si, Ge and O doped systems are indirect bandgap semiconductors, while Sn, S, Se and Te doped systems present metallic property. These results show that blue phosphorene can be used prospectively in optoelectronic and spintronic devices. [ABSTRACT FROM AUTHOR]

Structural, electronic and magnetic properties of the nitrogenated silicene monolayer have been throughly investigated using first-principles calculations. Pristine silicene single layer adopts a low-buckled structure and presents zero-gap semimetal character with Dirac cone structure at K point. N-functionalized silicene monolayers exhibit strong asymmetry of the band structure. Both spin channels exhibit metallic character in a full-nitrogenated layer, while the half-nitrogenation induces the half-metallicity with a perfect spin polarization of 100% at the vicinities of the Fermi level. Our simulations assert that the spin-gapless semiconducting and magnetic semiconducting behaviors may be obtained by applying proper tensile strains to the half-nitrogenated single layer. Significant magnetization of the silicene monolayer is also produced by the N-based functionalization, where total magnetic moments of 2.74 and 1.00 (μ B) are obtained in the full- and half-nitrogenated layer, respectively. In addition, the magnetic ground states and their corresponding band structures will be also discussed. Interesting electronic and magnetic properties suggest that the nitrogenation of silicene monolayer may be an effective method to form novel 2D materials for spintronic applications. [ABSTRACT FROM AUTHOR]

In this study, density functional theory (DFT) showed that the electronic band profiles of CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co, and Ni) indicate their half-metallic character. The optimized magnetic energy curves in different magnetic phases demonstrated the type-I ferrimagnetic order of all the compounds investigated in this study. The magnetic exchange coupling constants were calculated between the Cu–B, B–Re, and Cu–Re site spins using the Heisenberg model. These interactions generate strong long range Cu(↑)B(↑)Re(↓) order through a super-exchange mechanism. In these perovskites, the anti-parallel moments of Re with B and Cu reduce the net magnetic moments and they are responsible for the ferrimagnetism. The Cu and B 3d-electrons are localized and responsible for the magnetism, and the Re 5d-electrons are delocalized and responsible for the metallic nature. Magnetic susceptibility analysis verified the results estimated using DFT and the Heisenberg model. Due to the 100% spin polarization around the Fermi level, high Curie temperature TC and ferrimagnetism are expected, thereby making these materials suitable for spintronic applications. • The half-metallic character of the CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co and Ni) was revealed by DFT. • Heisenberg model was used for the calculating of the magnetic exchange coupling constants. • It has been shown the perspectives of the CaCu 3 B 2 Re 2 O 12 (B = Mn, Fe, Co and Ni) in spintronic applications. [ABSTRACT FROM AUTHOR]

The metal–insulator like transition of the ferromagnetic (FM) state in Co 1 − x Fe x S 2 (0 ≤ x ≤ 0.7) with varying x is investigated using X-ray diffraction, Mössbauer spectroscopy, and magnetoresistance measurements. The linear decrease of unit cell parameter with x confirmed Fe substitution at the Co site. The room temperature Mössbauer study showed the absence of magnetic moment on Fe and both isomer shift and quadrupole splitting were found to vary linearly with x. The temperature-coefficient-of-resistivity (TCR) in the FM state became negative for x ≥ 0.15. For intermediate compositions i.e., x = 0.05 and 0.1, TCR changed from positive to negative (T ≤ T C) to positive with an increase in temperature. By studying the temperature-dependent and isothermal magnetoresistance data around the transition region, it was shown that resultant behavior could be arising due to changes in spin polarization over a broad temperature range. [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]

True half-metallic materials are among the most preferred material groups in spintronic applications with their 100% spin polarization. Perovskite materials have formed the basis of many semiconductor devices in recent years with their widespread technological use. In this study, Na 2 MgXO 6 (X = Co, Fe) perovskite oxides were obtained as true half-metallic materials, and the effects of the atomic displacements between Mg and Co/Fe atoms on electronic, magnetic and half-metallic characters were investigated. First, volume-energy optimization curves were calculated, and ferromagnetic phases were energetically more stable. Second, electronic calculations were performed, and semiconducting band gaps were seen in the up-spin states. The band gaps of Na 2 MgCoO 6 and Na 2 CoMgO 6 oxides were obtained as 0.531 eV and 1.1446 eV, respectively. Then atomic displacements between Mg and Co/Fe-transition metals happened and band gaps of Na 2 MgFeO 6 and Na 2 FeMgO 6 oxides were obtained as 0.487 eV and 2.142 eV, respectively. As can be seen, the atomic structure changes directly affected the band gaps. Additionally, GGA + U interactions were performed for electronic calculations. As a result of increasing U-interactions, band gaps decreased. It is possible to say that all band gaps change with the effect of atomic compositions. Finally, the total magnetic moments of Na 2 MgCoO 6 and Na 2 MgFeO 6 oxides were obtained as 5.00 μ B /f.u. and 6.00 μ B /f.u., respectively. Na 2 MgXO 6 (X = Co, Fe) oxides with half-metallic ferromagnetic features and high magnetic moment values are very useful materials for spintronic applications. • Na 2 MgXO 6 (X = Co,Fe) double perovskite oxides were obtained half-metallic ferromagnetic materials. • The total magnetic moments were obtained 5.00 μB/f.u. and 6.00 μB/f.u., respectively. • The band gaps were obtained as 0.531 eV and 0.487 eV, respectively. • The atomic displacements increased the band gaps to 1.446 eV and 2.142 eV for Na 2 CoMgO 6 , Na 2 FeMgO 6 oxides. [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]

Spinterface between fullerene C 60 and La 0 7 Sr 0 3 MnO 3 (LSMO) was studied by means of density functional theory. Co-existence of many different configurations was shown, and probabilities of their appearance were estimated. Dependence of composite properties on configuration and temperature was also investigated. Key role of transition metal atoms in both binding between composite compartments and magnetic ordering in C 60 molecule was discussed. The latter was suggested to be responsible for spin-polarized charge transport while overall magnetic moment of fullerene molecule is relatively small. [ABSTRACT FROM AUTHOR]

New rare-earth half-metallic ferromagnets X 0.75 Eu 0.25 O ( X =Ca, Sr and Ba) with the NaCl structure are predicted based on the first-principles calculations. These materials only have up-spin subbands at the Fermi level and their net magnetic moments are all 7.00 µ B per unit cell, which exhibits the evident half-metallic characteristics. Their energy gaps and half-metallic gaps are both wide so that they all have high Curie temperatures and stable half-metallicity, holding great potential applications in spintronics. From the calculated formation energies, it is possible to prepare Sr 0.75 Eu 0.25 O and Ba 0.75 Eu 0.25 O experimentally. However, it may be difficult to prepare Ca 0.75 Eu 0.25 O in experiments. The magnetic moments and the half-metallicity of X 0.75 Eu 0.25 O mainly originate from the spin-polarization of Eu 4f-orbitals, which are caused by the strong octahedral crystal field in the ligand compound ML 6 consisting of the Eu-ion and six O-ions around it. [ABSTRACT FROM AUTHOR]

We have studied the origin of the magnetism induced by a neutral cation vacancy in rocksalt ScN using ab - initio calculations based on spin density functional theory. Our results showed that Sc vacancy induces a total local magnetic moment of 0.50 μ B . The main contributors to this induced magnetism are the 2 p orbitals of nearest nitrogen atoms surrounding the vacancy. The spin polarization energy (defined as the energy difference between the spin polarized and non-polarized states) is well above the room-temperature energy. Furthermore, we have investigated the effect of an external strain on the induced magnetism. Our calculations showed that applying an external strain leads to a decrease of the stability of the magnetic state. Moreover, calculations of the magnetic interactions showed that the most stable configuration corresponds to the fifth nearest neighbor distance with a ferromagnetic state. Finally, using thermodynamic considerations, we demonstrated that the minimum defect concentration to achieve magnetic percolation cannot be reached at equilibrium conditions. However, we found that by applying an external strain, we could reduce the formation energy of the defect, achieving therefore the magnetic percolation. [ABSTRACT FROM AUTHOR]

Binary transition-metal pnictides and chalcogenides half-metallic ferromagnetic materials with zincblende structure, being compatible with current semiconductor technology, can be used to make high-performance spintronic devices. Here, we investigate electronic structures and magnetic properties of composite structure ( ( CrX ) 2 / ( YX ) 2 (X=As, Sb; Se, Te and Y=Ga; Zn) superlattices) of zincblende half-metallic ferromagnetism and semiconductor by using Tran and Blaha's modified Becke and Johnson (mBJ) exchange potential. Calculated results show that they all are half-metallic ferromagnets with both generalized gradient approximation (GGA) and mBJ, and the total magnetic moment per formula unit follows a Slater–Pauling-like “rule of 8”. The key half-metallic gaps by using mBJ are enhanced with respect to GGA results, which is because mBJ makes the occupied minority-spin p-bands move toward lower energy, but toward higher energy for empty minority-spin Cr-d bands. When the spin–orbit coupling (SOC) is included, the spin polarization deviates from 100%, and a most reduced polarization of 98.3% for ( CrSb ) 2 / ( GaSb ) 2 , which indicates that SOC has small effects, of the order of 1%, in the considered four kinds of superlattice. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic and elastic properties of the ternary chalcogenides KMnQ 2 (Q=O, S, Se, Te) crystals were investigated by means of spin-polarized density functional theory calculations. The 3 d orbitals of the Mn atoms were treated using the GGA+U approach. The calculated equilibrium structural parameters agree well with the experimental data. Based on the analysis of the spin-polarized band structures and density of states, we predict the half-metallic character of the studied compounds, with a half-metallic gap of 1.38 eV, 0.53 eV, 0.37 eV and 0.14 eV for KMnO 2 , KMnS 2 , KMnSe 2 and KMnTe 2 , respectively, and a total magnetic moment of 4.00μ B per unit-cell for all considered structures. The examined properties for the title compounds include also the single-crystal elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio. [ABSTRACT FROM AUTHOR]

The effects of transition-metal atoms doping and elastic strain on the magnetic properties of monolayer WS 2 are investigated by the first-principles calculation. Firstly, we investigate the magnetic properties of a series of 3d transition-metal atoms (from Sc to Zn) doped monolayer WS 2 . Our calculations show that doping of transition-metal atoms from Sc to Cr results in nonmagnetic states, while Mn, Fe, Co, Ni, Cu and Zn doping can induce magnetism in WS 2 monolayer. The localized nonbonding 3d electrons of TM atoms lead to the formation of magnetic moments. Meanwhile, our calculations indicate that the elastic strain can be used to manipulate the spin polarization of TM-3d orbital. Specifically, the magnetic moment of Fe and Co-doped monolayer WS 2 increase with the increase of tensile strain, while the magnetic moment of Mn, Ni, Cu and Zn-doped WS 2 monolayer initially increase and then decrease with the increase of tensile strain. On the other hand, the magnetic moment of Fe, Co, Mn, Ni, Cu and Zn-doped WS 2 monolayers decrease with the increase of compressive strain. While the magnetic moment of Sc, Ti, V and Cr-doped WS 2 monolayers remain 0μ B independent of tensile strain and compressive strain. [ABSTRACT FROM AUTHOR]

We calculate the electronic structure and magnetism of monolayer phosphorene doped by nonmagnetic atoms. O, S and Se impurities can induce the magnetic moment. O doping makes it become a spin-gapless semiconductor, but S and Se doping induces a half-metallic characteristic. The p orbital of dopant has a strong hybridization with P around impurities, which induces spin splitting of P and impurities. C induces a metallic character. B acts as n -type dopant and F results in p -type dopant. The magnetism of phosphorene doped by two O atoms strongly depends on the doping sites and distance between two O atoms. [ABSTRACT FROM AUTHOR]

We investigate the spin-polarized electronic and magnetic properties of bilayer SnSe with transition-metal (TM) atoms doped in the interlayer by using a first-principles method. It shows that Ni dopant cannot induce the magnetism in the doped SnSe sheet, while the ground state of V, Cr, Mn, Fe and Co doped systems are magnetic and the magnetic moment mainly originates from 3 d TM atom. Two types of factors, which reduce the magnetic moment of TM atoms doped in bilayer SnSe, are identified as spin-up channel of the 3 d orbital loses electrons to SnSe sheet and spin-down channel of the 3 d orbital gains electrons from 4 s orbital. The spin polarization is found to be 100% at Fermi level for the Mn and Co atoms doped system, while the Ni-doped system is still a semiconductor with a gap of 0.26 eV. These results are potentially useful for development of spintronic devices. [ABSTRACT FROM AUTHOR]