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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]

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]

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]

Using the first-principles full-potential linearized augmented-plane-wave method with the GGA-PBE approximations, we have explored the structural, elastic, electronic, and optical characteristics of Co2−xVxFeGe. Our investigation reveals that the compound Co1.25V0.75FeGe exhibits ideal half-metallic ferromagnetism. Additionally, the compound Co2−xVxFeGe exhibits different crystal structures depending on the value of x. At x = 0.25, it has a cubic structure with a space group of P-43 m. However, at x values of 0.50 and 0.75, it undergoes a transition to a tetragonal structure with respective space groups of P42/mcm N◦ (132) and P-42 m (111). In these tetragonal structures, the compound displays anisotropic mechanical stability. Moreover, as the concentration of V increases, the volume gradually increases. These properties are crucial in determining the material's suitability for use in optoelectronic devices. The electronic properties of most of the compounds displayed half-metallicity and 100% spin polarization, particularly for the composition x = 0.75. [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]

Theoretical studies of the role of exchange correlation effects in the prediction of the half-metallic properties of ferrimagnetic Mn2VAl and Mn2VSi Heusler alloys, which are of interest in spintronics, are presented. Electronic, magnetic, and structural properties are studied within the framework of density functional theory. It is shown that the correction for additional correlation effects makes it possible to reveal two states, which are close to each other in energy, but have different magnetic moments. The state with a low magnetization demonstrates a half-metallic character with 100% spin polarization, whereas the state with a high magnetization has a metallic character. [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]

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 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]

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]

The first-principle calculations of density functional theory were used to study the structural, electronic, magnetic, mechanic, and half-metallic behavior of Y2MnZ (Z = Al, Ga, In) within the spin generalized gradient approximation. These compounds can be experimentally synthesized due to their negative values of the calculated formation energies. Our calculations indicate that they are more stable in Cu2MnAl-type structure. The Hg2CuTi-type structure displays half-metallic characteristic with 100% spin polarization at the Fermi level. The value of calculated magnetic moment has an integer value of 2μB for Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure which well matches with magnetic moments predicted from Slater–Pauling rule. Therefore, the Y2MnZ (Z = Al, Ga, In) in the Hg2CuTi-type structure is predicted to be a candidate for possible spintronics applications. [ABSTRACT FROM AUTHOR]

Density functional theory has been used to study the structural, elastic, electronic, magnetic and optical properties of Ti2FeSb Heusler alloy using generalised gradient approximation implemented through the WIEN2k code. The cubic structure of Ti2FeSb is mechanically stable in the F-43m space group and shows elastic anisotropic properties with ductile nature. Ti2FeSb shows spin gapless semiconductor behaviour along with an indirect energy band gap (EG) of 0.10 eV along the Г-Χ in majority spin (γ-spin) band above the Fermi energy level (EF) and 0.90 eV in the minority spin (δ-spin) band at EF. The total magnetic moment is 3 µB at optimized lattice constant (ao) 6.32 Å and follows the Slater–Pauling curve for inverse Heusler alloys. Robustness of this material with respect to change in the value of ao is evident in the constancy of magnetic moment along with retention of the half metallic nature within a lattice variation ±4% from equilibrium value of ao. Reflectivity, optical conductivity, dielectric function, absorption coefficient and energy loss have also been investigated as a function of incident energy for this alloy. [ABSTRACT FROM AUTHOR]

In this paper, an ab initio study of the electronic and magnetic properties of CdS doped by the transition metal elements has been investigated. Based on the KKR-CPA method within the Generalized Gradient Approximation (GGA), we have calculated the total energy to determine the most stable state in the system and found it to be the ferromagnetic state for Ti, V and Cr-doped CdS, while it is the stabilization in spin glass states for Mn and Co cases. On the other hand, we have investigated and plotted the density of states (DOSs) which reveals that the doped compounds exhibit a half-metallic character. The spin polarization at Fermi level is estimated and found to be around 100%. Furthermore, we have identified the type of mechanism of exchange interactions being double exchange for all components except Mn case where we find that the responsible mechanism is the p-d exchange. The evaluation of the Curie temperature variation TC for the three components stable in the ferromagnetic phase revealed values greater than 300 K for most cases. The effect of the crystal field and the exchange splitting as a function of the concentrations values has been also investigated. Half-metallic substances are very interesting for spin-dependent electronics devices as they boost their magnetoresistance capacity. [ABSTRACT FROM AUTHOR]

We predicted the electronic structure and half-metallic properties of the Mn2XSb (X = Co, Fe) inverse Heusler alloys using the full-potential linearized augmented plane wave (FPLAPW) method. We used generalized gradient approximation (GGA) and GGA + U schemes to compute the electronic structure for both alloys. We employed the Tran and Blaha modified Becke–Johnson (TB-mBJ) potential to accurately estimate the band gap. The stability has been determined by calculating their formation energy and elastic constants under ambient conditions. Both alloys show a half-metallic ferromagnetic nature with a 100% spin polarization at the Fermi level. The calculated total spin magnetic moments of Mn2XSb (X = Co, Fe) alloys are 4 μ B and 3 μ B , respectively, which is a good agreement with the well-known Slater–Pauling rule of 24. The predicted Curie temperature for both alloys is greater than room temperature. The half-metallic and high spin polarization properties make them one of the promising candidates for spintronic device applications. [ABSTRACT FROM AUTHOR]

High-spin-polarized materials are the promising candidates in spintronic devices. Here, the spin-polarized electronic structure, magnetism, and mechanical properties of Ti2.25Co0.75Si and Ti2.25Co0.75Si0.5X0.5 (X = As and Sb) Heusler alloys were calculated by first-principles calculations. The results show that Ti2.25Co0.75Si and Ti2.25Co0.75Si0.5Sb0.5 are ferromagnetic half-metals with 100% spin polarization, while Ti2.25Co0.75Si0.5As0.5 is a zero-gap half-metal. The complete spin-polarized characteristics of Ti2.25Co0.75Si and Ti2.25Co0.75Si0.5X0.5 are confirmed to be robust to hydrostatic and uniaxial strains. The results of the elastic constants and phonon spectra demonstrate the mechanical and dynamic stabilities of Ti2.25Co0.75Si and Ti2.25Co0.75Si0.5X0.5 alloys. Furthermore, the magnetic anisotropy results show that the easy magnetic axis of Ti2.25Co0.75Si can be tuned from the in-plane direction to the out-of-plane one under the uniaxial strains. Ti2.25Co0.75Si and Ti2.25Co0.75Si0.5X0.5 (X = As and Sb) alloys are promising candidates for the potential application in spintronic devices. [ABSTRACT FROM AUTHOR]

In this manuscript, we study the structural, electronic, and magnetic properties of the equiatomic quaternary Heusler alloy ZnCdRhMn in the framework of the first-principle calculations and Monte Carlo simulations. In fact, we have investigated the structural, the magnetic, and the electronic properties of the Zn-based equiatomic quaternary Heusler alloy ZnCdRhMn using the ab initio method in the bases on the GGA approximation. On the other hand, the critical behavior of the equiatomic quaternary Heusler alloy ZnCdRhMn has been outlined by the Monte Carlo simulations. For this end, we apply the Metropolis algorithm. The objective of this work is to improve the competition between the austenitic and martensitic phases on the existence of magnetic and electronic properties of this alloy. The half-metallic behavior is only improved for the austenitic structure and 100% of spin polarization has been found. Moreover, a high curie temperature is found for this alloy for the austenitic phase. We can conclude that the austenitic structure of this alloy is useful for the spintronic device applications. [ABSTRACT FROM AUTHOR]

The physical properties of Fe2CoAl (FCA) Heusler alloy are systematically investigated using the first-principles calculations within generalized gradient approximation (GGA) and GGA+U. The influence of atomic ordering with respect to the Wyckoff sites on the phase stability, magnetism and half metallicity in both the conventional L21 and XA phases of FCA is focused in this study. Various possible hypothetical structures viz., L21, XA-I, and XA-II are prepared by altering atomic occupancies at their Wyckoff sites. At first, we have determined the stable phase of FCA considering various non-magnetic (or paramagnetic), ferromagnetic (FM) and antiferromagnetic (AFM) configurations. Out of these, the ferromagnetic (FM) XA-I structure is found to be energetically most stable. The total magnetic moments per cell are not in agreement with the Slater-Pauling (SP) rule in any phase; therefore, the half-metallicity is not observed in any configurations. However, FM ordered XA-I type FCA shows 78% spin polarization at the Fermi Energy (EF). Interestingly, the results of XA-I type FCA are closely matched with the experimental results. [ABSTRACT FROM AUTHOR]

In this manuscript, we investigate the physical properties such as the magnetic and the electronic properties of the Co-based equiatomic quaternary Heusler alloy CoYCrZ (Z = Si and Ge). These investigations have been performed by employing the Quantum Espresso code in the framework of density functional theory (DFT). The generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) is used for all these calculations. The band structures, and density of states calculations, show that all these materials CoYCrZ (Z = Si and Ge) exhibit a half-metallic (HM) behavior only for the structure type II. Moreover, this structure type II is found to be the most stable configuration for all these alloys. On the other hand, it has been found that the Slater–Pauling is well described for the compound CoYCrGe, only for the configuration type II. In particular, the equiatomic quaternary Heusler alloys CoYCrSi and CoYCrGe are found to be half-metallic for the structure type II. This is due to the fact that they have 100% spin polarization SP. Also, the existence of complete SP in the studied alloys is the reason for which these materials are useful for spintronic device applications. [ABSTRACT FROM AUTHOR]

The first principles calculations are carried out to understand the half metallic and ferromagnetic properties of Fe2−xCoxTiSi (x = 0, 0.5, 1, 1.5, 2) full Heusler alloys. The stable structure is predicted as L21 structure (Cu2MnAl phase). The lattice constant value of Fe2−xCoxTiSi Heusler compounds increases as the value of x increases. These alloys exhibit half metallic ferromagnetism (except Fe2TiSi) with small spin flip gap at the minority spin state. At high pressure, semiconductor to metallic phase transition is observed in Fe2TiSi while half metallic to metallic phase transition is observed in Fe1.5Co0.5TiSi, Fe1.0 Co1.0TiSi, Fe0.5Co1.5TiSi and Co2TiSi. The spin polarization of these compounds (except Fe2TiSi) is 100%. Hence, these compounds are suitable for spin injection devices in spintronics. [ABSTRACT FROM AUTHOR]

The superconducting characteristics of the spin-valve Co2Cr1 - xFexAly/Cu/Ni/Cu/Pb heterostructures are studied. It is found that the difference in the plots characterizing superconducting transitions at the parallel and perpendicular orientations of magnetizations in the ferromagnetic Heusler alloy layer (HA = Co2Cr1 - xFexAly) with a high degree of spin polarization and in the nickel (Ni) layer can be as large as 0.5 K. For all samples, the dependence of Tc on the angle between the magnetization directions of the ferromagnetic layers exhibits a deep minimum near the orthogonal orientation. This minimum results from the long-range triplet components of the superconducting condensate in a ferromagnetic material. At the perpendicular orientation of the magnetizations, the Heusler alloy layer with the high degree of spin polarization absorbs the spin-polarized Cooper pairs from the spacing between the Heusler alloy and Ni layers. [ABSTRACT FROM AUTHOR]

In recent years, Heusler alloys have attracted extensive attention because of their usefulness in spintronic devices. In this paper, the structural, electronic, and magnetic properties of full Heusler alloys Rh2ZrX (X = Al, Ga, In, Si, Ge, Sn) have been studied using Quantum Espresso software package based on density functional theory. Calculations have been done by GGA and GGA+U methods. The investigations on the structural properties of the alloys showed that the Rh2ZrSi alloy had the most stable structure (Ecoh = − 1.807 eV) among the six compounds reviewed. The results of GGA calculation on electronic properties of Rh2ZrX alloys show that while the Rh2ZrX (X = Al, Ga, In) alloys had metallic nature due to overlapping between conduction and valance band at Fermi level for both spin directions, the Rh2ZrX (X = Si, Ge, Sn) alloys had half-metal characteristic. Also, Rh2ZrSi and Rh2ZrGe alloys had 100% spin polarization. By studying the magnetic properties, it was found that the Rh2ZrAl and Rh2ZrSi alloys were antiferromagnetic, while the Rh2ZrGa, Rh2ZrIn, Rh2ZrGe, and Rh2ZrSn alloys were ferromagnetic materials. Also, the total spin magnetic moment of alloys was found in accordance with the Slater-Pauling rule. The results obtained using GGA+U calculation are slightly different from the results of GGA calculation. [ABSTRACT FROM AUTHOR]

The concentration dependence of the phase stability, half-metallicity, thermal and magnetic properties of Fe2MnxNi1−xSi (0 ≤ x ≤ 1) Heusler alloys in two structures, Cu2MnAl (Fm3m) and Hg2TiCu (F43m), were investigated at the ab initio level using density functional theory. The exchange-correlation term was assessed using local spin density (LSDA) and generalized gradient approximation (GGA) along with Hubbard-U (U) corrections. Spin-polarized electronic band structure calculations for Fe2MnxNi1−xSi (0 ≤ x ≤ 1) alloys in their Cu2MnAl- and Hg2TiCu-structure have been carried out. These results indicate that the Hg2CuTi-type structure is more stable than the Cu2MnAl-type structure with increasing Mn content, from x = 0 to 0.25 using LSDA. No significant differences were observed using LSDA + U over GGA. The full Heusler compounds Fe2MnxNi1−xSi (0 ≤ x ≤ 1) are half metals in the Cu2MnAl-type structure for x = 0.75 and x = 1, and behave like a metal in the CuHg2Ti-type. The minority bands exhibit a band gap of about 0.11 (0.56) eV for Fe2Mn0.75Ni0.25Si using GGA (LSDA + U). Using the GGA scheme, the obtained band energy was smaller than that obtained by using the LSDA + U approach. These results clearly show that the lattice parameter, bulk modulus and total magnetic moment vary quadratically with Mn doping. The main contribution to the total magnetic moment comes from Mn or Fe atoms in B sites in both types of structures. The total magnetic moment of Fe2MnxNi1−xSi (0 ≤ x ≤ 1) alloys is typically in the range of 2-3 μB in the Cu2MnAl-Type and 3-4 μB in Hg2TiCu-Type per formula unit and consists of an average of 2 μB per Mn atom and less than 1 μB per Fe atom in the Cu2MnAl-Type, and an average of 2 μB per Mn atom and around 1 μB per Fe atom in the B site Hg2TiCu-Type. Using the quasi-harmonic Debye model, the concentration and temperature effects on the unit cell volume, thermal expansion coefficient, bulk modulus, the Debye temperature and heat capacity, for Fe2MnxNi1−xSi (0 ≤ x ≤ 1) Heusler alloys are investigated and analysed. [ABSTRACT FROM AUTHOR]

We analyzed the electronic and magnetic properties of new Heusler alloys Zr2NiZ (Z = Ga, In, B) with Hg2CuTi type structures based on first principles calculations. All compounds exhibit a stable half-metallic properties with band gaps in the spin-minority state 0.48 eV, 0.54 eV, and 0.62 eV, for Zr2NiZ (Z = Ga, In, B), respectively, with spin polarization equal to 100%. The calculated magnetic moment of these compounds was found to equal 3 μB per formula unit values, which all follow the Slater-Pauling rule (SP) of Mt = Zt − 18. The Zr2NiZ (Z = Ga, In, B) compounds showed half-metallic properties with a total spin polarization equal to 100% over a wide range of values of the lattice constant, and this makes these inverse Heusler alloys of maximum benefit in a wide implementations of spintronic systems. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, and optical properties of Mn-based Heusler Mn2ZrGa1−xGex (x = 0, 0.25, 0.5, 0.75, and 1) alloys are calculated by first-principles full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. It is found that Mn2ZrGa1−xGex alloys are half-metallic ferrimagnetic and their magnetic moments are in good agreement with the Slater-Pauling relationship. The calculations reveal that all alloys have a pseudo-gap in the majority-spin channel except for x = 0.75 and x = 1 which have a real gap in the majority-spin channel. The spin polarization is quite large for whole series, and it reaches to a value of 100% for x = 0.75 and x = 1. Our calculated results clearly show that with the Ge substitution, the lattice parameter linearly decreases while the bulk modulus increases. Moreover, the calculated formation energies confirm that these alloys are stable chemically. The optical properties, including the real and imaginary parts of the dielectric function, reflectivity, and absorption spectra, were also investigated. The results show that the dominant behavior, at energy below 1 eV, is due to interactions of free electrons in the system. The increment of Ge concentration leads to an increase in the plasma frequency of metallic spin channel. [ABSTRACT FROM AUTHOR]

The perpendicular magnetization of CoFeAl (CFA) full-Heusler alloy films was achieved by intentional insertion of metal layer Pt into CoFeAl thin film to induce the interfacial perpendicular magnetic anisotropy (PMA). Experimental results indicate that 0.8 nm Pt insertion can greatly improve the ratio of H(out-of-plane)/H(in-plane), indicating the generation of PMA in the Pt inserted CoFeAl thin film. At the same time, the effective damping constant of the CoFeAl film with 0.8 nm Pt insertion layer is 0.0007, which is low enough for spintronic application. Theoretically, based on the first-principles, total energy calculations also prove that the 0.8 nm Pt insertion into CoFeAl film can generate the PMA and agrees with the experimental results very well. This work reveals that 0.8 nm Pt layer insertion in CoFeAl film might pave a way towards possessing both strong PMA and 100% theoretical spin polarization in Heusler alloy films. [ABSTRACT FROM AUTHOR]

First-principles calculations within full-potential linear-augmented plane-wave method using the generalized gradient approximation were carried out for the electronic and magnetic properties of the CoCrGaSi Heusler alloys. The electronic structure calculations show a conservation of the minority spin gap supporting the half-metallic character of the CoCrGaSi alloys. The substitution of Ga by Si results in linear increasing of total magnetic moment as silicon concentration increases following the Slater-Pauling rule that is in agreement with experimental data. [ABSTRACT FROM AUTHOR]

First-principles density functional theory (DFT) calculations with the generalized gradient approximation (GGA) have been performed to investigate electronic band structures and magnetic and half-metallic characteristic of TiCoAlSn ( x = 0, 0.25, 0.50, 0.75, 1). The optimized equilibrium lattice constants were found to be equal to 6.08 and 6.37 Å for TiCoAl and TiCoSn, respectively. These ternary Heusler compounds are found to be a complete half-metal with a total magnetic moment of 2 and 3 μ , respectively, which is in good compliance with the Slater-Pauling rule, M = Z − 18. The spin-polarized band structures and density of states (DOS) of the TiCoAlSn (0.25, 0.50, and 0.75) Heusler alloys confirm that they are half-metal due to the presence of the energy gap in the minority spin. Consequently, TiCoAlSn ( x = 0, 0.25, 0.50, 0.75, 1) alloys are predicted to be a promising candidate for the practical applications in spintronic devices. [ABSTRACT FROM AUTHOR]

A first-principles study on the electronic structure and magnetic properties of the RuZrSb Heusler compound has been performed by using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It is found that the AlCuMn-type structure exhibits half-metallic ferrimagnetism and is preferable energywise than the CuHgTi-type structure. The total spin magnetic moment is based on mainly the Ru atoms and obeys the Slater-Pauling rule. The calculated total magnetic moment of RuZrSb is −1.0 μ at the equilibrium lattice constant 6.497 Å for the AlCuMn-type structure. The spin-down electrons are metallic, but the spin-up bands are semiconductor with a gap of 0.388 eV, and the spin-flip gap is 0.313 eV. The AlCuMn-type RuZrSb Heusler compound keeps a 100 % of spin polarization for lattice constants ranging between 6.40 and 6.53 Å. The Curie temperature is estimated to be 322.7 K in the mean field approximation (MFA). [ABSTRACT FROM AUTHOR]

The electronic structure of the ground and low-energy excited states of the CoFeSi Heusler alloy is investigated by the methods of X-ray absorption spectroscopy (XAS) and resonant X-ray photoelectron spectroscopy (RXPS). The orbital and spin magnetic moments of the iron and cobalt atoms are determined in a 0.05 T magnetic field. A comparative analysis is given of two amplifier channels of the valence band photoemission at the resonant excitation of the 2 p level: elastic and Auger electron emission. A decrease in the magnetic moment of the atom leads to a qualitative change in the resonant photoemission spectrum. The valence electron shake-up at a sudden appearance of a 2 p core photohole on the iron atoms leads to multiple formations of low-energy electron-hole pairs and gives rise to continuous losses in the XPS and XAS spectra. Shake-up in the cobalt atoms with great probability gives rise to one electron-hole pair with an energy of 4 eV, which is manifested as a satellite band in the above mentioned spectra. The mentioned feautures are closely related to semimetal ferromagnetism. [ABSTRACT FROM AUTHOR]

Ultraviolet photoemission spectroscopy (UPS) is a powerful tool to study the electronic spin and symmetry features at both surfaces and interfaces to ultrathin top layers. However, the very low mean free path of the photoelectrons usually prevents a direct access to the properties of buried interfaces. The latter are of particular interest since they crucially influence the performance of spintronic devices like magnetic tunnel junctions (MTJs). Here, we introduce spin-resolved extremely low energy photoemission spectroscopy (ELEPS) to provide a powerful way for overcoming this limitation. We apply ELEPS to the interface formed between the half-metallic Heusler compound Co2MnSi and the insulator MgO, prepared as in state-of-the-art Co2MnSi/MgO-based MTJs. The high accordance between the spintronic fingerprint of the free Co2MnSi surface and the Co2MnSi/MgO interface buried below up to 4 nm MgO provides clear evidence for the high interface sensitivity of ELEPS to buried interfaces. Although the absolute values of the interface spin polarization are well below 100%, the now accessible spin- and symmetry-resolved wave functions are in line with the predicted existence of non-collinear spin moments at the Co2MnSi/MgO interface, one of the mechanisms evoked to explain the controversially discussed performance loss of Heusler-based MTJs at room temperature. [ABSTRACT FROM AUTHOR]