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In this work, crystal structure, ferromagnetic martensitic transition, and magnetocaloric effect were investigated for Ni35Co15-xVxMn35Ti15 (x = 1, 2, 3) all-d-metal Heusler alloy ribbons. All three samples crystalize pure B2 cubic phase in austenite at room temperature. With increasing V content, the appearance of thermal hysteresis of thermomagnetic curves, together with the negative values of Arrott plots, proves the nature of first-order transition. And normal/reverse martensitic transition temperature (Tt/Tt') monotonously decreases from 236 (248) K (x = 1) to 82 (110) K (x = 3) and the Curie temperature in austenite (TCA) also decreases. Obvious magnetic-field-induced martensitic transition can also be seen with external magnetic field. Maximum magnetic entropy change values are 17.2, 18.7, 9.6 J/kgK with the magnetic field change of 50 kOe, respectively. The refrigerant capacity (RC) and relative cooling power (RCP), as two important parameters to evaluate the refrigeration performance, can reach 194.7 (240.8), 244.3 (300.0), 162.4 (201.6) J/kg with the magnetic field change of 50 kOe, respectively. [ABSTRACT FROM AUTHOR]

Co2MnAl Heusler alloy nanoparticle was synthesized by a facile solid-state reaction method. The structural, morphological, thermal, thermoelectrical, and magnetic properties of Co2MnAl full Heusler alloy have been investigated. The X-ray diffraction data indicates the alloy particles are polycrystalline in nature with a cubic crystal structure. The prepared alloy was thermally stable up to 705 °C, and it is confirmed through thermogravimetric analysis and differential thermal analysis. The temperature-dependent Seebeck coefficient and Hall measurement exhibit the negative carrier concentration; it shows the prepared alloy was an n-type semiconducting nature. The vibrating sample magnetometer data indicated that the alloy particle exhibits soft ferromagnetic nature with low coercivity and a high Curie temperature of 736 K. The Co2MnAl full Heusler alloy will be suitable for spintronics device applications, as it shows high magnetic moment with low coercivity. These results unambiguously indicate that it possesses great advantage for implementation into giant magnetoresistance or tunneling magnetoresistance for next-generation spintronics device application. [ABSTRACT FROM AUTHOR]

In this paper, the structural, electronic, magnetic, and elastic properties of Full‐Heusler alloy Ru2VSi are studied using density functional theory (DFT) by implementing Hubbard correction parameter (U). The calculations are performed using Generalized Gradient Approximation (GGA) with and without implementation of U and the results are compared. With GGA only, the compound shows a metallic behavior with the overlapping of bands in both the up and down spin states and exhibits a non‐integral magnetic moment. With the incorporation of U, the alloy shows a half‐metallic behavior with a finite indirect band‐gap of 0.51 eV in the spin‐down state and a metallic character in the spin‐up state. It also shows an integral magnetic moment of 1.00 μB, in good agreement with the Slater‐Pauling Rule for half‐metallicity in Full‐Heusler alloys. The elastic properties indicate toward the stability of this compound against external stresses and deformations. The observed properties make this compound a suitable material for applications based on spintronic devices. [ABSTRACT FROM AUTHOR]

The structural, magnetic, electronic, thermodynamic, optical and thermoelectric properties of the Heusler Co2Fe1−xTixGa are investigated using the full potential linearized augmented plane-wave method within density functional theory. For exchange correlation potential, we have used GGA and GGA + U approximations. Our investigation on the influence of transition metals elements doping on lattice constant, bulk modulus and band gap for quaternary alloys shows a linear dependence on alloy composition with a small deviation. The calculated lattice parameter showed in good agreement with the experimental data, the spin magnetic moments is found to be in good agreement with Slater-Pauling rule and in their equilibrium L21 structure, all concentrations are half-metallic using GGA + U scheme. Moreover, the thermodynamic effects have been investigated such as the pressure and temperature effects on the structural parameters. The optical parameters as well as the thermoelectric properties of the Co2Fe1−xTixGa in the temperature range of 300–900 K have been studied. [ABSTRACT FROM AUTHOR]

The structural, electrical, magnetic, mechanical, and thermodynamic properties of some novel half-Heusler alloys QCrAs(Q=Hf, Ti and Zr) are investigated using first principles calculations. The results show that the three half Heusler alloys are half metals and they can find application in spintronics industries. They possess magnetic moment of 3μB. The mechanical properties shows that they are mechanically stable. The B/G ratio of the three half-Heusler alloys show that they are ductile in nature and the Poisson's ratio reveal that the plasticity of TiCrAs and ZrCrAs are higher than that of HfCrAs. The Debye temperature and average sound velocity of ZrCrAs is observed to be higher than the other two alloys. This implies that the thermal conductivity of ZrCrAs is the highest. [ABSTRACT FROM AUTHOR]

In the current study, we concentrated on the influence of annealing on the magnetic behavior of Co2MnSi-based Heusler microwires. We set the annealing temperature at 1023 K for 2 h, as the sample did not show any significant changes in the magnetic properties at lower temperatures, while annealing at temperatures above 1023 K damages the glass coating. Strong in-plane magnetocrystalline anisotropy parallel to the microwire axis was evident in the magnetic behavior at room temperature for as-prepared and annealed samples. The coercivity of the annealed sample was four times higher than that of the as-prepared sample across a wide range of measuring temperatures. Both annealed and as-prepared samples exhibit quite stable coercivity behavior with temperature, which may have interesting applications. The an nealed sample did not exhibit magnetic saturation for M-H loops measured below 50 K. Sharp irreversible magnetic behavior has been detected for annealed samples at a blocking temperature of 220 K; at the same time, the blocking temperature for the as-prepared sample was 150 K. The strong internal mechanical stress induced during the fabrication of Co2MnSi microwires in addition to the internal stress relaxation caused by the annealing induced the onset of magnetic phases resulting in unusual and irreversible magnetic behavior. [ABSTRACT FROM AUTHOR]

The effect of atomic configurations on the magnetic and structural properties of Fe2NiZ (Z = Al, Ga, In, Sn) Heusler alloys has been studied within the density functional theory. The competition between five structural motifs of the cubic phase due to permutations of Fe and Ni atoms is discussed. A new structure of the cubic phase with layer-by-layer atomic ordering of Fe and Ni atoms in the ground state is predicted. In this structural modification, the considered compounds have high magnetocrystalline anisotropy values that several times exceed the values for the FeNi alloy with tetragonal symmetry. [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]

From multicomponent high-entropy alloys (AlCoCrFeNi) through ternary alloys (CrFeNi) to binary (NiCr) alloys, Cr doping plays a critical role in altering the magnetocaloric properties of the resultant alloys. Magnetocaloric effect (MCE) of Ni100−xCrx (x = 5, 10, 15 at.%) nanogranular thin films were investigated by varying Cr concentration, which demonstrate near room-temperature magnetic entropy change (− ΔSM = 0.08 J/kg K) and relative cooling power (RCP = 25 J/kg) at 10 at.% Cr. The MCE properties are well predicted using a phenomenological model based on magnetization as a function of temperature, and they correlate well with experimentally measured magnetic isotherms. [ABSTRACT FROM AUTHOR]

The phase stability and magnetocrystalline anisotropy (MCA) of tetragonal Mn(Al1−xGax) with the L10-type structure (P4/mmm) has been studied using first-principles density functional calculations. The calculated decomposition energy indicates that partial replacement of Al by Ga suppresses the formation of Mn5(Al,Ga)8 and enhances the thermal stability of the L10 phase while the total magnetic moment per formula unit (f.u.) remains almost unchanged. The site- and atomic-resolved MCA calculations show that the MCA energy (MAE) comes mainly from the Mn atoms, and the total MAE increases from 0.25 meV/f.u. (x = 0) to 0.34 meV/f.u (x = 1). Spin resolved MCA and band structure calculations indicate that the high MCA is mainly due to spin flipping behavior near Fermi level. The derived effective magnetic anisotropy field increases from 37 kOe (x = 0) to 46 kOe (x = 1), in agreement with experiments. Doping with Ga improves the thermal stability of the L10 structure and enhances the magnetic anisotropy field, which facilitates developing high coercivity Mn-Al magnets. [ABSTRACT FROM AUTHOR]

Anomalous and topological Hall effect (THE) are the fascinating electronic transport properties in condensed matter physics and received tremendous interest in the field of spintronics. Here, we report the intrinsic anomalous Hall conductivity (AHC) and THE in the bulk Ni2MnGa magnetic shape memory alloy. The magnetization measurement reveals the premartensite, martensite and magnetic phase transitions. A detailed analysis of AHC reveals that the intrinsic Berry phase mechanism dominates over skew scattering and side jump in all the structural phases of Ni2MnGa. Further, an additional contribution in the Hall resistivity is observed as THE. The magnitude of the THE and its temperature independent behavior indicates that the THE arises due to the real space Berry curvature induced by topologically protected magnetic skyrmion textures in the martensite and premartensite phases of Ni2MnGa. The larger magnetic field is required to vanish the topological Hall resistivity in the martensite phase in comparison to the premartensite phase, which manifests the more stable skyrmion textures in the martensite phase. The present findings open a new direction in the field of functional materials, which hosts skyrmion, exhibits anomalous transport and magnetic shape memory effect. [ABSTRACT FROM AUTHOR]

Ni, Co, Mn, and Al elemental powders have been ball milled in a planetary mill for various periods, up to 32 h. The obtained powder was characterized with XRD, SEM-EDS, DSC, high-temperature-XRD, and VSM techniques to study morphology, composition, thermal transitions, structural and magnetic changes occurring at high temperatures. At the end of the milling process, a particle mixture consisting of agglomerated grains with a rounded shape and an average size of about 60 µm was formed. XRD patterns of the as-milled powders revealed the presence of a nanocrystalline solid solution mixture with (L10) and (B2) structures. HT-In-situ XRD characterizations confirmed the complete formation of the B2 ordered structure from 573 K. The austenitic Heusler phase B2 remains stable during one hour of isothermal holding and its proportions increase between 648 and 773 K. Under the heating effect, crystallites size grows up greatly with increasing holding temperature, nevertheless the micro-strains decrease sharply from 0.98% at room temperature to 0.31% at 773 K. Magnetic features of the milled alloy enhance further during the heating process, making it magnetically soft with the most intriguing values of Ms, Mr, and Hc between 648 and 773 K. This is owing to the complete development of the homogeneous and ordered Heusler B2 phase and the significant increase in crystallite size with the relaxation of residual stresses resulting from the direct effects of temperature. [ABSTRACT FROM AUTHOR]

This paper presents electronic spectrum calculations and a study of the optical properties of the binary compounds Mn70Al30 and Mn80Al20 with the β-Mn structure. The energy dependences of the calculated density of states, with high values at the Fermi level, are determined by broad bands formed by manganese 3d states. The calculated electronic structures are used to analyze measured optical conductivity spectra of the alloys in the quantum light absorption range. From their optical properties in the infrared spectral region, we evaluate a number of characteristics of conduction electrons. [ABSTRACT FROM AUTHOR]

Based on the analysis of the magnetic state of austenite, changes in thermodynamics and kinetics of the martensitic transformation in carbon steel have been determined. Depending on the strength of the external magnetic field, the dimensions of the magnetic inhomogeneity regions in austenite were calculated. It was shown that with an increase in the field strength, the size and the quantity of such regions increase. Changes in free energy of austenite, caused by the appearance of ferromagnetic order fluctuations, have been determined. The free energy of formation of one ferromagnetic cluster in austenite was estimated. Changes in the energy of formation and diameter of the critical martensite nucleus were analyzed depending on the strength of the external magnetic field. Data about an increase in the volumetric martensite transformation rate under the exposure to a magnetic field were obtained. [ABSTRACT FROM AUTHOR]

The electronic structure and thermoelectric (TE) properties of Ir (iridium)‐based Heusler alloys (HAs), Ir2MnX (X = B, Al, Ga, In), are examined by density functional theory (DFT). To the best of the authors' knowledge, there are no findings on the TE properties of these Ir‐based Heusler compounds. All of the Ir2MnX (X = B, Al, Ga, In) alloys are stabilized to ferromagnetic ordering. The calculated equilibrium lattice constants vary from other results by 0.2%. This study is focused on the half‐metallic behavior of the alloys based on their electronic structure and finite magnetic moment, which defines their viability for spintronic applications and TE device fabrication. The computed spin magnetic moments follow the Slater–Pauling rule. Among the four investigated compounds, Ir2MnB is dynamically unstable. The transport property is explored using the semiclassical Boltzmann transport theory for structurally and dynamically stable alloys Ir2MnX (X = Al, Ga, In). At 800 K, the maximum power factor of the alloys is achieved at a hole concentration of −1.25 × 1011 W m−1 K−2 s−1, indicating that these are promising TE application alloys. [ABSTRACT FROM AUTHOR]

The classical Bardeen–Cooper–Schrieffer and Eliashberg theories of the electron–phonon-mediated superconductivity are based on the Migdal theorem, which is an assumption that the energy of charge carriers, k B T F , significantly exceeds the phononic energy, ℏ ω D , of the crystalline lattice. This assumption, which is also known as adiabatic approximation, implies that the superconductor exhibits fast charge carriers and slow phonons. This picture is valid for pure metals and metallic alloys because these superconductors exhibit ℏ ω D k B T F < 0.01 . However, for n-type-doped semiconducting SrTiO3, this adiabatic approximation is not valid, because this material exhibits ℏ ω D k B T F ≅ 50 . There is a growing number of newly discovered superconductors which are also beyond the adiabatic approximation. Here, leaving aside pure theoretical aspects of nonadiabatic superconductors, we classified major classes of superconductors (including, elements, A-15 and Heusler alloys, Laves phases, intermetallics, noncentrosymmetric compounds, cuprates, pnictides, highly-compressed hydrides, and two-dimensional superconductors) by the strength of nonadiabaticity (which we defined by the ratio of the Debye temperature to the Fermi temperature, T θ T F ). We found that the majority of analyzed superconductors fall into the 0.025 ≤ T θ T F ≤ 0.4 band. Based on the analysis, we proposed the classification scheme for the strength of nonadiabatic effects in superconductors and discussed how this classification is linked with other known empirical taxonomies in superconductivity. [ABSTRACT FROM AUTHOR]

Both L21 and XA type phases ordering of Ti2FeGe compound were investigated based on density functional theory. The structural, magnetic, band structure, density of states, possibility of martensitic transformation, elastic, thermoelectric and optical properties were studied. From the calculated total energy, we noted that L21 type in ferromagnetic state is more stable phase using GGA+U approach. The computed elastic constants of considered compound show that L21 type is ductile, anisotropic and mechanically stable, while the XA phase ordering of Ti2FeGe is not mechanically stable. The (DOS) and band structure of L21 type structure of Ti2FeGe alloy show metallic character in both spin up and spin down directions, while the XA type structure exhibits half-metallic character. Based on quasi-harmonic Debye model applied in the Gibbs program, the lattice vibrational, the bulk modulus, the Debye temperature, the heat capacity, the entropy, the coefficient of thermal expansion and the Grüneisen parameter have also been estimated. The thermoelectric properties of two phases are examined and discussed through consideration of transport coefficients. The optical properties are systematically studied by computing the optical parameters. The obtained results will bring perspective for designing theoretical predictions and experimental studies intended to serve as a reference for future studies on optoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]

Using the full-potential linearized augmented plane wave plus local orbital method based on spinpolarized density functional theory, we investigate the parameters of the structure, the electronic, magnetic, and thermodynamic properties of cubic zinc-blende Cd0.75Cr0.25Se and Zn0.75Cr0.25S ordered ferromagnetic materials. We adopt the Perdew–Burke–Ernzerhof generalized gradient approximation and the modified Becke–Johnson exchange potential for the exchange-correlation energy and potential. Furthermore, the effect of high pressure on the normalized unit cell volume, bulk modulus, and Grüneisen parameter for both CdSe and ZnS binary compounds as well as for Cd0.75Cr0.25Se and Zn0.75Cr0.25S partially substituted materials was also predicted. The results indicate that both these materials are stabilized in the ferromagnetic phase. Using the modified Becke–Johnson approach and Perdew–Burke–Ernzerhof generalized gradient approximation, our calculations also demonstrate that both Cd0.75Cr0.25Se and Zn0.75Cr0.25S alloys are semiconductors with the magnetic moment of 4 µB per formula unit. Furthermore, the calculations of the s–d exchange constant and p–d exchange constant clearly indicate the magnetic nature of these compounds. Finally, in order to gain further information, basic thermodynamic properties such as heat capacity, thermal expansion coefficient, and entropy have been explored using the quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]

Co-based Heusler alloys have high Curie temperatures and high spin polarization ratio, showing potential application prospects in spintronics devices. This paper investigates the structural, magnetic, mechanical, dynamic stability and electronic properties of CoFeXSn (X = Ti, V, Cr) alloys by first-principles calculations. The results show that the CoFeXSn (X = Ti, V, Cr) alloys all crystallize in a LiMgPbSn-type structure and follow the preferential occupation rule. The magnetic coupling between Co-Ti/V and Co-Cr alloys are different, but both are consistent with Slater-Pauling behavior. The CoFeTiSn and CoFeVSn alloys are mechanically and dynamically stable, while the CoFeCrSn alloy has a significant imaginary frequency in the phonon dispersion curves. The electronic structure analysis shows that these alloys have energy gaps in one of the spin directions, indicating that these alloys have properties close to those of half-metal materials. [ABSTRACT FROM AUTHOR]

Chromium-rich Cr-V alloys exhibit three phases. The paramagnetic phase (P) above Néel temperature (TN), a transverse polarization spin-density-wave (SDW) phase (AF1) below TN and above the spin–flip temperature (TSF), when the longitudinal polarization SDW phase (AF2) is formed. In the paramagnetic phase, Cr exhibit a Pauli susceptibility with weak temperature dependence. Otherwise, the introduction of small amounts of V in Cr not only decreases TN continuously, but also induces a Curie-Weiss behavior (CW) that we associate with local magnetic moments. This behavior is limited up to 0.67%V and magnetic fields of 15 kOe and was also observed for different Cr alloys. The origin of local magnetic moments has been associated with the establishment of local spin-density waves (LSDW) around V impurities. In this work, we presented an investigation of the effects of local magnetic moments in antiferromagnetic phases in Cr-V alloys. The magnetic susceptibility measurements around the spin–flip transition suggest that the local-SDW induces the strong magnetic anisotropy in the long-range order of the spin-density wave as it is revealed in the thermomagnetic results. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the structural, electronic, magnetic, elastic, thermoelectric, and thermal properties of Co2FeGa1−xSix with 0 ≤ x ≤ 1 through the first-principles density functional calculations. We have determined the structural parameters using GGA and GGA + U approaches. In regard to the electronic and magnetic properties, we used GGA, GGA + U, and mBJ-GGA schemes. We have determined the lattice parameter, the bulk modulus, and the total magnetic moment at the equilibrium ground state. Subsequently, we have obtained the results comparable with the experimental data. The electronic band structures and density of states of our compounds with x = 0.00, 0.25, and 0.50 shows a half-metallic character, whereas the systems with the compositions x = 0.75 and 1 exhibit the metallic behavior. Furthermore, the magnetic moment total obtained by two approximations GGA + U and mBJ-GGA is greater than that obtained by GGA. Also, we have analyzed the thermodynamic properties through the quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]

Direct and indirect measurements of the magnetocaloric effect in La0.7Pb0.3-xBaxMnO3 (x = 0.05, 0.10, and 0.15) manganite were reported. The effect of Pb substitution with Ba on the structural, magnetic, and magnetocaloric properties of these compounds was investigated. The X-ray analysis reveals a structural transition upon doping. The rhombohedral structure of x = 0.05 is transformed into a mixture of cubic and rhombohedral phases for both samples x = 0.10 and x = 0.15. For all the samples, magnetic versus temperature analysis shows a transition from a paramagnetic (PM) to a ferromagnetic state (FM). The zero-field heat capacity measurement was also performed. The magnetocaloric efficiency was determined from adiabatic temperature and isothermal magnetization curves using Maxwell relation. It is found that the sample with the composition x = 0.10 exhibits the highest value of ΔTad and ΔSm which were found to be 1.75 K and 1.445 Jkg−1 K−1 at 3 T respectively. The corresponding relative cooling power (RCP) was around 145.5 Jkg−1. The phenomenological construction of the universal curves and the Banerjee criterion revealed a second-order phase transition for all samples. [ABSTRACT FROM AUTHOR]

The influence of potassium (K) doping on the magnetic and magnetocaloric effect of the perovskite-type manganese oxides La0.6Sr0.4−xKxMnO3 in low magnetic field has been investigated. Our work shows that the maximum magnetization and the Curie temperature of La0.6Sr0.4−xKxMnO3 (x = 0.10, 0.15, 0.20) decrease with increasing K content. Using Hamad's phenomenological model, we have estimated the important magnetocaloric properties such as the magnetic entropy change and the relative cooling power. Tunable Curie temperature and considerable magnetocaloric properties of these manganese oxides are advantageous for applications in sub-room and near-room temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The critical behavior for the second-order ferromagnetic paramagnetic phase transition Ni50Mn29Ga20.8Tb0.2 alloy is studied. The values of the critical exponents were found to be γ = 1.05 , β = 0.45 and are close to the ones described by the mean-field model. Using the Arrott–Noakes equation of state with these γ and β values, the Curie temperature was successfully calculated. The isothermal magnetization M and magnetic entropy change - Δ S M curves were simulated using the Arrott–Noakes equation, the Landau theory and a mean field model. [ABSTRACT FROM AUTHOR]

Heusler alloy research has increased considerably in recent years. This is mostly due to their strong desire to develop future smart device applications. However, many limiting variables remain for researchers to overcome in order to enhance their functional properties. The poor mechanical properties of these alloys restrict their use as solid-state cooling materials in magnetic refrigeration devices. A promising strategy, resulting in novel compounds with better mechanical properties and substantial magnetocaloric effects, is favoring the d–d hybridization with transition-metal elements to replace p–d hybridization. The term given to these materials is "all-d-metal". In light of recent experimental results of the magnetocaloric effect and the increased mechanical characteristics in these alloys (with complex crystallographic behavior due to off-stoichiometry and disorder), a review of this advanced functional behavior is offered. Moreover, the impact of the substitution of transition metal for the p-group to increase mechanical ductility and considerable magnetocaloric effects has also been addressed. These Heusler alloys are a potential new class of materials for technological applications because of their optimum functional behavior. Finally, we highlighted the potential challenges and unsolved issues in order to guide future studies on this topic. [ABSTRACT FROM AUTHOR]

Ni-Mn-based quinary Heusler alloys have seldom been investigated with respect to their martensitic transformation and mechanical properties for near room temperature transformation. In the current work, we identified and investigated martensitic transformation near room temperature, and the martensitic properties of Ni-Mn-Sn-Fe-In-based quinary Heusler alloys. Alloys prepared in an argon-rich vacuum arc melting furnace. During X-ray diffraction (XRD) analysis, it was identified that the L21 cubic structure austenite phase of the alloy transforms into L10 orthorhombic martensite phase in the case of alloys with greater Fe substitution. The martensitic transformation zone of the alloy is also shifted to the near-room-temperature range of 15–28 °C by changing the stoichiometry of the alloy composition. Magnetic measurements like field heating (FH), field cooling (FC) and zero field cooling (ZFC) indicate the presence of a dual magnetic phase in the alloy, while magnetic susceptibility testing also helped to establish claims regarding the magnetic measurement results. [ABSTRACT FROM AUTHOR]

The magnetic and electrical characteristics of Ni-Mn quinary Heusler alloys are studied in the current work. The results concern the materials' magnetic and electrical behavior. The physical property measurement system (PPMS) and superconducting quantum interference device (SQUID) were used at various magnetization levels to determine the results. The addition of Fe helps to form the alloy into a smart memory alloy with magnetocrystalline anisotropy, twin border mobility, and varied magnetic and martensite transition temperature characteristics. Character changes in the superparamagnetic (SPM) and paramagnetic (PM) alloys occur between 26 and 34 °C. The curves are supported by the alloy's martensitic transition temperature change. A large refrigeration capacity is identified in the alloy. These properties are an indication of the alloys' application prospects. Entropy change helps to detect the inverse magnetocaloric effect in the alloy, whereas adiabatic temperature change helps identify the origin and validity of reverse magnetic properties. The transition temperature changes occur when austenite's sigma is larger than that of martensite, and as the magnetic field increases, the temperature declines. Isothermal magnetization curves, a large (MR)/B value at low and high magnetic fields, and temperatures near the transformation point suggest that small-crystal Heusler alloys have tremendous promise for low and high magnetic field magnetoresistance applications. [ABSTRACT FROM AUTHOR]

Thin films of ferromagnetic (Fe70Ni30)96Mo4 were grown via molecular beam epitaxy. Their magnetic properties and magnetocaloric effects were investigated. X-ray diffraction and vibrating sample magnetometry measurements confirmed the crystalline ferromagnetic (Fe70Ni30)96Mo4 phase, with a Curie point near room temperature. To determine the suitability of this material for magnetocaloric applications, we observed a large magnetic entropy change with a large temperature span as well as high relative cooling power near Curie temperature comparable to rare-earth-based materials operating near room temperature. [ABSTRACT FROM AUTHOR]

Article highlights The arc-melting method is used to synthesize new Fe2V1-xMnxGe cubic Heusler alloys. Both increment of Mn and decrement V in the structure, reveal phase transition from hexagonal DO19 to cubic L21 form. The M-H graphs for Fe2V1-xMnxGe alloys measured at 5 K present almost no coercive fields and easy magnetization.

Directional designing a catalyst with high direct deoxygenation selectivity of Phenols during hydrodeoxygenation (HDO), remains a formidable challenge in cost-effectively converting biomass to bio-fuel and chemicals. Herein, we evaluated for the first time the catalytic performance of Heusler alloy surfaces for HDO process of m-cresol at the atomic scale. The direct deoxygenation (DDO) route of m-cresol on the Co 2 FeGa (110) surface at 573.15 K exhibited relatively low kinetic (1.20 eV) and thermodynamic (−0.04 eV) barriers, leading to high selectivity (near 100 %) for toluene production. The degree of rate control (DRC) analysis revealed that direct dehydroxylation constituted the rate-limiting elementary reaction. Additionally, by tailoring the Ga and Ge ratio on the Co 2 FeGa 1-x Ge x (110) surface, an almost linear relationship (R2 = 0.95) was discovered between activation energy of C-OH and the d -band center energy of the Fe element in the unit cell. Both the activation energy of C-OH and d-band center energy of the Fe decreased with increasing Ge/Ga substitution ratio. This research unveils for the first time the catalytic performance of Heusler alloy for the selective direct deoxygenation of m-cresol , but also suggest the possibility tuning d -band center of Heusler alloys to precisely tailor the selectivity of DDO during HDO process. [Display omitted] • The Heusler alloys Co 2 FeGa were found to exhibit exceptionally high direct deoxygenation selectivity towards phenols for the first time. • The direct dehydroxylation is the key rate-limiting step. • An approximate linear relationship (R2 = 0.95) between the kinetic barriers and the d -band center energy of the Fe element was discovered. [ABSTRACT FROM AUTHOR]

The effect of strains on electronic structures, elastic properties, magnetic properties and Curie temperature of Pd 2 FeCu are calculated by GGA + U method. The impact of strains on the magnetism of Pd 2 FeCu is evaluated. The magnetism without and with spin-orbit coupling (SOC) effect under diverse strain are examined. The results show that Pd 2 FeCu is a ferromagnetic metal with good ductility and mechanical stability. The SOC effect has a negligible impact on the atomic magnetic moment of Pd 2 FeCu. When the compressive and tensile strains are imposed, the ferromagnetic metal properties still keep, and the Curie temperature of Pd 2 FeCu is higher than room temperature. The ferromagnetism for Pd 2 FeCu is very robust with respect to the variation of the strain. And the Ruderman-Kittel-Kasuya-Yoshida (RKKY) type ferromagnetic interaction play a crucial role to determine the ferromagnetism. We expect this work could stimulate experimental study. • Pd 2 FeCu is a ferromagnetic metal with good ductility and mechanical stability. • Spin-orbit coupling effect has a negligible impact on the magnetism. • Compressive and tensile strains are imposed, the ferromagnetic metal still be kept. • The Curie temperature of Pd 2 FeCu is higher than room temperature. • RKKY interaction play a crucial role to determine the ferromagnetism. [ABSTRACT FROM AUTHOR]

The structural, mechanical, electronic, thermodynamic, and phonon characteristics of Sc 2 CdAl and Sc 2 ZnAl in L2 1 phase were the main focuses on this investigation. The density of states (DOS) and electronic band spectra signify the metallic behavior of the L2 1 phase of both materials. The impact of atomic arrangement with respect to the Wyckoff sites on the mechanical stability were additionally studied. The elastic constants of Sc 2 CdAl and Sc 2 ZnAl alloys indicated that these alloys convened Born mechanical stability criteria. Using the density functional perturbation theory's first-principle linear response method, complete phonon spectra have been acquired. Moreover, the quasi-harmonic approximation, specific heat capacity at constant volume, the internal free energy, entropy, and vibrational free energy variations of Sc 2 CdAl and Sc 2 ZnAl as full Heusler alloys have been utilized in examination the change over the temperature between 0 and 800 K. Both alloys might find application in real industrial applications. [ABSTRACT FROM AUTHOR]

The results of a study of the resistivity, thermal conductivity, thermoelectric power, and thermal expansion of a polycrystalline Ni 47 Mn 40 Sn 13 Heusler alloy as a function of temperature (80–350 K) and magnetic field (0–8 T) are presented. In addition, ab initio calculations of the structural, electronic magnetic and thermal properties of Ni-Mn-Sn alloy are performed. It is shown that the sensitivity of the magnetostructural phase transition (MSPT) to a magnetic field is Δ T /Δ H ≈2 K/T. The temperature dependence of the thermoelectric power near the temperature of the magnetostructural phase transition has a minimum, which is due to a competition between the contributions of electrons and holes to the thermoelectric power. In the region of the martensitic transition, a jump-like increase in thermal conductivity Δκ≈4.2 W/m×K was detected, which is associated with both an increase in the electronic component due to an increase in the mobility of charge carriers, and an increase in the free path of phonons as a result of narrowing of the phonon relaxation channel upon transition to a less defective austenitic phase. The ab initio calculations reproduce well a jump-like behavior in the electronic and phonons components of thermal conductivity, providing Δκ of 4.63 W/m×K for electron-doped compound. It is shown that the martensitic transformation between the austenitic and martensitic phases is accompanied by a slight change in the carrier concentration, which is about 3 %. This result confirms the experimental suggestion about the weak change in the charge carriers at the martensitic transformation. The martensite-austenite phase transition is accompanied by a sharp increase in the linear dimensions of the sample Δ l/l 0 ≈1.5×10−3. A direct relationship was found between Δρ/Δρ 0 and magnetostriction near the MSPT temperature in a magnetic field of 1.8 T. [Display omitted] • The thermoelectric power has a negative sign and a deep minimum near the temperature of magnetostructural transformation. • An increase in thermal conductivity is observed during the transition from the martensitic phase to the austenitic one. • The results of the first-principle calculations provide the preference of martensitic tetragonal phase as a ground state. • Both the austenite and martensite phases are ferrimagnetically ordered but with different spin configuration of Mn atoms. • The contributions of electrons and phonons to the jump in k tot near the MSPT are estimated at 53.2% and 46.8% respectively. [ABSTRACT FROM AUTHOR]

Entropy engineering is a promising strategy for high-performance thermoelectrics, as it enhances material stability, reduces thermal conductivity, and optimizes electronic transport by manipulating configurational entropy. This perspective highlights the design principles and recent advancements in the development of entropy-stabilized Heusler alloys (ESHAs) for thermoelectric applications. The extensive compositional space available in ESHAs provides exciting opportunities to explore entropy stabilized multicomponent alloying, potentially leading to the discovery of new compositions with enhanced thermoelectric properties. However, challenges persist in optimizing these compositions, understanding the composition – structure – properties relationships, and scaling up production. Addressing these challenges remains critical for advancing the practical application of ESHAs in thermoelectrics. [Display omitted] • Design Principles : ESHAs utilize high configurational entropy to stabilize phases. • Recent Advancements : ESHAs show improved zT values, surpassing traditional alloys. • Phase Stability : Advances enable ESHAs to maintain stability at elevated temperatures. • Current Challenges : Achieving full homogenization in multi-element compositions remains difficult. • Future Directions : Research will focus on compositional complexity and advanced characterization. [ABSTRACT FROM AUTHOR]

Intrinsic spin currents are encountered in noncentrosymmetric crystals without any external electric fields; these currents are caused by spin–orbit interaction. In this paper, various theoretical aspects of this phenomenon in bulk ferromagnets are studied by using group theory, perturbation expansion, and calculations for model and real systems. The group-theoretical analysis of the spin-current tensor shows that the absence of space-inversion symmetry is not a sufficient condition for appearance of the intrinsic spin currents. The perturbation expansion proves that in the regime of exchange splitting dominating over spin–orbit interaction, the spin polarization of the intrinsic currents is nearly perpendicular to the direction of magnetization. First-principles calculations are carried out for NiMnSb and CoMnFeSi ferromagnetic compounds, both featured by a tetrahedral crystallographic point group. The dependence of the spin-current tensor on the direction of magnetization is approximated by a simple quadratic formula containing two constants; the relative error of this approximation is found as small as a few percent for both compounds. • Intrinsic spin currents are analyzed in terms of group theory. • Spin-current tensor in noncentrosymmetric Heusler alloys is calculated. • Effect of magnetization direction on spin-current tensor is studied. • Quadratic dependence on magnetization direction is derived and tested. • Polarization of spin currents is nearly perpendicular to magnetization. [ABSTRACT FROM AUTHOR]

• The structural, magnetic, electronic and optical properties of half Heusler VXPt (X = Br, Se) alloys hae been studied. • Optimisation curves with negative formation energy show that the alloys under investigation are stable. • For VBrPt, an energy gap is present in major and minority spin carriers, while for VSePt, metallic character is seen in minority spin carriers. • An optical band gap with maximum absorption reveals that these alloys are useful for optoelectronics. High-spin polarized magnetic materials might be useful in spintronics applications. The spin-polarized magnetic, optical, electronic and structural attributes of half-Heusler VXPt (X = Br, Se) alloys were theoretically explored and calculated using the WIEN2k code. The ground states of the structures are optimized, and the bulk moduli and lattice constants are computed. The values obtained from the formation energies show their stability. For VBrPt, an energy gap is present in major and minority spin carriers, while for VSePt, major spin carriers exhibit an energy gap and metallic character is seen in minority spin carriers. The band structures are further illustrated deeply through the investigation of density of states. The electron density graphs depict the ionic bonding in both alloys. The magnetic moments are additionally assessed, and the recorded values support the magnetic characteristics of VBrPt and VSePt. The assessment of how the studied alloys react to light is determined by computing various parameters. The imaginary component and absorption coefficient anticipate substantial light absorption within the visible region. The calculated outcomes unveiled the potential of the examined alloys for applications in spintronics. [ABSTRACT FROM AUTHOR]

High optical absorption coefficient and low reflectivity confirm use in solar cell applications. Material holds great potential for thermoelectrical applications. [Display omitted] • Electronic parameters reveal semiconducting nature. • Positive values of Seebeck coefficients indicate p-type character of X 2 MnB. • High optical absorption coefficient and low reflectivity confirm use in solar cell applications. In this manuscript comprehensive first-principles calculations have been presented for Full-Heusler X 2 MnB (X = Ti, Zr) compounds. This work includes detailed observations of the structural stability, origin of the transport phenomenon, optical properties, and electronic response. Structural parameters support the previous findings by confirming structural stability in the non-magnetic phase. Ti 2 MnB (Zr 2 MnB) valence band maxima and conduction band minima have bandgaps of 0.217 (0.301) eV and 0.181 (0.209) eV for PBE-GGA (mBJ) approximations which lie between L-L symmetry points. Due to the comparative measurements of the two states, the DOS results show that the Ti 1 /Zr 1 , Ti 2 /Zr 2 Mn e g , and t 2g states mainly contribute to the valence band region for Ti 2 MnB and Zr 2 MnB alloys, confirming their ionic nature. The computation of the overall electronic parameters' reveals semiconducting nature. Thermoelectric properties have been calculated as a function of temperature in the 100–1200 K range. The positive values of Seebeck coefficients specify p-type character of X 2 MnB While at 300 K, Zr 2 MnB and Ti 2 MnB showed the highest Seebeck coefficients, measuring roughly values of 268 (µK/V) and 243 (µK/V), respectively. These values suggest that the material exhibits high thermoelectric performance. Though high optical absorption coefficient and low reflectivity in the visible and ultra violet regions, confirms use of these materials in solar cell applications. These findings suggest that material holds great potential for use in thermoelectrical applications which can support in upcoming experimental considerations. [ABSTRACT FROM AUTHOR]

In this study, the structural, electronic, magnetic, thermodynamic, and elastic attributes of ZMnAs (Z = Be, Mg) have been investigated. These Half-Heusler alloys exhibit stability in the ferromagnetic state (FM), as demonstrated by optimization-related energy release. The half-metallicity (HM) of these compounds is examined through the band structures and density of states (DOS). In addition, the crystal field and exchange energies are reported to confirm the control of electron spin. Additionally, the double exchange process and exchange constants were premeditated. In this case, ferromagnetism (FM) is caused by the quantum exchange of electrons, as evidenced by the negative pd exchange energy and the exchange constants, rather than being a result of clustering effects. The quasi-harmonic Debye model, included within the Gibbs code, was utilized to calculate the thermodynamic properties. These two compounds are mechanically stable and show ductile nature confirmed by the value of Poisson's ratio (v), Pugh's ratio (B/G), and Cauchy pressure (C P), which demonstrates the ability to withstand substantial plastic deformation before fracturing. Based on our calculations, the half-metallic (HM) nature, thermodynamic, ferromagnetic, ductile, and high inherent magnetic moment have been evaluated. These alloys are crucial in the advancement of spintronics and renewable energy systems. [ABSTRACT FROM AUTHOR]

• The pure B2 structure in all-d-metal Heusler ribbon Ni 35 Co 15 Mn 34 Ti 16 is achieved. • The values of −Δ S M reach 1.62(3.42) J kg−1 K−1 with ΔH=20(50) kOe. • The values of TEC(10 K) reach 1.64(3.44) J kg−1 K−1 with ΔH=20(50) kOe. • The values of TEC maintain in wide temperature range. The new all-d-metal Heusler alloys with good mechanical properties are candidates for magnetocaloric materials compared other famous refrigeration materials. In this work, Ni 35 Co 15 Mn 34 Ti 16 ribbon with a second-order magnetic transformation was investigated for magnetoclaoric effect. It crystalizes pure B2 structure at room temperature and undergoes a SOMT at Curie temperature in austenite (T C A = 358 K) between paramagnetic and ferromagnetic phase. A large saturation magnetization (M S) at 5 K is 166 emu/g. The maximum values of magnetic entropy change (−Δ S M) and the temperature-averaged entropy change TEC(10 K) reach 1.62(3.42) J kg−1 K−1 and 1.64 (3.44) J kg−1 K−1 with magnetic field change (ΔH) of 20(50) kOe, respectively, which are comparable to most of other all-d-metal Heusler alloys. [ABSTRACT FROM AUTHOR]

• New materials for thermoelectric and spintronic application were analyzed. • Structural properties of the materials in stable ferrimagnetic phase have been discussed. • The materials have negative magnetic moment which is very useful in the spin transport behavior. • Thermoelectric performance of the materials was analyzed and suggest that TaMnZ (Z = As, Sb and Bi) materials are suitable for thermoelectric and spintronic applications. • This research provides further ways for experimentally synthesizing the materials and fabricating them as spin-based transistortransistors, diodes, and thermoelectric generators. Half metals possess coupling behavior of metals and semiconductors with wide heat transport and spin transport properties. This research article covers the structural, mechanical, electronic, magnetic and thermoelectric properties of the half Heusler alloys TaMnZ (Z = As, Sb, Bi). The equilibrium lattice constants and corresponding ground state energies show that the studied alloys are stable in the ferrimagnetic cubic phase. The band dispersion plots suggest that the compounds TaMnAs, TaMnSb and TaMnBi are half metals with indirect band gap having the band gap energies of 1.13 eV, 1.24 eV and 1.12 eV respectively in the spin down channel. As the materials have 100 % spin polarization with an integer magnetic moment of −1 μ B , they are suitable for making spintronic devices such as spin transistors and spin-flip flops. The temperature-dependent thermoelectric properties of the alloys have been studied by classical Boltzmann theory. The materials have low lattice thermal conductivity which was confirmed by Slack's equation. The obtained thermoelectric figure of merit for p-type TaMnAs, TaMnSb and TaMnBi is 0.7, 0.6 and 0.8 respectively at 1200 K. Similarly, the figure of merit obtained for n-type TaMnAs, TaMnSb and TaMnBi is 0.6, 0.64 and 0.8 respectively at the same temperature. The favourable heat and spin transport properties of these alloys show that they are the potential characters to figure out better thermoelectric and spintronic performance. [ABSTRACT FROM AUTHOR]

We investigated the magnetic properties of the Heusler alloy NiMnSn grown on thermally oxidized Si (100) by performing magnetic hysteresis measurements using the Polar Magneto-Optical Kerr Effect (PMOKE) technique. For a thickness of 30 nm, the NiMnSn alloy demonstrates out-of-plane magnetic anisotropy. We observed clear exchange bias, which we attribute to the exchange coupling between the spin glass and ferromagnetic phases. Our study also revealed that the growth of a 1 nm thick Heusler alloy NiMnSn layer on a cobalt layer with perpendicular anisotropy enhances the perpendicular magnetic anisotropy. However, we observed an antagonistic effect with thicker Heusler layers, resulting in a loss of perpendicular anisotropy and the appearance of an exchange bias (EB). • A highly textured NiMnSn Heusler alloy was deposited by electron beam evaporation. • The polar Magneto-Optical Kerr Effect shows an out-of-plane anisotropy and room temperature exchange bias. • The NiMnSn alloy exhibits out-of-plane magnetic anisotropy for a thickness of 30 nm. • 1 nm thick Heusler alloy NiMnSn layer grown on a cobalt layer leads to an improvement in perpendicular magnetic anisotropy. [ABSTRACT FROM AUTHOR]

To determine the structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of novel quaternary Heusler alloys type ZrCoYAs (Y= Fe and Mn), we used DFT with WIEN2k. Our results showed that the ferromagnetic Y-type-III phase is more stable due to the higher negative values of their formation energy. We calculated and discussed the elastic constants C ij , which are used to calculate the mechanical properties. The Spin-polarized band structure and DOS calculations using the GGA-PBE and GGA + U approach display a metallic character. However, using the mBJ-GGA-PBE and mBJ-GGA + U approach show a half-metallic character, a semiconductor for the spin-down channel with a direct band gap of 0.61 eV with mBJ-GGA-PBE and 0.74 eV with mBJ-GGA + U for ZrCoMnAs and a direct band gap of 0.43 eV with mBJ-GGA-PBE and indirect band gap with 0.39 eV with mBJ-GGA + U for ZrCoFeAs, in contrast, the spin-up channel is metallic, with 100 % spin polarization and an integer magnetic moment of 1.00 μB for ZrCoMnAs and 2.00 μB for ZrCoFeAs, obeying the Slater-Pauling rule. The estimated Curie temperatures of ZrCoMnAs and ZrCoFeAs are 204 K using the new model, 421 K using MFA, and 385 K using the new model, 1627 K using MFA, respectively. As exchange-correlation potential, MBJ and MBJ + U provide a better description of the electronic and magnetic properties of ZrCoMnAs and ZrCoFeAs compounds. Important optical properties such as dielectric function, absorption coefficient, refractive index, optical conductivity, reflectivity, and electron energy loss function are calculated in the infrared, visible, and ultraviolet range. The static dielectric function suggests that ZrCoMnAs possesses greater polarizability. Both alloys exhibit similar behavior in the far ultraviolet region range and reach a maximum absorption in the ultraviolet range. The half-metallic character of both alloys is revealed from the reflectivity at zero frequency. The calculation of the thermoelectric properties shows positive Seebeck coefficients, indicating that these Heuslers are p-type. Furthermore, the highest power factor is observed at a temperature of 1400 K. The maximum value of ZT is ∼1.1 at 1400 K for ZrCoFeAs and ZrCoMnAs. These studies show that these alloys may have potential applications in the thermoelectric applications. • This article applied an FP-LAPW approach to determine the properties of novel quaternary Heusler alloys. • An asymmetric behavior was found about the electronic and magnetic properties using GGA, GGA+U, mBJ-GGA and mBJ-GGA+U. • The thermodynamic and mechanical stabilities of the studied compound were examined. • Important optical and thermoelectric properties are calculated. • These studies show these compounds may have potential applications in spintronics and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Defect (mainly vacancy) engineering has shown its potential for modulating the functional behavior of magnetic materials. In this work, dense Ni vacancies are introduced in Ni 45 Mn 36.5 In 13.5 Co 5 alloy and the effect of these vacancies on the magnetic properties is both theoretically and experimentally clarified. In detail, Ni vacancy with the lowest formation energy is introduced by high energy electron irradiation, which shortens the distance between adjacent Mn atoms to strengthen the interaction between them and increase the corresponding magnetic moments, leading to the d T m /d H increase from −2.89 to 6.28 KT−1. As a result, a breakthrough in the magnetocaloric performance is correspondingly achieved, i.e., the entropy change (Δ S M) increases up to an ultra-high value of 48.15 J/(kg·K), much higher than all other reported values. Moreover, the reversible magnetostrain is also improved from 80 to 200 ppm. In summary, this work provides strong guidance for optimizing the magnetic performance of Ni–Mn based Heusler alloys via vacancy modulation. • Dense V Ni formation decreases the electron localization function between the two Mn atoms. • Dense Ni vacancies are introduced in Ni 45 Mn 36.5 In 13.5 Co 5 alloy through high-energy electron irradiation. • Ultra-high Δ S M of 48.15 J/(kgK), much higher than all other reported values, is achieved. [ABSTRACT FROM AUTHOR]

In this work, all-d metal Heusler alloys Ni–Mn–Cr were predicted by first principles. Their structure, magnetism, tetragonal distortion and electronic properties were studied. The cubic groud state structures of Ni 2 MnCr and NiMnCr 2 are XA type, and that of NiMn 2 Cr is L2 1 type. All of them have magnetism. The change of their lattice constants is closely related to the covalent radius of atoms. Ni 2 MnCr has a stable tetragonal phase and may undergo martensitic transition. NiMn 2 Cr has a lower energy tetragonal phase, but is dynamically unstable. The equilibrium volumes of the two compounds expand through tetragonal distortion. NiMnCr 2 does not have a lower energy tetragonal phase. In the tetragonal distortion, the atomic magnetic moments are influnced by the interatomic distance and the magnetic moments of neighboring atoms. The origin of the tetragonal distortion and magnetic properties was discussed in terms of the electronic density of states. • Ni 2 MnCr and NiMnCr 2 have an XA-type structure, NiMn 2 Cr has an L2 1 structure, and all of them exhibit magnetism. • Ni 2 MnCr has a stable tetragonal phase and may undergo martensitic transition. • The atomic magnetic moments are influenced by the interatomic distance and the magnetic moments of neighboring atoms. • The Jahn-Teller effect triggers the tetragonal distortion. [ABSTRACT FROM AUTHOR]

• The bulk FeMnSb exhibits half-metallic ferrimagnetism with 100% spin-polarization. • The MnSb-terminated surface maintains half-metallicity, essential for spintronic applications. • The Fe-Ga interface achieves 97.316% spin-polarized current, indicating strong spin-polarization. • Absorption coefficient peaks shift from the UV region in the bulk alloy to the visible region at the (001) surfaces. • At FeMnSb/GaAs and FeMnSb/GaP interfaces, the highest absorption peaks return to the UV region. We systematically investigated the electronic, magnetic, and optical properties of the FeMnSb half-Heusler alloy, its (001) surface, and its interfaces with GaAs and GaP semiconductors by using first-principles calculations based on density functional theory. The bulk FeMnSb reveals its half-metallic ferrimagnetism with 100% spin-polarization. Extending this study to the (001) surface, we uncover distinct electronic and magnetic behaviors for Fe- and MnSb-terminated surfaces, the MnSb-terminated surface preserving the half-metallicity observed in the bulk material. Our evaluation of the interfaces exhibits positive work of separation, indicating that these interfaces are energetically favorable. The density of states analysis reveals that all interfaces exhibit a metallic nature. High spin-polarization values, particularly 97.316% for the Fe-Ga interface, suggest a substantial degree of spin-polarized current. Notably, the absorption coefficient peaks shift from the ultraviolet (UV) region in the bulk alloy to the visible region at the (001) surfaces. However, at the FeMnSb/GaAs and FeMnSb/GaP interfaces, the highest absorption peaks revert to the UV region, highlighting strong interfacial coupling effects. These results suggest the tunability of FeMnSb optical properties via surface termination and interface engineering, making it a promising candidate for spintronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

All-d-metal full-Heusler alloys possess superior mechanical properties and high spin polarization, which would play an important role in spintronic applications. Despite this, their electrical and thermal transport properties have not been comprehensively investigated till now. In this work, we present an analysis on the evolution of structural, magnetic and transport properties of Cr- and Ti-substituted Fe 2 CrV all-d-metal Heusler alloys by combining theoretical calculations and experiments. Both series of alloys crystallize in Hg 2 CuTi-type structure. With increasing Ti doping, the calculated total magnetic moments of Fe 50 Cr 25 V 25-x Ti x decrease linearly. The experimental saturation magnetization is highly consistent with theoretical calculations and Slater-Pauling rule when x < 4, indicating the highly ordered atomic occupation. The magnetization and Curie temperature can be significantly tuned by altering spin polarizations and exchange interactions. The introduction of the foreign atom, Ti, results in a linear increase in residual resistivity, while electron-phonon scattering keeps relatively constant. The maximum values for electrical and thermal transport properties are observed in the stoichiometric Fe 2 CrV composition. • All-d-metal Heusler alloys Cr 75-x Fe x V 25 and Fe 50 Cr 25 V 25- x Ti x were realized. • The electrical and thermal transport properties were investigated. • The magnetization and Curie temperature can be significantly tuned. • The electron-phonon scattering remains constant for different Ti content. [ABSTRACT FROM AUTHOR]

The exchange bias effect is the physical basics of spin valves and magnetic recording devices. A stable exchange bias effect would be suitable for practical application. In this work, Ni 50 Mn 50- x Ga x (11≤ x ≤16) ribbons were obtained by melt spinning. The grain size and microstructure have been tuned through melt spinning, which changes the exchange interaction in ribbons and thus gets a giant and stable exchange bias effect. As the increase of x , the structure of Ni 50 Mn 50- x Ga x (11≤ x ≤16) ribbons undergoes a transition from non-modulated martensite to non-modulated martensite &10 layers modulated martensite to 10 layers modulated martensite. The average grain size of all ribbons is less than 10 μm, and the martensitic plate widths are smaller than 200 nm. With the increasing x or the cooling fields, the magnetization of the ribbons has been enhanced. As a result, the competition between ferromagnetic and antiferromagnetic interactions has been changed and thus influencing spin glass behavior. Furthermore, a low degree of attenuation for the exchange bias effect after continuous cycles has been achieved which arises from the stable spin configuration with a larger contribution of frozen spin which has a slow relaxation rate. For example, the exchange bias field of 8.78 kOe in Ni 50 Mn 38 Ga 12 ribbons can be achieved under the 40 kOe field cooling at 10 K, and the exchange bias field after infinite cycles can be kept at 8.58 kOe, the degree of attenuation is only 3.4 %. This work enriches the research on the exchange bias effect of Heusler alloys and provides the experimental basis and theoretical support for designing a stable exchange bias effect. • Through melt spinning, the structure and grain size of ribbons are both tuned. • A stable and giant exchange bias effect is obtained in Ni-Mn-Ga ribbons. • A stable spin configuration with a larger contribution of frozen spin is obtained. • The exchange bias effect can be tuned both by compositions and cooling fields. [ABSTRACT FROM AUTHOR]

In this study we have investigated the robust phase stability, elasto-mechanical, thermophysical and magnetic response of KVSb half Heusler compound by implementing density functional theory (DFT) models in WIEN2k simulation package. The dynamic phase stability is computed in phase type I, II & III phase configurations by optimising their energy. It is observed that given compound is more stable in spin-polarized state of phase type-III. To explore the electronic band structure, we apply the generalised gradient approximation along with Hubbard potential U. The electronic band profile of the Heusler alloy display a half-metallic nature. Moreover, the calculated second-order elastic parameters divulge the brittle nature. To understand the thermodynamical and thermoelectric stability of the alloy at various temperature and pressures ranges Quasi-Harmonic Debye model is executed successfully. The computed value of magnetic moment (MM) found in good agreement with Slater-Pauling rule. Our findings confirms that the predicted half Heusler alloy can be used in various spintronics and thermoelectric applications. [ABSTRACT FROM AUTHOR]