Equiatomic Quaternary Heusler Research Articles

Investigating Structural, Mechanical, Electronic and Magnetic Properties of Spin-Gapless Quaternary Heusler Alloy Crmnval

Utilizing density functional theory (DFT), the study thoroughly investigates the equiatomic quaternary Heusler compound CrMnVAl, revealing its promising properties across multiple domains. The energy minimization curve shows its structural stability with lattice parameter 5.91Å in ferromagnetic phase. The negative values of formation and cohesive energy indicate its chemical stability, while electronic structure analysis demonstrates spin gapless semiconducting behavior. The total spin magnetic moment of this compound is almost 3.00 μB obeying the Slater-Pauling 18 electron rule (Mt = Zt – 18). The 100% spin polarisation and the Curie temperature higher than ambient temperature indicate that this compound acts as a promising material for spin dependent applications. Furthermore, exploring its mechanical properties complements these findings, offering insights into its structural integrity and suitability for diverse applications. Overall, the study underscores CrMnVAl's potential as a versatile material for spintronics and beyond.

Structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of a new equiatomic quaternary heusler compound FeZrCrZ (Z = Si, Ge, Sn): A first-principles investigation

In this investigation, we undertake an ab initio exploration of the structural, mechanical, electronic, magnetic, optical, and thermoelectric characteristics of equiatomic quaternary Heusler compounds (EQH), specifically FeZrCrZ (Z = Si, Ge, Sn). Our investigation involves the utilization of the full-potential linearized augmented plane wave method (FP-LAPW) in density functional theory (DFT) framework, employing the generalized gradient approximation (GGA). The findings reveal that the Y-type-I arrangement, demonstrating ferromagnetic alignment, emerges as the most thermodynamically favored configuration among all FeZrCrZ (Z = Si, Ge, and Sn) compounds. Computed values for formation energy substantiate the feasibility of experimental synthesis.Furthermore, we meticulously determine elastic constants, confirming the structural robustness of the quaternary compounds. Dynamic stability analysis reinforces their stability. Electronic property assessments unveil the semi-metallic nature of FeZrCrZ (Z = Si, Ge, and Sn) alloys, showcasing complete spin polarization at the Fermi energy (100 %), a minimal energy gap, and magnetic moments of 2 μB when Z = Si, Ge, and 4 μB when Z = Sn. Optical property calculations encompass complex refractive index, dielectric function, reflectivity, absorption coefficient, and optical conductivity, indicating potential suitability of these compounds for optoelectronic applications. Employing Boltzmann transport theory, we investigate the thermoelectric performance of the compounds concerning temperature, and chemical potential. Evaluation of the thermoelectric response underscores their viability as thermoelectric materials, linked to a substantial figure of merit, increased Seebeck coefficient, and diminished thermal conductivity. This study provides crucial theoretical insights for experimental researchers, offering valuable information for the synthesis and application of these compounds in spintronics, thermoelasticity, and optoelectronics.

Exploring FeMnVAl Heusler Alloy: Physical, Mechanical, and Magnetic Properties

The structural, mechanical, electronic, and magnetic properties of equiatomic quaternary Heusler alloy FeMnVAl have been investigated using first-principles approach. This alloy shows ferromagnetic ground state structure with chemical stability indicating compound fulfills the criteria for synthesizing experimentally. The calculated values of Pugh’s index and Poisson’s ratio confirmed ductile nature of FeMnVAl. The investigation of band structure and density of states validates the behaviour of half[1]metallic ferromagnetism (HMFs), which follow the Slater-Pauling rule Mt = Zt - 24 and have a magnetic moment value of around 1 μB/f.u. Its features also allow for potential applications in the realm of spintronics devices and optoelectronics.

Griffiths phase like behaviour in CoCrVZ (Z = Al, Ga) Heusler alloys

We report here the studies of structural and magnetic properties of two equiatomic quaternary Heusler alloys CoCrVZ (Z = Al, Ga). Both the alloys crystallize in LiMgPdSn type crystal structure (space group #216) with B2 (CoCrVAl) and A2 (CoCrVGa) type anti-site disorder between elemental sites. Intended stoichiometry was confirmed from the compositional analysis. The temperature dependence of dc magnetic susceptibility and the low temperature moment values show a nearly compensating ferrimagnetic behaviour at low temperatures for both the alloys. The inverse of dc magnetic susceptibility starts to deviate from the Curie–Weiss law below 220 K and 164 K for the alloys containing Al and Ga respectively. The Arrott plots confirms the absence of long range order down to 2 K. Further analysis of the dc and ac susceptibility shows that the observed behaviour is due to the presence of Griffiths like phase in these alloys.

A DFT calculation of electronic structures, magnetic, and thermoelectric properties of the new equiatomic quaternary Heusler alloy RuTiCrSi

AbstractThe stabilities, mechanical, electronic, and magnetic properties of the new equiatomic quaternary Heusler alloy (EQHA) RuTiCrSi were investigated using the Kohn‐Sham DFT (KS‐DFT) calculations within the generalized gradient approach (GGA), the modified version of the exchange potential introduced by Becke and Johnson in addition to the GGA (mBJ‐GGA), and Heyd‐Scuseria‐Ernzerhof (HSE06) hybrid functional. The ground‐state equilibrium energy reveals that the ferromagnetic with type 2 structure is the more stable. The RuTiCrSi is energetically, mechanically, and dynamically stable. The calculated self‐consistent total magnetic moment is 2 μB and agrees well with the Slater‐Pauling rule of . The electronic structure results from mBJ‐GGA and HSE06 functionals show a half‐metallic behavior. A high Curie temperature is obtained using the mean‐field approximation. The thermoelectric response was calculated using the semi‐classical Boltzmann transport equation under constant relaxation time. The maximum value of Seebeck coefficient is observed at the ambient temperature of . It was also observed that the power factor increases significantly as temperature rises. Therefore, the new EQHA RuTiCrSi seems to be a potential candidate for spintronic thermoelectric applications.

First-principles study on rare earth-based equiatomic quaternary Heusler alloys YbCoCrSb and YbCoTiSn: New candidates for spintronics

We have investigated the structural, mechanical, thermal, electronic, magnetic, and half-metallic properties of new Yb-based EQHAs such as YbCoCrSb and YbCoTiSn using first-principles calculations. We computed the ground state properties of different possible crystal structures and magnetic states. We also calculated their elastic constants and derived mechanical parameters, including bulk, shear, and Young's moduli, as well as Poisson's and Pugh ratios. The electronic structure of both EQHAs shows half-metallic behavior with a spin down band gap of 0.39 eV for YbCoCrSb and 0.30 eV for YbCoTiSn in the GGA-PBE scheme. The estimated total spin magnetic moment has a positive integer value, which is well in accordance with the Slater-Pauling rule of 18. Because of the nearly closed f orbital shell of the Yb atom, the total spin magnetic moment is mainly dependent on 3d transition metal atoms. These alloys exhibit TC > 300 K using the mean field approximation.

Effect of swap and antisite disorder on electronic, mechanical and thermodynamic properties of equiatomic all-d-metal Heusler alloy NiVTiZn

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

Critical behavior, structural, electronic, and magnetic properties of the Heusler alloy: CoFeCrP

In this work, we study the equiatomic quaternary Heusler alloy (EQHA) CoFeCrP using two methods: density functional theory (DFT) and Monte Carlo simulations. The DFT method allowed us to illustrate the structural, electronic, and magnetic properties of this alloy. The ground state phase diagrams have been presented to show the stable configurations in different physical parameter planes. On the other hand, the Monte Carlo simulations, performed under the Metropolis algorithm, permitted to deduce the critical the behavior of the EQHA CoFeCrP. The structural properties results show that the phase of type I, of this alloy is the most stable configuration. In addition, the band structures and density of states calculations results show that this compound exhibits a half-metallic character with a 100% of spin polarization (SP) at the Fermi-level. The total magnetic moment of the Heusler compound is found to be 4.00 µB. Moreover, it is found that the Slater-Pauling is well described for this alloy. Our results show that this material is a potential candidate for the spintronic applications. This is due to its half-metallicity, its high spin moments, its complete SP polarization, and its high Curie temperature.

Experimental realization of CoFeRuSn quaternary Heusler alloy for room temperature spintronic applications

We synthesize CoFeRuSn equiatomic quaternary Heusler alloy using arc-melt technique and investigate its structural, magnetic, and transport properties. The room temperature powder x-ray diffraction analysis reveals that CoFeRuSn crystallizes in cubic crystal structure with small amount of DO3-disorder. The field dependence of magnetization shows non-zero but small hysteresis and saturation behavior up to room temperature, indicating soft ferromagnetic nature of CoFeRuSn. The magnetic moment estimated from the magnetization data is found to be 4.15 μB/f.u., which is slightly less than the expected Slater–Pauling rule. The deviation in the value of experimentally observed moment from the theoretical value might be due to small disorder in the crystal. The low temperature fit to electrical resistivity data shows the absence of quadratic temperature dependence of resistivity, suggesting half-metallic behavior of CoFeRuSn. The high Curie temperature and possible half-metallic behavior of CoFeRuSn make it a highly promising candidate for room temperature spintronic applications.

First-principles investigation on structural, electronic, magnetic, mechanical and thermodynamic properties of half-metallic Zn-based all-d-metal equiatomic quaternary Heusler alloys

This study employs first-principles calculations based on density functional theory (DFT) to investigate the structural, electronic, magnetic, mechanical, and thermodynamic properties of Zn-based all-d-metal equiatomic quaternary Heusler alloys (EQHAs) XX'YZn (X = Fe, Ni, Co; X' = V, Cr; Y = Nb, Ti, Zr, Hf). The investigation encompasses three distinct structural types of all-d EQHAs, with the energy calculations revealing the Type-I configuration as the most stable. The electronic structure of the all-d EQHAs demonstrate 100% spin polarization. Specifically, NiVTiZn and NiVZrZn exhibit characteristics of half-metallic ferromagnets, while FeVNbZn, CoCrTiZn, CoCrZrZn, and CoCrHfZn manifest traits of half-metallic ferrimagnets. Notably, we have conducted computations concerning the magnetic properties of these six alloys, revealing that their principal magnetic moments stem from V and Cr atoms. This study analyzes the influence of lattice constant variations on the magnetic properties of the alloys and the width of the spin down energy gap. Results demonstrate that within the ranges of lattice constants from 5.6 Å to 6.4 Å for FeVNbZn, 5.5–6.6 Å for NiVTiZn, 5.8–6.8 Å for NiVZrZn, 5.8–6.7 Å for CoCrTiZn, 5.9–6.8 Å for CoCrZrZn and 6.0–6.9 Å for CoCrHfZn, these alloys maintain their stable half-metallic attributes. Furthermore, the investigated alloys demonstrate mechanical stability, exhibiting ductility and anisotropic characteristics. These investigations underscore the potential application prospects of half-metallic all-d EQHAs in spintronic devices.

Coexisting cubic and tetragonal phases with ferrimagnetism in equiatomic quaternary Heusler alloys: CuTCrAl (T = Co and Fe)

We have investigated two equiatomic quaternary Heusler alloys CuTCrAl (T = Co and Fe) theoretically and experimentally. Both the alloys have been characterized using X-ray Diffraction (XRD) and neutron powder diffraction (NPD). Refined results of XRD and NPD show the presence of A2/B2 type disorder with the coexistence of mixed-phase of cubic and tetragonal symmetries in CuFeCrAl and CuCoCrAl. NPD magnetic structure refinement indicates the presence of ferrimagnetism with a very low moment at low temperatures. DC magnetization results reveal the presence of weak itinerant ferromagnetic behaviour. Temperature dependence resistivity reflects the metallic character with the presence of weak localization at low temperatures. The coexistence of cubic/tetragonal and ferrimagnetism along with metallic nature in a single system is quite rare, revealing the potential of these alloys for multifarious applications.

Atomic disorder, magnetic and electronic properties of equiatomic quaternary Heusler alloy FeRuCrSi: Experimental and theoretical investigations

The equiatomic quaternary Heusler alloy FeRuCrSi was synthesized and its atomic ordering, magnetic properties and electronic structure were investigated experimentally and theoretically. The FeRuCrSi formed a single Heusler phase and had a lattice constant of 5.811 Å at room temperature. An L21B-type disorder related to the random occupation of Fe and Ru at 4a and 4b sites was identified in the X-ray diffraction pattern. The Curie temperature of FeRuCrSi was 346 K and the saturation magnetization at 5 K was 1.84 μB/f.u., which is smaller than the integral value of 2.00 μB required for ideal spin gapless semiconductor character and is likely related to the L21B-type disorder. First-principles calculations revealed that ordered FeRuCrSi with YII-type structure had the lowest total energy at 0 K. However, the energy difference between it and the L21B structure was only 0.09 eV/f.u., thus the L21B disorder dominated in the experimental sample because of the enthalpy of mixing and the “freezing” of high-temperature disorder at room temperature. The YII-type FeRuCrSi was a SGS with a half-metallic gap in the minority density of states (DOS) and a zero-width gap in the majority DOS. However, the L21B-type disorder disturbed the SGS character by narrowing the two gaps. The total spin moment of ordered FeRuCrSi was 2.00 μB/f.u., mainly determined by the antiparallel coupled Cr and Fe/Ru spin moments. However, the total moment was slightly reduced in L21B-type FeRuCrSi. All this suggests that the possible L21B disorder should be carefully considered when designing and synthesizing half-metals/SGS in Heusler alloys for spintronic applications.

Experimental observation of spin glass state in the highly disordered quaternary Heusler alloy FeRuMnGa

The realization of the spin-glass (SG) state in Heusler alloys is very rare despite the presence of inherent structural and elemental disorder in those compounds. Although a few half- and full-Heusler alloys are known to exhibit the SG state, there is hardly any manifestation of the same in cases of quaternary Heusler compounds. Here we report the observation of a SG state in a highly disordered equiatomic quaternary Heusler compound: FeRuMnGa where the SG state is in between the canonical SG and the cluster glass. Different intricate features of the SG state including nonequilibrium magnetic dynamics at low temperatures in the compound are unveiled through our comprehensive magnetic, heat capacity, and neutron-diffraction studies. The structural disorder in the sample is neither conventional $A2$- nor $B2$ -type whereas those two types are commonly observed for Heusler compounds. The presence of disorder also plays a significant role in electron transport properties of the alloy, which is reflected in its exhibition of semimetallic behavior and anomalous Hall effect at low temperatures.

Pressure dependent electronic, spintronic, optical and mechanical properties of equiatomic quaternary Heusler alloys NbMnVAl and NbFeCrAl

The pressure dependent physical properties of Nb-based equiatomic quaternary Heusler alloys NbMnVAl and NbFeCrAl have been investigated using full-potential linearized augmented plane wave (FP-LAPW) method with exchange and correlation potentials of the PBEsol scheme. Half-metallic behavior in NbMnVAl (NbFeCrAl) with band gap of 0.32 (0.29) eV in spin-down (spin-up) state at ambient pressure is observed. The total magnetic moments are derived as 2.0 μΒ/f.u. for NbMnVAl and NbFeCrAl alloys, which reconciles with Slater-Pauling rule. Phonon frequencies are computed using Vienna Ab initio Simulation Package (VASP). The exchange interactions and Curie temperatures are determined using spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method. Moreover, the computations of mechanical properties revealed the stability and ductile nature of both compounds. The optical properties proved the applicability of these compounds in optoelectronic devices. Pressure dependent half-metallic properties are discussed to show spintronic applications of both the quaternary alloys.

Investigating the structural, electronic, and elastic properties of Li-based quaternary Heusler alloy semiconductors using hybrid functional – HSE06 bandgap recalculations

In this work, we introduce a new class of stable semiconducting equiatomic quaternary Heusler alloys. The 21 new semiconductors reported in this work contain 18 valence electrons per unit cell.Three different structural arrangements, referred Y1,Y2 and Y3 are taken into consideration. The bandgaps are investigated and significantly underestimated by GGA-PBE functional. We recalculated them by means of the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional to achieve the correct ones. This study shows that the HSE06 correction mainly acts on the lowest conduction bands. The energy gaps of the quaternary Heusler semiconductors are in the range of 0.766–1.94 eV, which suggests that these semiconductors are prospective materials for a variety of applications, including thermoelectric, optoelectronic, and photovoltaic. Furthermore, formation energy, elastic constants, and phonon dispersion curves are calculated to verify the mechanical and dynamical stabilities of these alloys.

An insight on the origin of half-metallicity of new equiatomic quaternary Heusler alloys PtRuTiZ (Z = Al/Si): GGA and GGA + U approaches

In this paper, we have presented a comparative investigation of a new equiatomic quaternary Heusler alloy PtRuTiZ (Z = Al and Si) under the GGA and GGA + U schemes and search for its possibility as a half-metallic material for spintronic devices. These alloys, which crystallize in a magnetic phase of LiMgPdSn (Y-type) structure with space group F-43 m, are thermodynamically and mechanically stable. The electronic properties predict these materials to be half metal under the GGA + U scheme considering the strong exchange splitting among the d – orbital of transition metals with a half-metallic gap of 0.07 eV and 0.1 eV for PtRuTiAl and PtRuTiSi, respectively signifying their prospect in power electronic applications. Here, PtRuTiSi is rigid and stiffer than PtRuTiAl and their magnetic properties also follow the Slater – Pauling rule of MT = ZT – 24 under the GGA + U scheme. The high range of pressure that PtRuTiSi (-1 GPa to 14 GPa) can retain its half-metallic behavior as compared to PtRuTiAl (-3 GPa to 4 GPa) may be linked to their bulk modulus.

Structural, magnetic, and transport properties of epitaxial thin films of equiatomic quaternary CoFeCrGa Heusler alloy

We present the first report on the structural, magnetic, and transport properties of epitaxial thin films of equiatomic quaternary CoFeCrGa, grown on a single crystal MgO(001) substrate. From the structure and surface morphology analyses, we have shown that the films grown are ordered, epitaxial, and homogeneous. Magnetic measurements confirm the soft ferromagnetic nature of the film along the in-plane direction with a coercivity of 4.6 Oe. The resistivity measurements indicate semiconducting nature with a very low temperature coefficient of resistivity (TCR) value, suggesting an almost temperature independent resistivity, similar to other reported spin-gapless semiconductors (SGSs) among the Heusler alloys. A non-saturating, quantum linear magnetoresistance is observed even in high fields of up to 12 kOe, another prerequisite for gapless materials. Hall measurements are also performed, and a detailed analysis has been carried out to estimate the ordinary and anomalous Hall contributions. The conductivity value (σxx) at 300 K is found to be 4280 S cm−1, which is comparable with the other reported SGS materials. We have also studied the effect of L21 and B2 type disorder on the electronic properties based on the first principle calculations and found that the SGS nature in CoFeCrGa is quite robust against the Co–Fe swap disorder (L21 disorder); however, with swap disorder (≥25%) between Cr and Ga sites, the system transits from SGS to half-metallic state. All these results indicate the possibility of spin-gapless semiconducting nature in the CoFeCrGa film, making it highly suitable for spin-based device applications.

Investigation of the physical properties of CoRuVAl equiatomic quaternary Heusler alloy using first-principles calculations

We have computed the structural, mechanical, and thermal stability, as well as electronic, magnetic, and transport properties of the CoRuVAl equiatomic quaternary Heusler alloy. The electronic structure of the CoRuVAl alloy shows an indirect band gap of 0.279 eV at Fermi level in the spin down channel and metallic overlap in the spin up channel, indicating the presence of half-metallic behavior. This alloy exhibits a robust half-metallicity during lattice deformation. The effect of changing Hubbard values on the electronic structure was also investigated. We have studied the inclusion of spin orbit coupling (GGA + SOC) in the electronic structure due to the presence of heavier atoms, including Ru. We have calculated spin-dependent transport coefficients, including Seebeck coefficient, thermal conductivity, and electrical conductivity for both spin configurations by varying the temperature, and this alloy could be used in the future in both spintronic and thermoelectric devices.

Magnetic properties and possible martensitic transformation in equiatomic quaternary Heusler alloy CoMnNiSn

Equiatomic quaternary Heusler alloy CoMnNiSn has been synthesized in both bulk and ribbon form to explain the contradictions in the magnetic properties and possible martensitic transformation between different literature. The structure, magnetic properties and electronic structure of CoMnNiSn were investigated both theoretically and experimentally. A cubic Heusler phase can be identified in the XRD patterns. A small amount of secondary phase is observed in bulk CoMnNiSn while it is eliminated in the melt-spun ribbons. The saturation magnetization Ms at 5 K of bulk and ribbon CoMnNiSn are 4.85 μB/f.u. and 4.76 μB/f.u., respectively. This and also the calculation results suggest that ferromagnetic ground state has been established in CoMnNiSn samples. There is no trace of martensitic transformation in CoMnNiSn bulk and ribbon samples. The L21B atomic disorder can be responsible for this, which comes from the random occupation of Co/Ni at A, C sites in the cubic lattice of CoMnNiSn and has a higher stability comparing with the ordered Y-type structure. This suppression effect is further explained by the weakening of the Jahn-Teller effect in the austenite DOS of L21B type CoMnNiSn. All this calls for more attention to the effects of atomic disorder in the design of magnetic shape memory alloys in equiatomic quaternary Heusler alloys.

First-principles calculations on novel Co-based Equiatomic Quaternary Heusler Alloys for Spintronics

The structural, mechanical, electronic, and magnetic properties of the new series of Co-based Equiatomic Quaternary Heusler Alloys (EQHAs) XX'YZ (X = Co; X' = Zr, Ru; Y = Ti, V; Z = Sn, Al, Ga, Si, Ge) have been calculated using first-principles calculations. The Full Potential-Linearized Augmented Plane Wave (FP-LAPW) approach was used in association with Density Functional Theory (DFT). We treated the exchange-correlation (XC) energy functional using a Generalized Gradient Approximation (GGA) in the Perdew-Burke-Ernzerhof (PBE) scheme. We included the TB-mBJ potential (GGA-mBJ) and the Hubbard correction (GGA + U) to improve the precision of the band gap values. Spin-orbit coupling (GGA-SOC) calculations are required due to the existence of heavier elements such as Zr and Ru. We have included the GGA-SOC calculations to estimate the total and partial magnetic moment and their impact on the electronic structure of Co-based EQHAs. The ground state parameters of proposed Co-based EQHAs were determined, including the lattice parameter, total energy, bulk modulus, and its derivative. The electronic structure of these materials revealed the presence of half-metallic ferromagnetism and spin-gapless semiconductor behavior. In addition, the origin of the band gap in spin channels was also investigated. In addition, we employed the mean-field approximation (MFA) method based on the Heisenberg model to determine the Curie temperature (TC). This theoretical analysis adds a new level of sophistication to the application of Co-based EQHAs in spintronic applications.