CuHg2Ti-type Structure Research Articles

Investigation of thermodynamic, magnetic, structural and electronic properties of full-Heusler Co2TiZ (Z=Si,Ge,Sn) alloys

Our expedition into the domain of materials science was an immersive journey, where we tapped into the dynamic synergy between density functional theory (DFT) and the FP-LAPW method. Guided by the enigmatic allure of full-Heusler Co2TiZ (Z=Si, Ge, Sn) alloys, our inquiry embarked on a quest marked by extensive analysis and profound discovery. Throughout this meticulous odyssey, we meticulously unraveled the complex tapestry woven by the structural, magnetic, and electronic properties inherent in both cubic CuHg2Ti-type and AlCu2Mn-type structures. Among the myriad revelations unearthed in our expedition, none stood as starkly as the remarkable stability exhibited by the ferromagnetic state, a stark departure from its nonmagnetic counterpart. This stability was further underscored by the presence of integer magnetic moments, serving as a defining characteristic of the ferromagnetic state. As our journey into the heart of materials science progressed, we peeled back layers of complexity to reveal a fascinating dichotomy within the density of states and band structure. Here, we witnessed a symphony of contrasting behaviors: while majority spins embraced semiconductor characteristics, minority spins danced to the metallic tune, painting a vivid portrait of the alloys' intrinsic half-metallic essence. Leveraging the GGA-PBE methodology, our investigation meticulously probed both fundamental and half-metallic gaps, thus unveiling a comprehensive portrait of the materials' electronic landscape. Moreover, our inquiry meticulously preserved a direct band gap at the X → X point, an essential facet imbued with profound implications for the materials' optoelectronic attributes. These insights, far from being confined to the realm of academic curiosity, serve as catalysts for transformative progress in materials design and optimization. By unraveling the intricate interplay between structure and electronic behavior, our findings lay a sturdy foundation for pioneering applications across diverse fields such as spintronics, catalysis, and energy conversion. In summation, our odyssey stands as a beacon guiding the way toward a new epoch of functional materials, poised to transcend the boundaries of technological innovation and unleash unprecedented capabilities across multifarious domains.

Computational study of structural stability, elastic, electronic, magnetic and thermodynamic properties of the Rh2-based full-Heusler compounds: Rh2MnZ (Z = Sn, Pb, Tl) by FP-LAPW method

The structural, elastic, electronic and thermodynamic properties as well as the magnetism of the ternary full-Heusler alloys Rh2MnZ (X = Sn, Pb and Tl) have been investigated by using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA). The AlCu2Mn-type structure is energetically more favorable than the CuHg2Ti-type structure for all the compounds studied here and found to be are ferromagnetic. The electronic structures calculations are found to exhibit a metallic character for all the herein studied compounds Rh2MnZ (X = Sn, Pb and Tl) alloys. The magnetic properties reveal that the Mn atom is responsible for large magnetic moment. Moreover, the mechanical behavior shows that all studied compounds are mechanically stable, ductile and anisotopic in nature. The elastic and thermodynamic properties for Rh2MnTl compound have not yet been established. The obtained results for various properties of the series of Rh2MnZ (X = Sn, Pb and Tl) are compared with those found experimentally and theoretically.

Ab Initio Investigations of the Structural, Electronic, Magnetic, and Thermal Properties of Cr2TaGe1-xSnx Quaternary Heusler Alloys

The first-principle calculations were performed in the framework of the density functional theory (DFT) using FP-LAPW method as implemented in Wien2k code to determine the structural stability, electronic, and magnetic properties of quaternary Heusler alloys Cr2TaGe1-xSnx (x = 0, 0.25, 0.50, 0.75, 1.00), The results showed that for the compounds, the AlCu2Mnl-type structure is energetically more stable than CuHg2Ti-type structure at the equilibrium volume. The calculated lattice constants for Cr2TaGe and Cr2TaSn are 6.081 A and 6.311 A, respectively. For mechanical properties, shear modulus, Young’s modulus, elastic constants, Poisson’s ratio and shear anisotropy factor have studied. Their obtained values reveal that these compounds are mechanically stable. The electronic band structures and density of states of our compounds show a half metallic character with total magnetic moments, − 3.00 μB per formula unit with indirect band gap, 0.569 eV and 0.482 eV for Cr2TaGe and Cr2TaSn respectively. Regarding thermal properties such as the thermal expansion coefficient, heat capacity, and Debye temperature, we have applied a very suitable model for studying thermodynamics quantities called the quasi-harmonic Debye model. On the basis of these results, these alloys are predicted to be good candidates for future spintronic applications.

First-Principle Calculations of the Structural, Electronic, and Thermal Properties of Cr2NbSn1 − xPbx Quaternary Heusler Alloys

The electronic structure, elastic, and magnetic properties of the Cr2NbSn1 − xPbx quaternary Heusler alloys have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory and implemented in WIEN2k code. The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) within the Perdew–Burke–Ernzerhof (PBE) parameterization. Our results provide a theoretical study for the mixed Cr2NbSn1 − xPbx Heusler alloys in which no theoretical or experimental data are currently available. The AlCu2Mnl-type (L21) structure is more stable than the CuHg2Ti-type structure at equilibrium volume for the compounds. In their equilibrium L21 structure, all concentrations are magnetic and metallic. However, there is linear variation of the lattice parameter. The bulk modulus, the elastic constants, and the Debye temperature were studied with a variation of composition x of Pb. The mechanical results show that these compounds are mechanically stable. The quasi-harmonic Debye model, as implemented in the Gibbs code, was used to predict the thermal properties of the Cr2NbSn1 − xPbx alloys. These alloys seem to be a potential candidate of spintronic devices.

Investigation of Electronic Structure, Mechanical, Magnetic Properties and Thermal Properties of Co<sub>2</sub>CrSi<sub>1-x</sub>Al<sub>x</sub> Quaternary Heusler Alloys: An Ab-initio Study

The structural, electronic and elastic properties of full- Heusler alloys Co2CrZ (Z=Si,Al) and their quaternary compound Co2CrSi1-xAlx, are determined using the full potential linearized augmented plane waves (FP- LAPW) method based on (GGA) the Generalized Gradient Approximation and density functional theory (DFT) implemented in the WIEN2k package. As results, quaternary compound in CuHg2Ti-type crystal structure are stable. Density of states (DOS) and bands structure show the existence of energies band gaps in their minority-spin channels with half-metallic behavior. The lattice constant of new quaternary alloys Co2CrSi1-xAlx exhibits a small deviation from Vegard's law and a marginal deviation of the bulk modulus from linear concentration. The three independent elastic constants (C11, C12, and C44) are calculated from the direct computation of the stresses generated by small strains. Besides, we report the variation of the elastic constants as a function of pressure as well. From the calculated elastic constants, the mechanical character of Co2CrSi1-xAlx is predicted; elastic constants are calculated to investigate stability criteria and the mechanical nature of the studied materials. The quaternary compound is found to be mechanically anisotropic, ductile and meet the elastic stability criteria. A regular solution model is used to investigate the thermodynamic stability of the alloy which essentially shows a miscibility gap phase by calculating the critical temperatures of the alloys.

First-principles calculations to investigate magnetic and thermodynamic properties of new multifunctional full-Heusler alloy Co2TaGa

The structural, elastic, electronic, magnetic and thermodynamic properties of Co2TaGa full-Heusler alloy are investigated using density functional theory-based full-potential linearized augmented plane waves method. Our results present Co2TaGa full-Heusler in CuHg2Ti-type structure FM phase that is mechanically and dynamically stable at pressure. The negative formation energy of Co2TaGa is −1.516 eV that can be synthesized experimentally. The electronic properties of 3d transition metal-based full-Heusler compound Co2TaGa are calculated within Perdew–Burke–Ernzerhof generalized gradient approximation. Co2TaGa is predicted to be half-metallic ferrimagnet with an indirect band gap and 100% spin polarization. The calculated total magnetic moment is 2 μB, which is mainly determined by Co partial moment, and total spin magnetic moment is in conformity with Slater–Pauling rule Mt that gives a simple function of valence electrons number, Zt, formulated as Mt = Zt − 18.

Half-metallic properties of the new Zr2RhB inverse Heusler alloy with CuHg2Ti–type structure

Abstract We examined the electronic and magnetic properties of the new inverse Heusler alloy Zr2RhB with CuHg2Ti–type structure, based on first principles calculation. We found that the Zr2RhB Heusler alloy appears to possess the half-metallic property, and that the spin-minority states are formed with an energy gap equal to 0.45 eV and a magnetic moment of 2.00 μᵦ/f.u. Finally, the Zr2RhB alloy appears to preserve a full-spin polarisation at the Fermi state, with a wide range of lattice constants, from 6.80 A to 7.70 A, thus forming an alloy appropriate for applications of the spintronic.

Electronic Structure and Half-Metallicity in the Zr2RuZ (Z = Ga, In, Tl, Ge, Sn, and Pb) Heusler Alloys

The electronic structures, magnetic properties and half-metallicity in Zr2RuZ (Z = Ga, In, Tl, Ge, Sn, and Pb) alloys with AlCu2Mn- and CuHg2Ti-type structures were investigated using first-principles density functional theory (DFT) calculations. The calculations showed that Zr2RuIn, Zr2RuTl, Zr2RuSn, and Zr2RuPb compounds with CuHg2Ti-type structures were half-metallic ferromagnets with half-metallic band gaps of 0.18, 0.24, 0.22, and 0.27 eV, respectively. The half-metallicity originated from d-d and covalent hybridizations between the transition metals Zr and Ru. The total magnetic moments of the Zr2RuZ (Z = In, Tl, Sn, and Pb) compounds with CuHg2Ti-type structures were integer values of 1μB and 2μB, which is in agreement with Slater-Pauling rule (Mtot = Ztot − 18). Among these compounds, Zr2RuIn and Zr2RuTl were half-metals over relatively wide regions of the lattice constants, indicating that these two new Heusler alloys are ideal candidates for use in spintronic devices.

Study of Electronic Structure, Magnetism, and Half-Metallicity of New Heusler Compounds CsTmO2 (Tm = Fe, Co, Ni, and Cu)

The density functional calculations were performed using the full-potential linearized augmented plane wave (FPLAPW) method for new Heusler alloys CsTmO2 (Tm = Fe, Co, Ni, and Cu). All compounds were stable in FM AlCu2Mn-type structure. Results revealed that these alloys can be experimentally synthesized according to the calculated cohesive and formation energies. CsTmO2 (Tm = Fe, Co, Ni, and Cu) alloys in AlCu2Mn-type and CuHg2Ti-type structures were half-metallic ferromagnets. The origin of half-metallicity in CsNiO2 alloy was also discussed. The total magnetic moment of CsTmO2 (Tm = Fe, Co, Ni, and Cu) alloys in both structures were 3 μB per formula unit and obeyed the Slater-Pauling rule (Mtot = 22 − Ztot). The relationship between the magnetism and half-metallicity of all compounds and the lattice constants was also studied. The half-metallic character in combined alloys CsTmO2 (Tm = Fe, Co, Ni, and Cu) improved in comparison with Heusler alloys including transition metals which indicated that they may be good candidates for practical applications in spintronics.

First-Principles Study in New Hf2CoZ (Z = B, C, Al, Si, Ga, Ge, In, Sn, Tl, and Pb) Heusler Alloys

The full-potential linearized augmented plane wave method within density functional theory was used to investigate the electronic structures, magnetic properties, and half-metallicity in Hf2CoZ (Z = B,C, Al, Si, Ga, Ge, In, Sn, Tl, and Pb) alloys with AlCu2Mn- and CuHg2Ti-type structures. The AlCu2Mn-type structure is energetically favorable than the CuHg2Ti-type structure for all compounds. Hf2CoGa, Hf2CoAl, Hf2CoIn, Hf2CoTl, and Hf2CoSn compounds in the CuHg2Ti-type structure were half-metallic ferromagnets. The d-d and covalent hybridizations between transition metals Hf and Co were effective in the formation of minority band gap. The total magnetic moments of half-metallic Hf2CoZ (Z = Al, Ga, In, Sn, and Tl) compounds in the CuHg2Ti-type structure obeyed the Slater–Pauling rule (M tot = Z tot − 18). Hf2CoIn and Hf2CoTl compounds were half-metals in relatively wide ranges of lattice constants which indicates that they can be promising and interesting candidates for spintronic devices.

Density Functional Study of Half-Metallic Ferromagnetism in the New Heusler Compounds CaYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn)

The structural, electronic, and magnetic properties of full-Heusler alloys CaYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) were investigated using full-potential linearized augmented plane wave method based on density functional theory. It was confirmed that these compounds can be synthesized experimentally due to their negative formation energies. The results predicted that all compounds in AlCu2Mn-type structure were more stable than CuHg2Ti-type structure. The band structure calculations showed that alloys CaYO2 (Y = Cr, Fe, Ni, and Cu) in AlCu2Mn-type structure and CaYO2 (Y = Ti, V, Cr, Co, and Ni) in CuHg2Ti-type structure have half metallic behavior. The origin of half-metallic characteristic was investigated using electronic density of states for CaFeO2. Among these alloys, CaCrO2 was half-metal in a wide range of lattice constants indicating its resistance against destructive factors of half-metallicity such as temperature and pressure. The total magnetic moments for half-metallic alloys were integer values and obeyed the Slater-Pauling rules. The CaYO2 alloys with half-metallic character may be good candidates for practical applications in spintronics.

Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y=Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot=22-Ztot and Mtot=32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

Prediction of Half-metallicity in the New Heusler CsYX 2 (Y = Sc, Ti, V, Cr, and Mn; X = O and N) Compounds

Electronic structure calculations based on density functional theory of the new Heusler CsYX 2 (Y = Sc, Ti, V, Cr, and Mn; X = O and N) compounds were performed using the full-potential linearized augmented plane wave (FPLAPW) method. These compounds can be synthesized experimentally because of their negative formation energies. The CsYX 2 compounds were stable in an AlCu2Mn-type structure. CsScN2, CsTiO2, CsVN2, CsCrO2, and CsMnN2 compounds in the AlCu2Mn-type structure and CsScN2, CsTiO2, CsVO2, and CsMnO2 in an CuHg2Ti-type structure were half-metallic (HM) feromagnets. CsVO2 in the AlCu2Mn-type structure was a spin-gap less semiconductor. The origin of half-metallicity for CsCrO2 was verified using the partial density of states. The Slater-Pauling rules were used to determine the total magnetic moments of the HM CsYX 2 compounds. Furthermore, CsYX 2-combined alloys had the widest regions of half-metallictiy in comparison with the Heusler alloys including transition metals, indicating that they may be promising materials for spintronic applications.

Half-metallicity and magnetism of the full-Heusler compounds KYX 2 (Y=Ti, V, and Cr; X=C, N, and O)

Abstract The electronic structure and half-metallic (HM) properties of new alloys KYX2 (Y=Ti, V, and Cr; X=C, N, and O) containing transition metals and sp elements were investigated within the density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It was found that these new compounds can be experimentally synthesized because of their negative formation energies. The total energy calculations showed that in all compounds, the stable state structure was a ferromagnetic AlCu2Mn-type structure except for KTiC2 and KTiN2 which were stable in a nonmagnetic (NM) AlCu2Mn-type structure. The KTiO2 in both structures, KCrO2 in AlCu2Mn-type structure, and KVO2 in CuHg2Ti-type structure were half-metallic ferromagnets. KVO2 in AlCu2Mn-type structure was a special case with a ferromagnetic semiconducting behavior. The origin of minority band gaps for KTiO2 in both structures was also studied using the band structure calculations. The total magnetic moments of HM compounds were integer values which were in agreement with Slater-Pauling rule (Mtot=Ztot−12). Furthermore, the regions of half-metallictiy in HM compounds were considerably wider than those of Heusler compounds including transition metals, indicating the high robustness of half-metallicity with variation of lattice constants.

The effect of pressure on the structural, electronic, magnetic, and thermodynamic properties of the Mn2RuGe inverse Heusler alloy

In the frame of density functional theory, first-principles calculations based on generalized gradient approximation and quasi-harmonic Debye approximation model in which the phononic effects are taken into account have been carried out to investigate the structural, electronic, magnetic, and thermodynamic properties of full-Heusler alloy Mn2RuGe in CuHg2Ti-type structure in the pressure range of 0–50GPa. Present calculations predict that Mn2RuGe is a ferrimagnet with an optimized lattice parameter of 5.854Å. The calculated total magnetic moment of 2.01μB per formula unit is very close to integer value and agree well with the Slater-Pauling rule, where the partial spin moments of Mn (A) and Mn (B) which mainly contribute to the total magnetic moment are 2.66μB and −0.90μB, respectively. In the study of the energy band structures and density of states, Mn2RuGe exhibits half-metallicity with an indirect gap of 0.235eV in the spin-down channels, and the shifting of bands towards higher energies in spin-down channel under high pressure. Meanwhile, the high-pressure thermodynamic properties of Mn2RuGe, such as the pressure-volume-temperature relationship, bulk modulus, thermal expansivity, heat capacity, Debye temperature, and Grüneisen parameter are evaluated systematically in the temperature range of 0–900K. This set of data is considered as the useful information to understand the high-pressure and high-temperature properties for the Mn2RuZ-type Heusler alloy family.

High-pressure and high-temperature physical properties of half-metallic full-Heusler alloy Mn2RuSi by first-principles and quasi-harmonic Debye model

First-principles calculations based on density functional theory and quasi-harmonic Debye model are used to investigate the high-pressure and high-temperature physical properties, including the lattice constant, magnetic moment, density of states, pressure-volume-temperature relationship, bulk modulus, thermal expansivity, heat capacity, and Grüneisen parameter for the new Mn-based full-Heusler alloy Mn2RuSi in CuHg2Ti-type structure. The optimized equilibrium lattice constant is consistent with experimental and other theoretical results. The calculated total spin magnetic moment remains an integral value of 2.0μB in the lattice constant range of 5.454–5.758Å, and then decreases very slowly with the decrease of lattice constant to 5.333Å. By the spin resolved density of states calculations, we have shown that Mn2RuSi compound presents half-metallic ferrimagnetic properties under the equilibrium lattice constant. The effects of temperature and pressure on bulk modulus, thermal expansivity, heat capacity, and Grüneisen parameter are opposite, which are consistent with a compression rate of volume. Furthermore, the results show that the effect of temperature is larger than pressure for heat capacity and the effect of high temperature and pressure on thermal expansion coefficient is small. All the properties of Mn2RuSi alloy are summarized in the pressure range of 0–100GPa and the temperature up to 1200K.

Half-metallicity in the inverse Heusler Ti2RuSn alloy: A first-principles prediction

The electronic and magnetic properties of the Ti2RuSn Heusler compound are investigated by means of ab initio calculations with the full-potential linearized augmented plane wave (FLAPW) method. The generalized gradient approximation (GGA) method is used for the calculations. The CuHg2Ti-type structure is energetically more stable than the AlCu2Mn-type structure. The inverse-Heusler Ti2RuSn represents half-metallic behavior. The total spin moment of the compound is 2μB which coincides with the Slater–Pauling rule of Mt=Zt−18 with the equilibrium lattice constant a0=6.44Å and the strained lattice constants as well. The majority bands have metallic properties, but the minority bands have semiconductor properties with a gap of 0.35eV, and the spin-flip gap is 0.23eV. Moreover, the sensitivity of half-metallicity is investigated under two types of structural distortion, namely uniform strain and tetragonal distortion.

Magnetism and Half-Metallicity in the Fe2ZrP Heusler Alloy

The electronic structure and magnetic properties of the Fe2ZrP full-Heusler compound has been investigated by using ab initio calculations with the full-potential linearized augmented plane wave (FLAPW) method. The exchange-correlation functionals are taken into account within the generalized gradient approximation (GGA). Energetically, the AlCu2Mn-type structure of the full-Heusler Fe2ZrP is energetically more preferable than that of the CuHg2Ti-type structure and it exhibits half-metallic ferrimagnet. The calculated total spin moment is found as 1 μ B at the equilibrium lattice constant a 0=5.90A which remarkably agrees with the Slater-Pauling rule of M t = Z t −24. While the spin-up band is metallic, the spin-down band has a semiconductor behavior with a gap of 0.593 eV and the spin-flip gap is 0.129 eV. The negative formation energy is shown as an evidence of the thermodynamic stability of alloy. The dependencies of the magnetic and electronic properties on the lattice constant are also discussed. The estimated Curie temperature is 752 K in the mean field approximation.

Half-Metallic Properties of the Ru2ZrSb Full-Heusler Compound: a First-Principles Study

A first-principles study on the electronic structure and magnetic properties of the Ru2ZrSb Heusler compound has been performed by using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method. It is found that the AlCu2Mn-type structure exhibits half-metallic ferrimagnetism and is preferable energywise than the CuHg2Ti-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 Ru2ZrSb is −1.0 μ B at the equilibrium lattice constant 6.497 A for the AlCu2Mn-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 AlCu2Mn-type Ru2ZrSb Heusler compound keeps a 100 % of spin polarization for lattice constants ranging between 6.40 and 6.53 A. The Curie temperature is estimated to be 322.7 K in the mean field approximation (MFA).

Prediction of the Half-Metallic Properties of Zr2VZ (Z = Si, Ge, Sn, and Pb) Heusler Alloys Based on Density Functional Theory

Density functional theory plane-wave pseudo-potential methods were used to study the electronic structures, magnetic properties, and half-metallic nature of Zr 2VZ (Z = Si, Ge, Sn, and Pb) alloys. Electronic-structure calculations show that the Zr 2VZ (Z = Si, Ge, Sn, and Pb) alloys in the AlCu 2Mn-type structure are conventional ferrimagnets. However, in the CuHg 2Ti-type structure, these alloys are half-metallic ferrimagnets. In addition, the half-metallic states and magnetism versus the lattice constant of the Zr 2VZ (Z = Si, Ge, Sn, and Pb) alloys in the CuHg 2Ti-type structure have been tested. The calculated total magnetic moment of the Zr 2VZ (Z = Si, Ge, Sn, and Pb) alloys in the CuHg 2Ti type is 1 μ B per unit cell, which is in line with the Slater-Pauling curve of the total magnetic moment (M t) = 18 − Z t.