AlCu2Mn-type Structure Research Articles

Investigation of half-metallic properties of full-Heusler alloys of O2BaX (X = Na,K, Rb, and Cs)

Calculations were performed based on first principles and density functional theory using the full-potential linearized augmented plane wave (FPLAPW) to investigate the structural, electronic, and magnetic properties of Heusler compounds of O2BaX (X = Na, K, Rb, and Cs). The results showed that the ground state of four compounds was the AlCu2Mn-type structure in the ferromagnetic state. It was predicted that O2BaX (X = Na, K, Rb, and Cs) compounds were ferromagnetic half-metals in both AlCu2Mn-type and CuHg2Ti-type phases. The origin of the half-metallicity was also studied using electronic density of states (DOSs). These alloys were half-metals 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 of O2BaX (X = Na, K, Rb, and Cs) compounds were obtained 1 μB per formula unit at the equilibrium lattice parameter, which were in agreement with Slater–Pauling rule Mtot=(12-Ztot)μB. The observed results confirm the suitability of O2BaX (X = Na, K, Rb, and Cs) compounds in spintronics applications.

First-principles calculations to investigate electronic, magnetic and half-metallic ferromagnetic properties of full-Heusler Mn2OsSn

ABSTRACT The structural, electrical, magnetic, and elastic characteristics of the Mn2OsSn full-Heusler compound have all been studied using the full potential linearised augmented plane (FP-LAPW) method. The study's exchange and correlation potentials are calculated using the generalised gradient approach (GGA) developed by Burke, Perdew, and Ernzerhof; the GGA with the Tran-Blaha-modified Becke–Johnson approximations; and the GGA with the correlated Hubbard parameter (GGA +U). Our calculations show that the formation energy of the compound is negative for the two-type structure, which means the crystal may persist indefinitely. Our chemical has a convex hull distance at 0 K for cubic regular and inverse-type structures, indicating that it will likely be synthesised via equilibrium processing. The electronic band structures, densities of states, and 100 spin-polarisation at the Fermi level in the typical cubic AlCu2Mn-type structure show Mn2OsSn in its complete Heusler ferromagnetic state has a half-metallic feature with an indirect band gap in the minority spin. Alternatively, in the CuHg2Ti-type ferromagnetic state, with its inverse cubic structure, this material exhibits metallic ferromagnetic behaviour with a polarisation of 96,325. The half metallicity of the AlCu2Mn-type combination is preserved at 1 GPa of hydrostatic pressure. Thus, Mn2OsSn, with the appropriate correction option for the Hubbard-Coulomb parameter U, will be a promising contender for spintronic applications.

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.

Effect of 5d state-based full-Heusler alloys on the structural, electronic and magnetic properties of new half metallic ferromagnetism

First-principles calculations of structural, elastic, electronic and magnetic properties of full-Heusler Ir2HfB, Ir2HfAl and Ir2HfGa have been realized by full-potential linearized augmented plane wave (FP-LAPW) method implemented inWIEN2K code. The Perdew–Burke–Ernzerh of generalized gradient approximation (PBE-GGA) carried out the computation of different parameters to describe elastic and structural properties. The calculation of structural properties revealed that the three alloys are stable in cubic AlCu2Mn-type structure in ferromagnetic state. The elastic constants calculation shows the three alloys satisfy the stability criteria. Indeed, the calculated spin-polarized electronic band structure and density of states using generalized gradient approximation (GGA) show that Ir2HfZ (Z = B, Al, Ga) alloys have a metallic character. The influence of strong electronic correlation has been considered in GGA+Uand mBJ-GGA+U approximations that allows for improving the width of the band gap. The calculations carried out with GGA+U and mBJ-GGA+U show that Ir2HfAl and Ir2HfGa have a half-metallic behavior; however, Ir2HfB has a near half-metallic character. The calculated magnetic moments of Ir2HfB, Ir2HfAl and Ir2HfGa in a regular cubic structure with GGA+U and mBJ-GGA+U equal 1μB. With mBJ-GGA+U, the spin polarization values are 100% for Ir2HfAl, Ir2HfGa and 99.90% for Ir2HfBto be applicable for spintronics.

First-principles study of electronic structures, thermodynamic, and thermoelectric properties of the new Rattling Full Heusler compounds Ba2AgZ (Z = As, Sb, Bi)

The ab initio calculations based on the density functional theory (DFT) using the self-consistent Full potential linearized augmented plane wave (FPLAPW) method were performed to explore the electronic structures, thermodynamic and thermoelectric properties of new rattling Full Heusler alloys Ba2AgZ (Z = As, Sb, Bi). Results showed that the AlCu2Mn-type structure state is energetically the most stable structure. The results show that the electronic property of these cubic Rattling Heusler alloys have a semiconducting behavior with indirect band gaps Eg (L-D). The predicted band gaps were found to be 0.566, 0.548 and 0.433 eV for Z = As, Sb and Bi, respectively. The thermodynamic properties comprising the thermal expansion coefficient, heat capacity, entropy and Debye temperature parameter were evaluated at various pressures from 0 to 15 GPa. Thermoelectric properties of the Ba2AgZ (Z= As, Sb, Bi) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds exhibit ultralow thermal conductivity, good Seebeck coefficients and large high power factors, thus resulting they are suitable for use in thermoelectric device applications.

A comparative study of structural electronic and magnetic properties of full-Heuslers Co2MnZ (Z=Al, Ge and Sn)

Ab initio calculations of structural, electronic and magnetic properties of full-Heuslers Co2MnAl, Co2MnGe and Co2MnSn, were accomplished successfully alloys by full-potential linearized augmented planewave (FP-LAPW) of density of state (DFT). By applying the generalized gradient Approximation (GGA)- Perdew-Burke-Ernzerhof (PBE) and modified Becke-Johnson (mBJ), we found that structural optimizations confirm the stability of this Heusler in Fm3¯m phase. Volume optimization in ferromagnetic and non-magnetic phases for the AlCu2Mn-type (L21) structure was done to predict the stable ground state configuration. Half-metallic character is observed via density of state calculations and band structure analysis and together with spin magnetic moments. Band gap of our system has been deduced by two methods. The obtained results are comparable with other theoretical and experimental results.

Half-Metallic Characteristic in the New Full–Heusler SrYO2 (Y = Sc, Ti, V, and Cr)

Half-metallic properties of SrYO2 (Y = Sc, Ti, V, and Cr) full-Hensler compounds were studied using full-potential linearized augmented plane wave method based on density functional theory. The negative formation energies of SrYO2 (Y = Sc, Ti, V, and Cr) alloys confirmed that they can be synthesized experimentally. Total energy calculations showed that AlCu2Mn-type structure was the ground state structure in all compounds. In both structures, SrYO2 (Y = Ti, V, and Cr) alloys were half-metallic ferrromagnets, while SrScO2 was a non- magnetic metal. The origin of half-metallicity was verified for SrCrO2. SrYO2 (Y = Ti, V, and Cr) alloys in both structures were half-metals in a wide range of lattice constants indicating that they are quite robust against hydrostatic strains. The magnetization of SrYO2 (Y = Ti, V, and Cr) alloys was mainly originated from the 3d electrons of Y (= Ti, V, and Cr) atoms and followed the Slater–Pauling rule: Mtot = Ztot – 12. Generally, It is expected that SrYO2 (Y = Ti, V, and Cr) alloys are promising and interesting candidates in the future spintronic field.

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.

Half-metallicity in new Heusler alloys NaTO2 (T=Sc, Ti, V, Cr, and Mn): A first-principles study

On the basis of the full-potential linearized augmented plane wave (FPLAPW) method within density functional theory (DFT), electronic structure and magnetic properties of Heusler alloys NaTO2 (T = Sc, Ti, V, Cr, and Mn) were investigated. The negative values of formation energy showed that these compounds can be experimentally synthesized. Results showed that in all compounds, AlCu2Mn-type structure was the most favorable one. The NaTO2 (T = Sc, Ti, V, Cr, and Mn) alloys were HM ferromagnets except NaScO2 (in both structures which were nonmagnetic semiconductors) and NaVO2 (in AlCu2Mn-type structure which was a magnetic semiconductor). The origin of half-metallicity was also verified in HM alloys. NaCrO2 and NaVO2 alloys had higher half-metallic band gaps in comparison with Heusler alloys including and excluding transition metals. The total magnetic moments of HM NaTO2 (T = Ti, V, Cr, and Mn) alloys obeyed Slater-Pauling rule (Mtot = Ztot-12). Among NaTO2 (T = Sc, Ti, V, Cr, and Mn) alloys, NaCrO2 had the highest robustness of half-metallicity with variation of lattice constant in both structures.

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.

Ab-initio study of mechanical, half-metallic and optical properties of Mn2ZrX (X = Ge, Si) compounds

The structural, elastic, electronic, magnetic and optical properties of Mn2 based full-Heusler alloys, Mn2ZrGe and Mn2ZrSi, were investigated by the first-principles full-potential linearized augmented plane wave (FP-LAPW) method in the framework of the Density Functional Theory. The AlCu2Mn-type structure was considered for both compounds. Based on E-V calculation, the ferromagnetic (FM) state was more stable than paramagnetic (PM) state. So, in the FM state the equilibrium lattice parameter was calculated as 5.995Å and 6.079Å for Mn2ZrSi and Mn2ZrGe respectively. The integer value 2.000µB is obtained for total magnetic moments of both compounds that is perfectly consistent with Slater-Pauling rule. These alloys in the minority spin channel have metallic property while in the majority spin channel, they have band gap that confirms their semiconductor properties. Elastic properties of the alloys such as bulk modulus B, shear modulus G, Young’s modulus E and Poisson's modulus ν were obtained. Also, optical properties like dielectric function, reflectivity, energy loss function, absorption coefficient and optical conductivity were calculated.

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.

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.

Electronic Structure and Magnetism of Ti2(Pd, Pt) (B, Al, Ga, In): A First-Principle Study

Within the framework of density functional theory, the electronic structure and magnetic properties have been studied for Ti2(Pd, Pt)(B, Al, Ga and In) Full Heusler alloys within AlCu2Mn and Hg2CuTi-type structures for both ferromagnetic and paramagnetic cases. The investigation was done using the (FP-LAPW) method where the exchange-correlation potential was calculated with the frame of GGA (Perdew et al, Phys. Rev. Lett. 77 (1996) 3865). Results showed that Ti2PdAl, Ti2PdIn, Ti2PtAl, Ti2PtGa, and Ti2PtIn alloys are HM ferromagnets with a magnetic moment of 3 μ B per formula unit which were in agreement with Slater–Pauling rule m tot = N v-18. In addition, the energy band gap decreases with increasing atomic number Z in the Hg2CuTi-type structure. These new materials are good candidates for potential applications in spintronic. The Ti2PdGa, Ti2PdB and Ti2PtB alloys in the AlCu2Mn-type structure are found to be energetically more favorable than Hg2CuTi-type structure The highest spin-polarization at Fermi energy 45, 42, and 18 % is expected for Ti2PdGa, Ti2PdB and Ti2PtB, respectively.

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.