Spin-polarized Electronic Band Structure Research Articles

Magneto-optical properties of heavily Fe-doped GaAs: a density functional approach.

The magneto-optical properties of heavily iron-doped GaAs are investigated. Complex permittivity, optical conductivity and absorption coefficients are mainly discussed using spin-polarized electronic band structures close to the Fermi energy level. Furthermore, prominent magneto-optical properties in visible light and ultraviolet regions, including magnetic circular dichroism as well as complex Kerr and Faraday rotation angles, are presented and discussed. A density functional approach corroborated by some experimental results indicates that GaAs with 25% Fe dopants either in As or Ga sites is a promising ferromagnetic material and a useful platform for optoelectronic and spintronic device applications.

First Principles Calculations of Novel Binary Transition Metal Oxides NaCr0.5X0.5O2 (X = Y, Tc, Rh) for Na-Ion Batteries

Recently, layered transition metal oxides have demonstrated voltage windows favorable for use as cathodes in sodium-ion batteries, leading to increased specific capacity and energy density. Here, NaCr0.5Y0.5O2, NaCr0.5Tc0.5O2, and NaCr0.5Rh0.5O2 were studied by using first-principles calculations to elucidate their properties. There is a trigonal arrangement in the structure of both pure and substituted NaCrO2. Structural characteristics reveal the ferromagnetic behavior of these compounds (NaCr0.5X0.5O2; X = Y, Tc, Rh). We calculated the density of states and spin-polarized electronic band structures for the three compounds tested. NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2 exhibit diluted magnetic semiconductor (DMS) behavior, while NaCr0.5Tc0.5O2 has half-metallic (HM) behavior. The substitutional material’s ferromagnetic nature is confirmed by the negative values of the exchange constants (Nօ α and Nօ β). The fractional value of the magnetic moment also confirms the DMS nature of NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2, while the HM behavior is confirmed by the integral value of the magnetic moment for NaCr0.5Tc0.5O2. The thermoelectric characteristics were computed using the BoltzTraP code. Alectrochemical analysis of NaCr0.5Y0.5O2 showed a theoretical discharge capacity of 400 mhAg−1 and an average intercalation voltage of 4.87 V, calculated from the total energies of the optimized compounds and their de-sodianted phases. These theoretical computations demonstrate that the binary layered TM oxides studied are appropriate substances to employ in coin cell fabrication as cathodes.

Iron-arsenide monolayers as an anode material for lithium-ion batteries: a first-principles study.

This theoretical investigation delves into the structural, electronic, and electrochemical properties of two hexagonal iron-arsenide monolayers, 1T-FeAs and 1H-FeAs, focusing on their potential as anode materials for lithium-ion batteries. Previous studies have highlighted the ferromagnetic nature of 1T-FeAs at room temperature. Our calculations reveal that both phases exhibit metallic behaviour with spin-polarized electronic band structures. Electrochemical studies show that the 1T-FeAs monolayer has better ionic conductivity for Li ions than the 1H-FeAs phase, attributed to a lower activation barrier of 0.38 eV. This characteristic suggests a faster charge/discharge rate. Both FeAs phases exhibit comparable theoretical capacities (374 mA h g-1), outperforming commercial graphite anodes. The average open-circuit voltage for maximum Li atom adsorption is 0.61 V for 1H-FeAs and 0.44 V for 1T-FeAs. The volume expansion over the maximum adsorption of Li atoms on both phases is also remarkably less than the commercially used anode material such as graphite. Furthermore, the adsorption of Li atoms onto 1H-FeAs induces a remarkable transition from ferromagnetism to anti-ferromagnetism, with minimal impact on the electronic band structure. In contrast, the original state of 1T-FeAs remains unaffected by Li adsorption. To summarize, both 1T-FeAs and 1H-FeAs monolayers have potential as promising anode materials for lithium-ion batteries, offering valuable insights into their electrochemical performance and phase transition behaviour upon Li adsorption.

Theoretical study of adsorption properties and electrical transport performance of toxic gas molecules on novel orthorhombic BN monolayer semiconductor

The adsorption properties of toxic gases on the surface of low-dimensional nanomaterials are a research hot topic and key issue for developing semiconductor sensors to detect toxic gas molecules. Recently, a novel orthorhombic BN monolayer has attracted extensive attention from researchers. Using first principles calculations, we investigate the adsorption properties of typical toxic gas molecules, such as CO, H<sub>2</sub>S, NH<sub>3</sub>, NO, NO<sub>2</sub>, and SO<sub>2</sub> molecules, on the surface of two-dimensional (2D) orthorhombic BN monolayer adsorption. The calculated adsorption energy show that the adsorptions of the above six molecules on the surface of BN monolayer are energy-favorable exothermic processes. It is found that NO<sub>2</sub> and NH<sub>3</sub> molecules are of chemical adsorption, while other systems are of physical adsorption, and NO adsorbing system exhibits a spin-polarized electronic band structure. The calculated density of states reveals that the adsorption of NO molecule and SO<sub>2</sub> molecule have significant influences on the electronic structure near the Fermi level. Moreover, the adsorption of the NO<sub>2</sub> molecule on the substrate exhibits remarkable variation of the work function, suggesting that the o-BN monolayer possesses excellent selectivity and sensitivity to NO<sub>2</sub> molecule. In addition, we use first principles combined with non-equilibrium Green’s function to simulate the electrical transport properties of monolayered o-BN semiconductor based nanodevice with adsorption of typical toxic gas molecules. The <i>I-V</i><sub>b</sub> curve shows that the current through the nanodevice is 6500 nA for the NO<sub>2</sub> molecule adsorbing system under 1 V bias voltage. The calculation results reveal that the adsorption of NO<sub>2</sub> molecule on the o-BN monolayer can significantly enhance its electrical transport performance, and the o-BN monolayer possesses excellent sensitivity and selectivity to the NO<sub>2</sub> gas molecule. The work function and the charge transfer can be effectively manipulated by tensile strain, indicating its potential application in anisotropic electronics. Our results indicate that the o-BN monolayer has excellent adsorption performance to toxic gases, showing its practical application in capturing toxic gas molecules as a gas sensor in future.

First-principles calculations to investigate structural, electronic, optical and thermoelectric properties of novel double perovskite Cs2CeAgX6 (X = Cl, Br) for optoelectronic and thermoelectric applications

The present study unveils physical characteristics, including elastic parameters, phonon dispersion, electronics, optical, and thermoelectrics behavior’s novel double perovskite Cs2CeAgX6(X = Cl, Br) by performing FP-LAPW computational approach. The mechanical stability of studied compounds has been addressed rigorously, and both compounds are ductile, revealing their potential for the fabrication of optoelectronic and thermal devices. Moreover, the phonon dispersion advocated about dynamical stability of the Cs2CeAgX6(X = Cl, Br) compounds. Both studied compounds have shown a wider band gap, a clear signature of a semiconductor nature. Spin-polarized electronicband structure's outcomes as well as electronic density of states have been computed using TB-mBJ approximation.Moreover, Cs2CeAgBr6 offers a reduced gap rather then Cs2CeAgCl6. The photo response analysis shows that Cs2CeAgBr6 can absorb various ultraviolet (UV) and visible electromagnetic radiations. Henceforth, Cs2CeAgBr6 is found to be a more suitable aspirant for optoelectronic device fabrication. Regarding composites' thermoelectric behaviour, the Seebeck coefficient reflects that studied materials are hole-based semiconductors computed by the BoltzTrap code. Cs2CeAgCl6 has shown a higher thermal conductivity magnitude than Cs2CeAgBr6, so It's a potential thermoelectric material devices and allied applications.

Optical and magnetic characteristics of BaTi1-xCoxO3: A first-principles study

The full potential linearized augmented plane wave (FP-LAPW) approach based on the density functional theory (DFT) is employed to know the effect of Co doping on the electronic, optical, and magnetic characteristics of BaTi1-xCoxO3 at x= 8.33%, 16.66%, 25%, and 50%. The computed spin-polarized electronic band structure (BS) and the density of states (DOS) elucidate that the BaTi1-xCoxO3 compound has a ferromagnetic semiconductor behavior at all doping concentrations. The results indicate that the magnetic moment in BaTi1-xCoxO3 is found due to the p-d hybrid orbitals of Co. Moreover, the optical features of the Co-doped BTO compound are evaluated by analyzing the refractive index, reflectivity, absorption coefficient, optical conductivity, and dielectric constant under different concentrations. The outcomes revealed that the BaTi1-xCoxO3 compound is a good candidate for spintronics and optoelectronic applications.

Electronic, optical and magnetic properties of Gd2FeCrO6 double perovskite using DFT

The double perovskite oxide materials have enormous applications in electronics, solid oxide fuel cells, photochemistry, magnetocaloric devices, optical technologies, etc. In this paper, we calculated spin-polarized electronic band structure, optical properties, magnetic moments and density of states of Gd2FeCrO6 (GFCO) by applying generalized gradient approximation (GGA) and GGA + U theories. The energy bands in spin-up and down channels are reported corresponding to Hubbard parameter, Ueff = 2 and 4 eV applied on Fe and Cr-3d orbitals within GGA + U approach to examine the influence of on-site Coulomb interaction energy on various physical properties of GFCO. In contrast to GGA theory, wherein a small band gap was observed, the GGA + U computations resulted in enhanced band gap values in both channels in accordance with earlier reported literature. The dielectric function, refractive index, absorption coefficient and energy loss functions are calculated. The magnetic moments are also calculated by using GGA and GGA + U theories.

Magnetocrystalline anisotropy energy and Gilbert damping of two-dimensional half-metallic RhX2 (X = I, Br, Cl) ferromagnets: Density functional theory study

This work studies the monolayer rhodium dihalides family, RhX2 (where X = I, Br, Cl), using density functional theory. We first calculate the spin-polarized electronic band structure, revealing a wide intrinsic half-metallic gap (>1.1 eV) in the down spin bands of RhX2 monolayers. We then calculate the magnetocrystalline anisotropy energy (EMCA) and Gilbert damping (α), which originate from the spin–orbit coupling (SOC) phenomenon. We use the force theorem for EMCA calculation that results in substantial in-plane anisotropy in RhI2 (−2.31 meV/unit cell) and RhBr2 (−0.52 meV/unit cell), whereas small perpendicular anisotropy in RhCl2 (0.04 meV/unit cell) monolayers. To calculate α, we employ the Kambersky’s torque–torque correlation model and it comes out relatively low (i.e., 0.0212, 0.0079, and 0.0040 for RhI2, RhBr2, and RhCl2, respectively). The Curie temperature of these crystals is calculated using the Ising model and spin-wave theory. This work highlights the importance of 2D RhX2 half-metallic ferromagnets in the fabrication of future nanoscale spintronic devices.

Electronic Behavior and Optical Properties of New Ferromagnetic Silver-Based Sulfo-spinel: AgV2S4

This study reports the intriguing properties of a novel ternary silver-based sulfo-spinel vanadium system (AgV2S4) having a face centered cubic structure (FCC). The magnetic nature, electronic behavior and optical properties of this system are revealed. The calculations were performed with spin-effect and by using generalized gradient approximation (GGA) under Density Functional Theory (DFT). After obtaining the optimized Wyckoff positions for the atoms in the crystal structure of this composition, it was decided that this spinel material has ferromagnetic nature in view of the energy-volume curves obtained for three different magnetic phases and of the calculated cohesive energies. Furthermore, the spin-polarized electronic band structure with the orbital projected density of electronic states was calculated within first principles to investigate its electronic behavior and bonding characteristic in detail. The observed small band gap in minority spin channel is Eg = 0.41 eV, so its electronic band structure imply that this system has half-metallic character. Finally, to evaluate some optical features, frequency dependent complex dielectric functions were calculated. Then, some optical properties were investigated by using the real and imaginary parts of the dielectric function.

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 studies of the elastic and magnetic properties of monolayer CrN

Two-dimensional (2D) materials with robust ferromagnetism properties have high potentials for application in the field of spintronics. However, extensively pursued 2D sheets, including pure graphene, monolayer BN, and layered transition metal dichalcogenides, are either nonmagnetic or weakly magnetic. The elastic, electronic and magnetic properties of monolayer CrN are calculated using the plane wave pseudo potential method based on first-principles density function theory. Upon determining through calculation that the structure of the monolayer CrN nanosheet is stable, its layer modulus [Formula: see text] shows that its strain resistance is stronger than that of graphene. Through strain analysis, materials with a monolayer CrN type of structure can be obtained. It is determined that 10% of the change in equilibrium area is still applicable to the 2D EOS, showing that this structure is quite stable. The spin-polarized electronic band structure is also calculated under different plane symmetry strains. The plane strain can be used to effectively adjust the metallic and magnetic properties of the material. Analyses of the band structure and density of states reveal that this material is half-metallic, where the origin of the ferromagnetism is related to [Formula: see text]–[Formula: see text] exchange interactions between the Cr and N atoms. Monolayer CrN has semimetallic properties and strong ferromagnetic (FM) properties. The FM effect can enhance the stability of the material. The results show that monolayer CrN is a semimetallic material with good elastic properties and a strong FM property. This material is therefore expected to have good application rospects in the field of spin electronics.

First-principles calculation of the electronic and optical properties of Gd2FeCrO6 double perovskite: Effect of Hubbard U parameter

We have synthesized Gd$_{2}$FeCrO$_{6}$ (GFCO) double perovskite which is crystallized in a monoclinic structure with P2$_{1}/$n space group. The UV-visible and photoluminescence spectroscopic analyses confirmed its direct bandgap semiconducting nature. Employing experimentally obtained structural parameters in first-principles calculation, we report the spin-polarized electronic band structure, charge carrier effective mass, density of states, electronic charge density distribution and optical absorption property of the GFCO double perovskite. The effects of on-site d-d Coulomb interaction energy (U$_{eff}$) on the electronic and optical properties were investigated by applying a range of Hubbard U$_{eff}$ parameters from 0 to 6 eV to the Fe-3d and Cr-3d orbitals within the generalized gradient approximation (GGA) and GGA+U methods. When we applied U$_{eff}$ in the range of 1 to 5 eV, both the up-spin and down-spin band structures were observed to be direct. The charge carrier effective masses were also found to enhance gradually from U$_{eff} =$ 1 eV to 5 eV, but, these values were anomalous for U$_{eff} =$ 0 and 6 eV. These results suggest that U$_{eff}$ should be limited within the range of 1 to 5 eV to calculate the structural, electronic and optical properties of GFCO double perovskite. We observed that considering U$_{eff} =$ 3 eV, the theoretically calculated optical band gap 1.99 eV matched well with the experimentally obtained value 2.0 eV. The outcomes of our finding imply that the U$_{eff}$ value of 3 eV most accurately localized the Fe-3d and Cr-3d orbitals of GFCO keeping the effect of self-interaction error from the other orbitals almost negligible. Therefore, we may recommend U$_{eff} =$ 3 eV for first-principles calculation of the electronic and optical properties of GFCO double perovskite that might have potential in photocatalytic and related solar energy applications.

First-principles calculations to investigate electronic structure and magnetic, mechanical and thermodynamic properties of d0 half-Heusler LiXN (X= Na, K, Rb) alloys

Density functional theory (DFT) incorporating GGA-PBE approximation has been implemented to study structural, electronic, magnetic, mechanical and thermodynamic properties of the d0 Half-Heusler LiXN (X = Na, K, Rb) alloys. According to the spin-polarized calculations, all the LiXN alloys crystallize in the α-phase ferromagnetic ground state configuration. All three LiXN alloys show a total magnetic moment of 1.00 μB. The integer values of the total magnetic moments, along with the spin-polarized electronic band structures and the density of states plots indicate that the LiXN alloys are true half-metals in nature. The half-metallic nature of the LiXN alloys is further confirmed as the total magnetic moments are in complete agreement with the Slater-Pauling rule of 8. The origin of the half-metallic ferromagnetic behaviour has been investigated and it has been observed that the 2p states of N are the major contributors in case of all the three alloys. The alloys retain the characteristic half-metallicity over a wide range of lattice parameters, thus confirming their robustness and usability in a variety of spintronic applications. The mechanical properties of the LiXN alloys have been investigated and it has been observed that LiKN and LiRbN are found to be mechanically unstable, whereas LiNaN is chemically, energetically and mechanically stable. Various thermodynamic properties have been further computed and analysed using the quasi-harmonic approximation (QHA). Specific heat capacity at room temperature (300K), the Debye temperature, and the zero-point energy for the LiNaN alloy as well as the average velocity of sound inside the LiNaN alloy have been evaluated.

Physical properties of Mn- and Fe-doped CaS: A DFT insights

In the present paper, we investigate the structural, electronic magnetic and elastic properties of ordered dilute ferromagnetic semiconductors Ca0.75Mn0.25S and Ca0.75Fe0.25S using the full-potential linearized augmented plane-wave (FP-LAPW) method. We adopt the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), GGA-PBE + U and the modified Becke-Johnson exchange potential for the exchange-correlation energy and potential. The spin-polarized electronic band structures and density of states of Ca0.75Fe0.25S calculated by GGA-PBE, mBJ-GGA-PBE and GGA-PBE + U show that the minority spin channel has metallic nature and the majority spin channel has a half-metallic gap of 0.74,0.78 and 0.54 eV, respectively. For Ca0.75Mn0.25S the band structures calculated within GGA-PBE and mBJ-GGA-PBE shows a half-metallic behavior, whereas when we use the GGA-PBE + U, we see that this compound is semiconductor with magnetic moment of 5 μB per formula unit. Moreover, the elastic constants, bulk modulus, shear modulus, and universal elastic anisotropy are calculated, which have not been measured yet. Analysis of elastic constants demonstrated that both Ca0.75Mn0.25S and Ca0.75Fe0.25S are mechanically stable.

First principle insight on physical characteristics of Mn doped BeS compound

The electronic, optical and magnetic properties of Be1-xMnxS (x = 3.125%, 6.25%, 12.5% and 18.75%) semiconductors have been performed by PBEsol + GGA approximations. The investigation was done by using full potential-linearized augmented plane wave (FP-LAPW) method with in DFT as implemented in the WIEN2K code. Stability of Be1-xMnxS compounds is confirmed by the heat of enthalpy formation. In electronic properties, the spin-polarized electronic band structure and density of states elucidate the semiconductor nature of material in both spin channels at different concentration of dopant atoms. The nature and origin of ferromagnetism have been observed in term of crystal-field energies, exchange constant and the exchange energies. Optical parameters like extinction coefficient, refractive index, dielectric constant, reflectivity, optical conductivity and absorption coefficient are analyzed which active in visible to ultraviolet region. The refractive index less than unity illustrate that the group velocity of the incident photons is greater than the speed of light. Furthermore, the total magnetic moment of Be1-xMnxS alloys is mainly due to the Mn site with very small contribution of Be and S and increases with increasingconcentration of Mn. Calculated results indicate that the electronic, magnetic and optical properties provide a new route to the experimentalist for the potential applications in optoelectronic and spintronics devices.

Ab-initio computations of CaV2S4 and CaMn2S4 spinels for spintronics and energy storage system applications

Having ferromagnetism capabilities and energy storage capacity, CaV2S4 and CaMn2S4 spinels are interesting materials owing to their potential applications in spintronics applications. In the present study, the half-metallic ferromagnetic nature and the electronic transport properties of CaV2S4 and CaMn2S4 has been explored using density functional theory computations. The ground-state energies of these spinels have been computed through volume optimization of non-magnetic (NM), ferromagnetic (FM) and anti-ferromagnetic (AFM) phases, which show FM phase to be stable for both the studied spinels. In additions, the lattice parameters calculated for the FM phase show good comparison with existing theoretical data. For the investigation of the magnetic and electronic structure properties, we have used the modified Becke-Johnson (mBJ) potential functional. The density of state (DOS) plots and spin-polarized electronic band structures (BS) confirm half-metallic behavior of the studies spinels. Further, to reveal the magnetic nature of studied spinels, we have also calculated crystal field splitting and exchange energies. Occurrence of strong p-d hybridization arising from V/Mn 3dt2g-states and S p-states is confirmed which is also evident from the fact that total sum of magnetic moment proved to be lower than the estimated values. In addition, the influence of electron spin on transport properties of the CaV2S4 and CaMn2S4 has also been examined using the Boltzmann transport theory.

Study of Half Metallic Ferromagnetism and Optical Properties of Mn-Doped CdS

The spin-polarized electronic band structures, density of states and optical and magnetic properties of dilute magnetic semiconductors (DMSs) Cd1−xMnxS with 6.25%, 12.5% and 25% concentrations of Mn have been studied by using ab initio calculations. The electronic band structures show half metallic ferromagnetic (HMF) behaviour with direct band gap at Γ symmetry point. The calculated values of band gaps are 0.8 eV, 0.99 eV, 1.3 eV and 1.5 eV for CdS, Cd0.9375Mn0.0625S, Cd0.875Mn0.1250S and Cd0.75Mn0.25S, respectively. The energy gap of CdS was found to increase by doping with transition metal impurity. The addition of the dopant atoms in CdS turns it into a p-type semiconductor. This half metallic character makes these compounds a potential candidate for spintronics applications. In optical properties, the role of Mn concentration on the absorption coefficient, optical conductivity, refractive index, extinction coefficient and dielectric function has been investigated. The total magnetic moment is found approximately 5.000 μB per dopant atom for Cd1−xMnxS (x = 6.25%, 12.5% and 25%). This value indicates that every Mn impurity adds no hole carriers to the perfect CdS crystal.

First-Principles Study of the New Half-Metallic Ferromagnetic Quaternary-Heusler Alloys NaXNO (X=Ca, Sr, Ba)

The first-principles approach based on density functional theory (DFT) and the full-potential linearized augmented plane-wave method were employed to investigate the structural, elastic, electronic and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. The generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE) and the modified Becke–Johnson exchange potential were used. As far as we know, we present our results which for the first time quantitatively account for the electronic structures and magnetic properties of Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys. From the total energy calculation using three possible atomic configurations ([Formula: see text], [Formula: see text] and [Formula: see text]), it is found that the Na[Formula: see text]NO ([Formula: see text], Sr and Ba) quaternary half-Heusler alloys are more stable in the ferromagnetic [Formula: see text]-phase. From our estimated elastic constants [Formula: see text], it is found that all the considered Heusler alloys are mechanically stable in the [Formula: see text]-phase. We have also investigated the robustness of the half-metallicity with respect to the variation of lattice constants in these alloys. We have found that these alloys are half-metallic ferromagnets (HMFs) with a magnetic moment of 2[Formula: see text][Formula: see text] per formula unit at their equilibrium volumes. The spin-polarized electronic band structure and density of states of these quaternary half-Heusler alloys calculated by GGA (mBJ-GGA) show that the minority spin channels have metallic nature and the majority spin channels have a semiconductor character with half-metallic gaps of 0.49[Formula: see text]eV (2.17[Formula: see text]eV), 0.72[Formula: see text]eV (2.28[Formula: see text]eV) and 0.96[Formula: see text]eV (2.22[Formula: see text]eV) for NaCaNO, NaSrNO and NaBaNO quaternary half-Heusler alloys, respectively. Analysis of the density of states and the spin charge density of these quaternary alloys indicates that their magnetic moments mainly originate from the strong spin-polarization of 2[Formula: see text] states of N atoms and O atoms.

Fe3Se4: a possible ferrimagnetic half-metal?

Half-metallic ferromagnets show 100% spin-polarization at the Fermi level and are ideal candidates for spintronic applications. Despite the extensive research in the field, very few materials have been discovered so far. Here, we present results of electronic band structure calculations based on density functional theory and extensive physical-property measurements for Fe3Se4 revealing signatures of half-metallicity. The spin-polarized electronic band structure calculations predict half-metallic ferrimagnetism for Fe3Se4. The electrical resistivity follows exponentially suppressed electron–magnon scattering mechanism in the low-temperature regime and show a magnetoresistance effect that changes the sign from negative to positive with decreasing temperature around 100 K. Other intriguing observations include the anomalous behavior of Hall resistance below 100 K and an anomalous Hall coefficient that roughly follows the ρ2 behavior.

D0 Half-Metallic Ferromagnetism in GeNaZ (Z = Ca, Sr, and Ba) Ternary Half-Heusler Alloys: an Ab initio Investigation

First-principles approach based on density functional theory was applied to investigate the structural, elastic, phonon dynamics, thermodynamics, electronic, and magnetic properties of GeNaZ (where Z = Ca, Sr and Ba) ternary Heusler alloys. The Perdew-Burke-Ernzerhof generalized gradient approximation (GGA) and the modified Becke-Johnson (mBJ-GGA) were used for the exchange-correlation energy and potential. The GeNaZ ternary Heusler alloys were found to be half-metallic and stable in the ferromagnetic α phase. The alloys were found to satisfy the criteria for dynamic and elastic stabilities. Thus, they are dynamically and elastically stable. The calculated spin-polarized electronic band structure and density of states using GGA (mBJ-GGA) reveal that the minority spin channel has metallic character and the majority spin channel having an electronic band gap of 0.26 (0.59), 0.39 (0.66), and 0.08 (0.33) eV for the GeNaCa, GeNaSr, and GeNaBa ternary Heusler alloys, respectively. The considered alloys all result in a stable ferromagnetic half-metallic ground state structure with a magnetic moment of 1 μB/cell. The density of states and the spin-charge density of these alloys show that the magnetization originates primarily from the 4p states of the Ge atoms. The GeNaZ ternary Heusler alloys do not have any magnetic elements, and their induced magnetism makes them very promising materials for spintronic devices.