Half-metal Research Articles

Structural stabilities and natural half-metallic properties of OsXCoSi (X=Ti, Zr, Hf) quaternary Heusler alloys series first-principles calculations

Based on first-principles calculation of density functional theory, this study investigates the structural stability, magnetic properties, and electronic properties of the three different phases (i.e. type 1, type 2, and type 3) of OsXCoSi (X=Ti, Zr, Hf) in a new quaternary Heusler alloy series. The corresponding equilibrium lattice constants of each type are optimized, and the change of formation enthalpy and elastic constant phonon spectrum show that the OsXCoSi (X=Ti, Zr, Hf) alloy is thermodynamically, dynamically and mechanically stable. Furthermore, the bonding features of each phase are discussed. It is found that all type 1 structures of OsXCoSi (X=Ti, Zr, Hf) exhibit natural half-metallicity (HM) in equilibrium lattice constant, and their equilibrium lattice constants in the ground state were determined to be 5.909 Å for OsTiCoSi, 6.155 Å for OsZrCoSi, and 6.100 Å for OsHfCoSi. Meanwhile, by testing the alloy under different pressures, the range of the integer magnetic moment non-equilibrium lattice constants for the three alloys OsTiCoSi, OsZrCoSi, and OsHfCoSi are 5.710 Å ∼ 6.329 Å, 5.696 Å ∼ 6.1557 Å and 5.716 Å ∼6.1009 Å, respectively, which is wide and is more close to the practical application for spin-polarized materials. In addition, its magnetic moment is consistent with the values given by the Slater–Pauling rule. Furthermore, the forming of the HM gap is examined by analysing the total and partial density of states, energy bands of alloy’s electronic property, with respect to the calculated results. What’s more, special attention is paid to the differences of the properties for series Heusler alloys. It is found that the electronics properties distinction is mainly based on valence electron changes. However, the lattice constants are susceptible to size of a nucleus.

Rational design and synthesis of Cr1–x Te/Ag2Te composites for solid-state thermoelectromagnetic cooling near room temperature

Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic cooling. These two properties, however, hardly coexist in single phase materials except previously reported hexagonal Cr1−x Te half metal where a relatively high magnetic entropy change (−ΔS M) of ∼2.4 J⋅kg−1⋅K−1 @ 5 T and a moderate thermoelectric figure of merit (ZT) of ∼1.2 × 10−2@ 300 K are simultaneously recorded. Herein we aim to increase the thermoelectric performance of Cr1−x Te by compositing with semiconducting Ag2Te. It is discovered that the in-situ synthesis of Cr1−x Te/Ag2Te composites by reacting their constitute elements above melting temperatures is unsuccessful because of strong phase competition. Specifically, at elevated temperatures (T > 800 K), Cr1−x Te has a much lower deformation energy than Ag2Te and tends to become more Cr-deficient by capturing Te from Ag2Te. Therefore, Ag is insufficiently reacted and as a metal it deteriorates ZT. We then rationalize the synthesis of Cr1−x Te/Ag2Te composites by ex-situ mix of the pre-prepared Cr1−x Te and Ag2Te binary compounds followed by densification at a low sintering temperature of 573 K under a pressure of 3.5 GPa. We show that by compositing with 7 mol% Ag2Te, the Seebeck coefficient of Cr1−x Te is largely increased while the lattice thermal conductivity is considerably reduced, leading to 72% improvement of ZT. By comparison, −ΔS M is only slightly reduced by 10% in the composite. Our work demonstrates the potential of Cr1−x Te/Ag2Te composites for thermoelectromagnetic cooling.

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.

Exploring multiferroicity, half-metallic phase, and curie temperature in X = B/C/N/F-Doped KNbO3: a DFT aspect

Multiferroic materials provide an astonishing platform for next-generation spintronic devices such as magnetoresistive random access memory. Herein, ferroelectric, electronic, and magnetic properties of the pristine and X = B/C/N/F-doped KNbO3 (KNO) perovskite oxides are explored using ab initio calculations along with modified Becke-Johnson potential, where X is doped at O-site (X@O) in both KO- and NbO2-layers. Our calculations revealed that the pristine motif is a non-magnetic insulator having an energy band gap (E g ) of 2.80 eV and spontaneous polarization (P) of 41 μCcm−2, which are close to the experimentally observed values of 3.34 eV and 37 μCcm−2, respectively. The computed enthalpy of formation and elastic parameters confirm the thermodynamic and mechanical strength of the doped configurations, respectively. It is established that X-dopants significantly reduce structural distortions and have negative influence on the value of P. The most distinctive feature of the current work is that the B/N-doped KNO system for X@O in the KO-layer exhibits n-type half-metallic (HM) ferromagnetic (FM) behavior with an E g of 1.46/2.96 eV which is sufficiently large enough to prevent any magnetic transition. In contrast, C and F-doped structures are FM insulator and n-type non-magnetic metallic, respectively. Along with this, X = B/C/N-doped KNO system for X@O in the NbO2-layer displayed FM insulating nature, while the F-doped motif becomes an n-type non-magnetic metallic. The total magnetic moment for the B/N-doped structure is 1.0, which also hints the HM FM behavior. Finally, the estimated Curie temperature using the Heisenberg 2D Hamiltonian model in magnetic doped structures is found to be high enough to be used for practical purposes.

Predictive analysis of a new FeVTe alloy from first principles: An excellent choice for thermoelectric applications

To predict the thermoelectric (TE), magnetic, and electrical properties of the novel half-Heusler FeVTe as well as its dynamical, mechanical, and structural stability, this investigation makes use of the WIEN2K code and the FP-LAPW technique, which relies on density functional theory (DFT). The exchange-correlation potential in this analysis is handled using the GGA-PBE approximation. According to our predicted results, we can draw the conclusion that this compound exhibits stability in the ferromagnetic (FM) type I phase and reveals a total magnetic moment of unity. From the computed band structure, FeVTe unveils half-metallic (HM) behaviour, showing metallic features in the spin-up direction and a semiconductor character in the downspin direction with an indirect bandgap of 1.27 eV. The alloy complies with the Slater-Pauling law based on the predicted spin-polarized magnetic moments (MMs). Also, the results obtained for the elastic constants suggest that this material is ductile, anisotropic, and mechanically stable. Moreover, this compound demonstrates a remarkable figure of merit at room temperature and elevated temperatures, suggesting its potential as promising material for thermoelectric applications.

The first-principles study on the magnetic and electronic properties of Janus Cr-based MXene

Using the first-principles calculations, the geometric, magnetic and electronic properties of two-dimensional Janus MXenes Cr2CAB (A/B = F, O, OH) were investigated. The results show that Cr2COF, Cr2CO(OH) and Cr2CF(OH) all exhibit A-type antiferromagnetic. The Janus MXene Cr2CO(OH) and Cr2COF are half metals with the atomic orbital of Cr-d and O-p states contributing to the metal states at the Fermi level in spin up channel. However, Cr2CF(OH) is a semiconductor. Bader charge and geometric structure analyses show that the electron transfer number difference between the O2- and F-/OH- groups and the bond length difference between Cr-O and Cr-OH/F lead to an unequal interaction at the two ends, resulting in a transition from semiconductor properties of Cr2CT2 (T = F, OH) to half metal of Cr2CAB (A = O; B = F, OH). These findings highlight the importance of surface groups on tuning the magnetic and electronic properties of MXene, which benefits to the applications of two-dimensional Janus MXenes in spintronics.

Transition metal induced- magnetization and spin-polarisation in black arsenic phosphorous

The electronic and magnetic properties of two-dimensional black Arsenic Phosphorus (b-AsP) on adsorption of Transition Metals (TM) on its surface are investigated using density functional theory (DFT) based on first principles calculations. Spin-density of states (S-DOS) and the bandstructure of all the transition metals adsorbed structures have been plotted which reveals their change from non-magnetic to magnetic behaviour. The results suggest that pristine b-AsP which is a non-magnetic semiconductor turns into a half metal ferromagnet (HMF) on adsorption of Co, Fe and Ti, and it turns into a ferromagnet (FM) on adsorption of Cr and Zr. The total magnetic moments were also calculated to further support our results and findings. Strong magnetic moments were observed for Cr, Fe and Ti adsorbed b-AsP structures. Ag, Cu and Mo adsorption over b-AsP results into non-magnetic metallic characteristics with very weak magnetic moments. This transformation from a non-magnetic semiconductor to a magnetic HMF or FM material demonstrates the potential use of b-AsP in designing spin magnetic devices for various spin-based applications.

Density functional study of electrode material for magnetic tunnel junction designed using Co2TiZ (Z = Ge, Si) Heusler alloys

Some of the important applications in the field of spintronics are spin current driven logic devices having logic gates and in read heads in the hard disk drives, magnetic random access memory (MRAM) containing non-volatile memory units and extremely complex magnetic sensor. In spintronic applications, a magnetic tunnel junction (MTJ) is considered the back bone of all such devices. With this motivation, in present study we have predicted very low resistance area (RA) product value and high tunnel magneto resistance (TMR) of two designed MTJs by using full Heusler alloys (FHA) Co2TiZ (Z = Ge, Si) as electrode and MgO as barrier layer. These used half metallic (HM) Heusler alloys (HA), have been investigated using Wien2K code, via primary standard calculations and studied electronic and magnetic properties followed by structural and magnetic phase stability. Spin based band structure along with density of state (DOS) profiles are determined by considering both generalized gradient approximation (GGA) + modified Becke–Johnson functional (mBJ) functional and GGA potentials. For the estimation of the Curie temperature (Tc) mean field approximation (MFA) was considered. After determining physical properties of considered FHAs, spin polarised transport properties are calculated by using PWCOND code embedded in Quantum ESPRESSO (QE) for designed MTJs and obtained extremely low resistance-area product (RA) product and a high value of TMR which is found very suitable for spintronic device applications.

Origin of semiconductor and half‐metallic behaviors in the perovskite materials RbXF3 (X = Co, Mn, Fe or V): A GGA + U approach

AbstractIn this paper, we study and discuss the structural, and electronic properties of the RbXF3 (X = Co, Mn, V or Fe) Perovskite Materials using the Density Functional Theory (DFT). Also, the origin of both semi‐conductor (SM) and half‐metallic (HM) characters have been outlined. The density functional theory (DFT) has been applied to illustrate the physical properties of the RbXF3 (X = Co, Mn, Fe or V) perovskite materials. The generalized gradient approximation introduced by Perdew–Burke and Ernzerhof (GGA‐PBE) with Hubbard correction has been used for modeling the physical properties of the RbXF3 (X = Co, Mn, V or Fe) perovskite compounds. The total and partial densities of states of each solar perovskite RbVF3 (X = Co, Mn, Fe or V) material have been illustrated and discussed. In addition, the contribution of the different elements: Rb, Co, Mn, Fe, V and F, has been investigated revealing the most contributing ones in the valance and conduction bands. The magnetic behavior of the studied solar perovskites RbVF3 (X = Co, Mn, Fe or V) materials, has been outlined. It is found that the perovskites RbCoF3 and RbFeF3 are half‐metallic, while the materials RbMnF3 and RbVF3 exhibit a semi‐conductor behavior.

Thermodynamic, mechanical stability, and magneto-electronic features of Ti2-based quaternary Heusler alloys Ti2CoGa1−xCux (x=0, 0.25, 0.5, 0.75, and 1): A DFT investigation

In this work, we have used the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2k code combined with the generalized gradient approximation (GGA) of the density functional theory (DFT) to study the structural, elastic, mechanical, electronic, magnetic, and thermodynamic properties of the parent ternary inverse Heusler compounds based on Titanium and Cobalt Ti2CoGa, Ti2CoCu in the Hg2CuTi-type structure and their quaternary alloys Ti2CoGa[Formula: see text]Cux ([Formula: see text], 0.5, 0.75) for the chosen concentrations using a supercell with 16 atoms. We have calculated the structural properties, such as the lattice parameters, bulk modulus, and its first derivative, which are in good agreement with those that have been obtained based on other published theoretical methods. Also, we calculated the elastic constants of the studied Heusler alloys, and we found that these materials are elastically stable, ductile, and anisotropic. Therefore, the electronic and magnetic properties indicate that Ti2CoGa exhibits a half-metallic (HM) ferromagnetic behavior, while Ti2CoCu shows a metal and a non-magnetic (NM) character. Their quaternary alloys are found to be nearly HM ferromagnetic materials, with a magnetic moment mainly due to the atom Ti. Furthermore, the quasi-harmonic Debye model, which incorporates the lattice vibrations, was used to estimate the thermodynamic effects on some macroproperties of the Ti2CoGa[Formula: see text]Cux alloys. Successful results were achieved for the variations of the primitive cell volume, bulk modulus, heat capacities, and Debye temperature with pressure and temperature, respectively, in the ranges of 0–30[Formula: see text]GPa and 0–1400[Formula: see text]K. To our knowledge, no analogous investigations on the mechanical and thermodynamic properties of the Ti2CoGa[Formula: see text]Cux ([Formula: see text], 0.5 and 0.75) alloys have been performed to date. As a result, it is predicted that Ti2CoGa[Formula: see text]Cux Heusler alloys will be promising candidates for actual applications in spintronic devices.

Sign-flipping intrinsic anomalous Hall conductivity with Berry curvature tunability in a half-metallic ferromagnet NbSe2-VSe2 lateral heterostructure.

Single-layer half-metal magnets offer exciting scope in spin electronic quantum applications owing to improved spin transport, reduced interfacial resistance and streamlined device fabrication. Herein, we report the emergence of sign-flipping intrinsic anomalous Hall conductivity (AHC) as a result of changes in Berry curvature under an external electric field and half metallicity in a lateral heterostructure composed of centrosymmetric metallic monolayers 1T-NbSe2 and 1T-VSe2. The metallic monolayers 1T-NbSe2 and 1T-VSe2 laterally interfaced along the zigzag orientation break inversion symmetry at the interface and result in distinctive Berry curvature features. Furthermore, the half-metallic character was prominent with gapped states in the spin-up channel, while the spin-down state remained conductive; we observed the unique manifestation of sign-flipping intrinsic AHC at the Fermi level in addition to the electron- and hole-doped regions. This sign-flipping aspect of AHC at the Fermi level is of fundamental importance from the prospect of real-time device applications as it eliminates the necessity of supplementary actions, such as doping and strain engineering, which are traditionally employed to achieve AHC sign reversal. Additionally, a phase transition from half metal to metal occurs at a field of 0.5 V Å-1 and beyond. Half metallicity with sign switching AHC via external electric field makes the lateral NbSe2-VSe2 heterostructure a potential candidate for real-time energy-efficient low-power spintronic devices.

Ab initio investigations of the structure-stability, mechanical, electronic, thermodynamic and optical properties of Ti2FeAs Heusler alloy.

In this study, we employed density functional theory coupled with the full-potential linearized augmented plane-wave method (FP-LAPW) to investigate the structural, electronic, and magnetic properties of the Ti2FeAs alloy adopting the Hg2CuTi-type structure. Our findings demonstrate that all the examined structures exhibit ferromagnetic (FM) behaviour. By conducting electronic band structure calculations, we observed an energy gap of 0.739 eV for Ti2FeAs in the spin-down state and metallic intersections at the Fermi level in the spin-up state. These results suggest the half-metallic (HM) nature of Ti2FeAs, where the Ti-d and Fe-d electronic states play a significant role near the Fermi level. Additionally, the obtained total magnetic moments are consistent with the Slater-Pauling rule (Mtot = Ztot - 18), indicating 100% spin polarization for these compounds. To explore their optical properties, we employed the dielectric function to compute various optical parameters, including absorption spectra, energy-loss spectra, refractive index, reflectivity, and conductivity. Furthermore, various thermodynamic parameters were evaluated at different temperatures and pressures. The results obtained from the elastic parameters reveal the anisotropic and ductile nature of the Ti2FeAs compound. These findings suggest that Ti2FeAs has potential applications in temperature-tolerant devices and optoelectronic devices as a UV absorber.

Carrier doping modulates the magnetoelectronic and magnetic anisotropic properties of two-dimensional MSi2N4 (M = Cr, Mn, Fe, and Co) monolayers.

Through extensive density functional theory (DFT) calculations, our investigation delves into the stability, electrical characteristics, and magnetic behavior of monolayers (MLs) of MSi2N4. Computational analyses indicate intrinsic antiferromagnetic (AFM) orders within the MSi2N4 MLs, as a result of direct exchange interactions among transition metal (M) atoms. We further find that CrSi2N4 and CoSi2N4 MLs with primitive cells (pcells) exhibit half-metallic properties, with respective spin-β electron gaps of 3.661 and 2.021 eV. In contrast, MnSi2N4 and FeSi2N4 MLs with pcells act as semiconductors, having energy gaps of 0.427 and 0.282 eV, respectively. When the SOC is considered, the CrSi2N4, MnSi2N4 and FeSi2N4 MLs are metals, while the CoSi2N4 ML is a semiconductor. Our findings imply the dynamics and thermodynamic stability of MSi2N4 MLs. We have also explored the influence of carrier doping on the electromagnetic attributes of MSi2N4 MLs. Interestingly, charge doping could transform CrSi2N4, MnSi2N4, and CoSi2N4 MLs from their original AFM state into a ferromagnetic (FM) order. Moreover, carrier doping transformed CrSi2N4 and CoSi2N4 MLs from spin-polarized metals to half-metals (HMs). It is of particular note that doping of CrSi2N4 MLs with +0.9 e per pcell or more holes caused a switch in the easy axis (EA) to the [001] axis. The demonstrated intrinsic AFM order, excellent thermodynamic and kinetic stability, adjustable magnetism, and half-metallicity of the MSi2N4 family suggest its promising potential for applications in the realm of spintronics.

DFT insights on the Be1-xCrxS alloys for optoelectronic and magnetic devices

In this work, the electro-optical and magnetic characteristics of Be1-xCrxS (x= 6.25%, 12.5% and 25%) are brought into investigation by employing full potential linearized augmented plane wave (FP-LAPW) scheme designed within density functional theory (DFT). The stability of the Be1-xCrxS alloy is justified by the negative values of formation energy. The band structures and density of states are examined by using GGA functional. Be1-xCrxS compound demonstrates the half-metallic (HM) ferromagnetic behavior for all doping concentrations; spin-up channel reveals the metallic character and other spin version displays the semiconductor (SC) behavior. The values of total magnetic moment (µB) are recorded as 4.0 8.0 and 16.0 µB for corresponding 6.25%, 12.5% and 25%, which mainly arises owing to Cr-3d state. Moreover, optical features including dielectric function ε(ꞷ), reflectivity, refraction, and absorption are explored within range of 0-10 eV. The maximum absorption of incident photons was found in ultraviolet (UV) span which implies their importance for optoelectronic applications. Results reveal that the studied alloy has potential applications in magnetic and optoelectronic gadgets.

Investigation of half metallic properties of Tl2Mo(Cl/Br)6 double perovskites for spintronic devices.

The manipulation of electronic device characteristics through electron spin represents a burgeoning frontier in technological advancement. Investigation of magnetic and transport attributes of the Tl2Mo(Cl/Br)6 double perovskite was performed using Wien2k and BoltzTraP code. When the energy states between ferromagnetic and antiferromagnetic conditions are compared, it is evident that the ferromagnetic state exhibits lower energy levels. Overcoming stability challenges within the ferromagnetic state is achieved through the manipulation of negative ΔHf within the cubic state. The analysis of the half metallicity character involves an analysis of band structure (BS) and DOS, elucidating its mechanism through PDOS using double exchange model p-d hybridization. The verification of 100% spin polarization is confirmed through factors such as spin polarization and the integer value of the total magnetic moment. Furthermore, the thermoelectric response, as indicated by the ratios of thermal-electrical conductivity and ZT, underscores the promising applications of these compounds in thermoelectric device applications.

Emergence of exotic electronic and magnetic phases upon electron filling in Na2BO3 (B = Ta, Ir, Pt, and Tl): a first-principles study.

Competition between spin-orbit interaction and electron correlations can stabilize a variety of non-trivial electronic and magnetic ground states. Using density functional theory calculations, here we show that different exotic electronic and magnetic ground states can be obtained by electron filling of the B-site cation in the Na2BO3 family of compounds (B = Ta, Ir, Pt and Tl). Electron filling leads to a Peierls insulator state with a direct band gap to j = 1/2 spin-orbit assisted Mott-insulator to band insulator and then to negative charge-transfer half-metal transition. The magnetic ground state also undergoes a transition from a non-magnetic state to a zigzag antiferromagnetic state, a re-entrant non-magnetic state and finally to a ferromagnetic state. The electron localization function shows a ladder type dimerization or Peierls instability in Na2TaO3. Maximally localized Wannier function calculations reveal delocalization of electrons through the eg orbitals, which form a π bond, and localization of electrons through the t2g orbitals, which form a σ bond, between the neighbouring tantalum ions. Na2TlO3 shows Stoner or band ferromagnetism due to the localized moments with up-spin on oxygen ligands created by the negative charge-transfer character, interacting via the down-spin itinerant electrons of the Tl 5d-O 2p hybridized band. These findings are significant for practical applications; for instance the direct band gap insulator Na2TaO3 shows potential for utilisation in solar cells, while Na2TlO3, which exhibits ferromagnetic half metallicity, holds promise for spintronic device applications.

Constructing Efficient and Thermostable Red‐NIR Emitter via Cross Relaxation and Crystal‐Field Engineering of Holmium‐Based Perovskite‐Type Half Metal

AbstractLanthanide ions, as dopants, have evoked widespread research interest owing to the rich optical, magnetic, and electrical properties, but their luminescent intensity is always limited by typical concentration quenching. Herein, a holmium‐based double perovskite of Cs2NaHoCl6 is reported, which surprisingly breaks through this barrier and achieves efficient red‐NIR emission by virtue of the large unit cell, low phonon energy, high content of activators, and cross relaxation phenomenon between Ho3+. The heavy Ho3+ also endows the intriguing half‐metallic nature with a down‐spin conducting band and an up‐spin insulating band. After performing ion doping on crystallographic sites of Na+ and Ho3+, the photoluminescence quantum yield of such red‐NIR emitter under 450 nm excitation is dramatically promoted to 82.3%, benefiting from the improved crystal field environment that alleviates the parity forbidden rule and suppresses non‐radiative recombination loss. Furthermore, the heat‐favorable phonon‐assisted population processes enable the robust photostability against thermal quenching. By combining a 450 nm chip, the red‐NIR light‐emitting diodes are fabricated, in which the wide‐coverage NIR emissions are ideally suited for medical light source, night vision, nondestructive examination, and transmission imaging. It is believed that this work will open an avenue for enhancing the fluorescence of lanthanide ions and developing advanced spintronic materials.

A Device Model for Achieving Sizable and Tunable Tunneling Magnetoresistance Using Two‐Dimensional Materials InX (X = O, Se) without Hetero‐Interface

AbstractThe two‐dimensional (2D) materials InX (X = O, Se), experimentally available thus far, can become a ferromagnetic half metal under hole doping, though the charge neutral states of them are nonmagnetic semiconductors. Based on such an electronic characteristic, a theoretical model of magnetic tunnel junction (MTJ) is proposed composed only of one of the 2D InX. In doing so, the two semi‐infinite pieces of 2D InX in the half‐metallic state is assumed as the opposite electrodes which are separated by a strip of the same material but in its nonmagnetic state. Owing to the 2D nature of InX, the half metal electrodes of the InX device induced by hole doping can be achieved by using split gating technique. The numerical simulations identify a proper hole doping concentration, at which 100% tunneling magnetoresistance (TMR) ratios can be realized, accompanying an appreciable conductance of majority spin electron under parallel magnetization configuration. Under a finite bias voltage, the TMR ratio remains high. Therefore, the proposed device model is an ideal candidate for future spintronics applications. It enables electrical control of TMR and circumvents the detriment of hetero‐interface disorder inevitable in conventional MTJs.

Emerging half metal electrides in manganese oxyarsenide hydrides LaMnAsOH x

In the paper, we report that the hydrides LaMnAsOH x can serve as a switchable half-metal electride which combines the dual properties of half metals and electrides. Using density functional theory calculations, it is found that this hydride compounds exhibit a novel magnetic structure in which magnetic electrides arising from the excess electrons induced by the H dopants coexist with local-moment antiferromagnetism of the Mn spin lattice. While the reported sizable negative magnetoresistance and ferromagnetism are merely contributed by the spin polarization of excess electrons, this material mimics the behavior of a switchable half-metal electride because the completely spin polarization of excess electrons is easily achieved by controlling the concentration of conductive electrons or H dopants. These effects look very promising for continuing the rapid pace of spintronics application.

Computations on platinum based ternary ferromagnetic half metals for spin valve diodes and green energy technology based thermoelectric

The ab initio method commonly known as wavefunction method is used to calculate the structural, mechanical, electronic, magnetic, lattice dynamical and thermoelectric properties of the half metallic half-Heusler alloys VPtZ (Z = Si, Ge, Sn). The equilibrium lattice constants and corresponding ground state energies of the studied alloys are computed in stable ferromagnetic γ-phase with a cubic structure. The electronic properties suggest that the compounds are half metals with indirect band gap having the band energies of 1.02 eV, 1.04 eV and 0.9 eV for VPtSi, VPtGe and VPtSn, respectively, in the spin down channel. The materials have spin magnetic moment of 1 μB, suggest that the materials are suitable for making spintronic devices such as spin valve diodes. Temperature dependent heat transport properties were studied by using classical Boltzmann theory. The materials have high power factor at high temperatures. Thermoelectric performance of the materials is calculated between the temperature range 100–1200 K respectively. The obtained thermoelectric figure of merit for p-type VPtSi, VPtGe and VPtSn are 0.4, 0.7 and 0.3, respectively, at 1200 K. Similarly, the figure of merit obtained for n-type VPtSi, VPtGe and VPtSn are 0.41, 0.75 and 0.3, respectively, at the same temperature. The favourable energy and spin transport properties of these alloys show that they are the potential candidates as thermoelectric for heat energy harvesting and spintronic for magneto electronics applications.