Half-metallic Gap Research Articles

Computational characterization of structural, electronic, elastic and magnetic properties of double half-Heusler alloy Fe2MnCoGe2

Using the augmented plane wave method based on density functional theory and implemented in the WIEN2k code, we study the structural, elastic, electronic, and magnetic properties of FeCoGe, FeMnGe, and the parent half-Heusler (HH) alloys, as well as their derivative Fe2CoMnGe2 double half-Heusler (DHH) compounds. By analysing the stability of the HH structure in both the ferromagnetic and non-magnetic phases of FeCoGe and FeMnGe alloys, we determine that the latter phase of type II and type III FeCoGe and FeMnGe arrangements is the most stable. The Fe2CoMnGe2 DHH alloy, which is derived from the magnetic and structural ground states of FeCoGe and FeMnGe HH alloys, is found to be most stable in the type II arrangement. Among these materials, the FeMnGe HH alloy demonstrates greater resistance to reversible deformation by shear strain, indicated by its higher Young's modulus, while FeCoGe shows the best overall resistance to deformation. The electronic structures of FeCoGe, FeMnGe, and Fe2CoMnGe2 compounds reveal metallic behavior in the spin-up channel and semiconducting behavior in the spin-down channel. Their half-metallic gaps are 0.437 (0.181) eV, 0.543 (0.224) eV, and 0.353 (0.035) eV, respectively, with Fe2CoMnGe2 DHH retaining half-metallicity despite a lower band gap. The total magnetic moments for FeCoGe, FeMnGe, and Fe2CoMnGe2 are found to be 3, 1, and 4 μB, respectively. Given their half-metallic properties, these alloys show potential as candidates for spintronic applications.

High Curie temperature in Zn(Co,Ni)Se: DFT study

In this work, we aimed to examine the first-principles study of correlation between chemical environment and ferromagnetism, and Curie temperature of CoxZn1-xSe and NixZn1-xSe diluted magnetic semiconductors for different concentrations of impurity atoms. The calculations are implemented by the norm-concerving FHI pseudopotential method within the local spin density approximation (LSDA) and Hubbard U method. The analysis of the total density of states curves shows the half-metallic ferromagnetic character with half-metallic band gap. The first-principles calculated total magnetic moments of CoxZn1-xSe and NixZn1-xSe systems are found to be equal to 3 and 4 µB, respectively.

A DFT theoretical prediction of new half-metallic ferromagnetism, mechanical stability, optoelectronic and thermoelectric properties of ZnCrO3 perovskites for spintronic applications

ZnCrO3 perovskites structural stability, optoelectronic, mechanical, along with thermoelectric properties, have all been to be described by calculations based on density functional theory (DFT). To determine the exchange correlation potential, the well-known generalized gradient approximation (GGA) and integration of the mBJ potential were used. The perovskite shows that this is in a cubic structure with Fm3m symmetry. Additionally, to check the stability, cohesive energy, structural optimization, and mechanical stability were requirements. This perovskite was found to be brittle, and their mechanical stability enhanced by the elastic constants. The perovskite has a half-metallic character, as evidenced by the spin-polarized electronic band profile, the behavior of the dielectric constant, and absorption coefficient in the spin-up and down channels. In this article, we also looked at magnetism and the origin of the half-metallic gap. The unpaired electrons in the split d-orbitals of the M-sited elements in the crystal field are responsible for the half-metallic as well as magnetic characteristics. Excellent spin polarization at the Fermi level encourages perovskite's possible use in spintronic technologies. Lastly, we computed the thermoelectric parameters within a chemical potential at various temperatures (300 K, 600, 900 K) to explore the potential application in spin electronic devices. Our finding shows that the ZnCrO3 alloy is exceptionally promising for the next generation of spintronics and thermoelectric devices at room and high temperatures.

Deciphering the evolution of electronic and magnetic properties in alkali doped nickel oxide: An In-silico approach

In this study, we employed the DFT+U method to systematically explore the electronic, and magnetic properties of nickel oxide doped with alkali metal atoms (Li, Na, K). The Hubbard potential-U was judiciously applied to all doped compound resulting from alkali doping, and were found to exhibited half-metallic properties. A noteworthy observation was the half-metallic band gap in the spin-down channel, which exhibited a linear variation with the increasing value of the Hubbard potential. Furthermore, the total magnetic moment was discernible in the supercells, with all supercells demonstrating 100% spin polarization at the Fermi level. Consequently, the findings from this study hold significant potential for applications in spintronics, thereby paving the way for future research in this domain.

Structural stability, induced magnetism and half-metallic band gaps in Cr-substituted GaSb: novel prediction via semi-local potential

Structural stability, induced magnetism and half-metallic band gaps in Cr-substituted GaSb: novel prediction via semi-local potential

Investigation of thermodynamical stability and generation of large half-metallic gap along with optical properties in N-doped YHfO3 (YHO) (Y = Ca, Sr, and Ba) perovskite materials by first principle calculations

Considerable energy gap (Eg) in insulating channel, high spin-filtering, significant mean free path, and high magnetic transition temperature (TC) escalate half-metallic (HM) ferromagnetic (FM) materials very enticing for spintronic applications. Herein, ab-initio calculations have been executed comprehensively to inquest the structural, thermodynamical, electronic, magnetic, and optical properties of pure as well as nitrogen (N)-doped YHfO3 (YHO) (Y = Ca/Sr/Ba) materials with one N atom added at one of the oxygen (O) site. First, the thermodynamical stability of both bulk and doped YHO systems has been examined by estimating the formation enthalpies (ΔHf) by Convex Hull analysis, which confirms the practical realization of these materials on experimental grounds. Moreover, mechanical stability of these systems is affirmed by estimating the necessary elastic constants and respective parameters. Strikingly, all doped systems possess complete (100%) splitting in spin↑ and spin↓ channels at Fermi level and depict HM FM character with significant Eg of 3.31, 3.49, and 3.24 eV in spin↓ channels for CaHO (CHO), SrHO (SHO), and BaHO (BHO) systems, respectively. It is also found that N 2p orbitals are totally responsible for the emergence of metatallicity and magnetic character in all these doped structures. Moreover, the ground state long range FM stability between two added N atoms in doped systems is affirmed by computing the difference of total energies of FM and anti-ferromagnetic (AFM) spin ordering (ΔE) along with estimated TC at different distances. Lastly, it is found that N-doped systems have a lower optical energy loss than pristine YHO systems in the incident photon energy range of 0-50 eV. Hence, the present study proposes that an unconventional doping approach with intrinsically non-magnetic element in a variety of YHO perovskite systems could be a useful method to alter their various physical properties and forecast their potential applications in the development of novel spintronic and optoelectronic devices.

The intrinsic ferromagnetic half-metals with high Curie temperature of tetragonal XCrS4 (X=Ti, Zr) monolayer

Two-dimensional intrinsic magnetic materials with a high Curie temperature (TC) and 100% spin-polarization are highly desirable for creating spintronic devices. In this work, the electronic structure and intrinsic magnetism of XCrS4 (X = Ti, Zr) monolayers are predicted by using first-principles calculations. XCrS4 (X = Ti, Zr) monolayer materials exhibit excellent dynamical, thermal, and dynamically stable stability and small binding energy. The band structures show that XCrS4 (X = Ti, Zr) monolayers are intrinsic ferromagnetic (FM) half-metals with wide half-metallic gaps. Monte Carlo simulations based on the Heisenberg model are used to estimate the Curie temperature (TC) of the TiCrS4 (73 K) and ZrCrS4 (216 K) monolayers. The magnetic performances can be significantly modulated by strain; the TiCrS4 monolayer can undergo FM to antiferromagnetic phase transition under certain uniaxial and biaxial strains. The results indicate that the intrinsic half-metals with higher TC and controllable magnetic properties make XCrS4 (X = Ti, Zr) monolayers enrich the application of nanoscale spintronic devices.

Investigating the multifaceted characteristics of Ba2FeWO6 double perovskite: Insights from density functional theory

This study undertook a comprehensive examination of the double perovskite complex Ba2FeWO6, investigating its structural, electrical, magnetic, thermal and elastic characteristics. The study used density functional theory (DFT), specifically the full potential linearized augmented plane wave (FP-LAPW) method. It also used different approximations, including the generalized gradient approximation (GGA) and the modified Trans-Blaha (TB-mBJ) approach, to improve the accuracy of the band gap estimation more accurate. Additionlly, the GGA + U approach, incorporating the Hubbard correction term (U), was utilized. Our findings indicate that Ba2FeWO6 exhibits indirect half-metallic band gaps in the (L-X) direction, with value of 0.91 eV and a net magnetic moment of 4 μB, predominatly influenced by the iron atom. The compound demonstrated exceptional characteristics suitable for thermoelectric applications, particularly at lower temperatures. Furthermore, the elasticity analysis revealed low brittleness, facilitates its manipulation in manufacturing procedures.

First-principles study of the structure, magnetism, and electronic properties of the all-Heusler alloy Co2MnGe/CoTiMnGe(100) heterojunction.

Based on first-principles calculations in the density functional theory, we systematically investigated the possible interface structure, magnetism, and electronic properties of the all-Heusler alloy Co2MnGe/CoTiMnGe(100) heterojunction. The calculation indicated that the Co2MnGe Heusler alloy is a half-metal with a magnetic moment of 4.97μB. CoTiMnGe is a narrow-band gap semiconductor and may act as an ultra-sensitive photocatalyst. We cannot find an "ideal" spin-polarization of 100% in CoCo termination and MnGe termination. Due to the interface interaction, the direct magnetic hybridization or indirect RKKY exchange will be weakened, leading to an increase in the atomic magnetic moment of the interfacial layer. For eight possible heterojunction structures, the half-metallic gaps in the Co2MnGe bulk have been destroyed by the inevitable interface states. The spin-polarization value of 94.31% in the CoCo-TiGe-B heterojunction revealed that it is the most stable structure. It is feasible to search for high-performance magnetic tunnel junction by artificially constructing suitable all-Heusler alloy heterojunctions.

Determination of half metallicity behavior of quaternary heusler alloy crcoscga

In this work, the theoretical study through the calculations of the structural, electronic and magnetic properties of quaternary heusler compound CrCoScGa, using wien2k code, is reported. We adopted the generalized gradient approximation (GGA) to estimate the exchange correlation potential. The negative value of the formation energy shows that CrCoScGa compound have a high structural stability in the type III structure feromagnetic phase, so it can be experimentaly synthetised. According to our electronic calculations, CrCoScGa is a half-metallic ferromagnet (HMF) with a half-metallic gap of 0.22 eV. The total magnetic moment of 3µB, mainly originated from Cr and Co atoms, makes this alloy as a spintronic material.

First-principles calculations on the mechanical, electronic, magnetic and optical properties of two-dimensional Janus Cr2TeX (X= P, As, Sb) monolayers

Janus materials possess extraordinary physical, chemical, and mechanical properties caused by symmetry breaking. Here, the mechanic properties, electronic structure, magnetic properties, and optical properties of Janus Cr2TeX (X= P, As, Sb) monolayers are systematically investigated by the density functional theory. Janus Cr2TeP, Cr2TeAs, and Cr2TeSb are intrinsic ferromagnetic (FM) half-metals with wide band gaps between spin-down channel and half-metallic gaps. The Curie temperature (Tc) of these monolayers are about 583, 608, and 597 K, respectively by Monte Carlo simulations based on the Heisenberg model. Additionally, it has been found that Cr2TeX (X= P, As, Sb) monolayers still exhibit FM half-metallic properties under biaxial strain ranging from −6% to 6%. At last, the Cr2TeP monolayer has a higher absorption coefficient than the Cr2TeAs and Cr2TeSb monolayers in the visible region. The results predict that Janus Cr2TeX (X= P, As, Sb) monolayers with novel properties have good potential for applications in future nanodevices.

First-principles studies of the stability, structural, electronic, magnetic and optical properties of halogen atom doped marcasite FeS2

The effects of halogen atom (F, Cl, Br or I) doping on the stability, structural, electronic, magnetic and optical properties of marcasite FeS2 (m-FeS2) are investigated through the first-principles calculations. The formation energies are relatively small under Fe-rich condition, indicating that it is feasible to implant halogen atom into m-FeS2. The ground state of halogen atom doped m-FeS2 systems is magnetic due to the positive energy differences between non-spin-polarized and spin-polarized states. Phonon dispersion curves show that all doping systems are dynamically stable. The total magnetic moment of all doping systems is nearly 1μB, since replacing the S atom with a halogen atom introduces a non-bonding electron. Most of them come from Fe and S atoms, and only a small fraction come from the dopant. The simulation results show that F- and Br-doped m-FeS2 systems are still semiconductors although the band gaps are reduced considerably, Cl-doped m-FeS2 changes to a half-metal with half metallic band gap of 0.25 eV, while I-doped m-FeS2 becomes a metal, making them potentially useful in spintronics. In addition, the halogen atom doped m-FeS2 systems possess enhanced absorption coefficient and red-shifted absorption edge. So they are promising in optoelectronic device and solar energy harvesting.

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.

The structure, magnetism and mechanical properties of L21-type full-Heusler alloy Cr2ZrSi: A first-principles study

Heusler alloy is a widely studied spintronic material in recent years, which has played a huge role in the field of spintronic devices due to its high spin polarization and high Curie temperature. Using first-principles calculation to predict the basic properties of Heusler alloy can not only save experimental costs and time but also provide a reliable theoretical basis for experimental research. This study used a first-principles calculation to study the magnetic and mechanical properties of full-Heusler alloy Cr2ZrSi with an L21-type structure. The research results indicate that the alloy is a half-metallic ferromagnetic material with a theoretical value of 100% spin polarization. The magnetism mainly comes from the asymmetric spin contribution of d-orbital electrons of transition metal atoms and their hybridization. At the same time, this complex hybridization coupling process is also a possible reason for the half-metallic band gaps. In terms of mechanical properties, the Cr2ZrSi alloy exhibits good ductility and anisotropy, with a Debye temperature of 303.848K. Our theoretical research results provide more choices and theoretical basis for subsequent experimental research.

Novel Prediction Using TB-mBJ of Electronic Properties, Magnetic Exchange Couplings, and Half-Metallicity in CrCaSe Materials

In this study, we have performed investigations on the structural stability, elec-tronic band structures, magnetic exchange couplings, and half-metallic performance of CrxCa1-xSe materials using computational methods of density functional theory via GGA-WC, GGA-PBE and, TB-mBJ exchange-correlation potentials. The CrxCa1–xSe compounds are thermodynamically stable and synthesizable owing to their negative formation energies. The structural parameters of CrxCa1–xSe with GGA-WC and GGA-PBE approximations appear to be in excellent concordance compared to the experi-mental data and recent theoretical calculations. According to GGA-PBE and TB-mBJ calculations, the CrxCa1–xSe compounds revealed integral magnetic moments and a half-metallic behavior with better half-metallic gaps, and spin-polarization of 100%. The CrxCa1–xSe alloys appear to be better materials for use in spintronic devices.

Investigation of structural, magnetic, mechanical, electronic and thermal properties of new quaternary Heusler: KMgNZ (Z=O or S)

The structural stability as well as the mechanical, magnetoelectronic and thermal properties of the quaternary Heusler KMgNZ (Z = O or S) were studied using first principles approach based on the DFT implemented in Wien2k code. The exchange-correlation potential is treated by PBE-GGA. The calculated negative formation energies for both materials corroborate their thermodynamic stability. Moreover, the derived elastic constants support the mechanical stabilities of the latter compounds. On the other hand, the density of states of the studied materials shows that both compounds are half-metallic ferromagnets. The total magnetic moments for both compounds are mainly originated from N atom, and its integer value followed the Slater-Pauling rule. The calculated half-metallic gaps are found for two systems. The three-dimensional plots of different mechanical moduli exhibit that the bulk modulus is isotropic, whereas Young's modulus, Poisson's ratio and shear modulus of both compounds are highly anisotropic. The effects of temperature and pressure on the heat capacity, thermal expansion coefficient and Debye temperature are also studied.

DFT+U, TB-mBJ, and hybrid approaches: investigating electronic topology and magnetic properties in Sn-doped Co2TiGa

Cobalt-based Heusler compounds represent a new class of Heusler alloys which absorbed a lot of attention due to their performance in spintronics and magnetic devices. in this paper we have studied and analyzed the electronic structure and half-metallic ferromagnetic properties of Co2TiGa and Sn substituted at Ga site via the density functional theory (DFT) based first principle calculations with GGA-PBE, PBE+U, TB-MBJ exchange correlation potential and HSE06 approach. The band structure topology indicates that the parent ternary Heusler compound is ferromagnetic half-metallic with a half-metallic gap (band gap in the minority channel). The gap is increased according to the correction made on the exchange correlation potential. The half-metallic ferromagnetic behavior is confirmed by the total magnetizations which are very close to integrals Bohr magneton (1 μ B and 3μ B for Co2TiGa and Mn2TiGa0.5Sn0.5, respectively). The origin of half-metallic ferromagnetic is the p − d exchange and double-exchange interaction between the Co d-t2g states and neighboring Ti atom. The substitution effect on half-metallicity for Co2TiGa0.5 Sn0.5 was investigated in the tetragonal structure. The spontaneous magnetization obeyed the Slater-Pauling rule, indicating the Co2TiGa0.5 Sn0.5 is half-metal with 100% spin polarization.

Thermoelectric, mechanical, and pressure sustained half-metallic properties of BaInO3 perovskite for spintronics applications: DFT computation

Oxide perovskites continue to promote research interest because of their concurrent use in spintronic and thermoelectric applications. The electronic, magnetic, and thermoelectric properties of new half-metallic BaInO3 perovskite are investigated using the density functional theory. The structural and thermodynamic stability of the proposed perovskite is provided by the tolerance factor, octahedral factor, formation energy, and phonon dispersion curves. The structural relaxation curves reveal that the ground state is ferromagnetic. The generalized gradient approximation and mBJ band structure plots show that the half-metallicity exclusively results from the strong exchange splitting of 2p-bands at the Fermi level. Compared with PBE, mBJ depicts highly localized magnetic moments around oxygen along with enhanced half-metallic gaps and band gaps in the spin-up channel. Under a compressive strain, the system undergoes a magnetic phase transition from half-metallic ferromagnet to non-magnetic metal at 30 GPa. The elastic stability at the studied pressure range has been verified from Blackman’s and Every’s diagrams. The material remains ductile and exhibits moderate elastic anisotropy in the studied pressure range. The quasi-harmonic Debye model is employed to study the temperature and pressure effects of thermodynamic parameters. The computed transport properties including the Seebeck coefficient and spin-Seebeck coefficient predict reasonable thermoelectric performance in generating thermally induced spin-polarized current and spin current, respectively. Such a detailed study of this material could open prospects in spintronic as well as waste energy recovery devices.

Investigations on stability, Gilbert damping, electronic and magnetic properties along with Curie temperature for quaternary Heusler alloys CrTiCo[formula omitted

In the current manuscript, we systematically investigated the stability, Gilbert damping parameters, electronic and magnetic properties, exchange interactions and Curie temperatures of quaternary Heusler alloys CrTiCoZ (Z=Al, Ga, In). Stability calculations show that the CrTiCoZ alloys meet mechanical, thermodynamic and dynamic stabilities. Gilbert damping parameters of CrTiCoZ alloys calculated via linear response theory are localized in 0.006∼0.054 at 300 K, indicating they have lower energy loss and higher response speed as microwave and spintronic materials. Electronic calculations indicate that the CrTiCoIn is half-metallic ferrimagnet, and its integer total magnetic moment obeys the Slater–Pauling rule: Mt=Zt-18, while the CrTiCoAl and CrTiCoGa are nearly half-metals. After applying the GGA+U and HSE06 methods, it was found that the CrTiCoAl and CrTiCoGa alloys exhibit half-metallic properties. However, the CrTiCoIn alloy loses its half-metallicity. Origin of half-metallic gap is discussed by hybridization, occupation and distribution of electronic states. According to the Heisenberg model, we calculated the exchange coupling parameters of CrTiCoZ alloys, and found that the competition and cooperation between d-d exchange and RKKY exchange lead to the emergence of ferrimagnetic phase. Finally, we estimated the Curie temperatures of CrTiCoZ alloys by using mean-field approximation and Monte Carlo simulation, the calculated Curie temperatures are noticeably higher than room temperature. High spin polarization and Curie temperature as well as lower Gilbert damping parameters make the CrTiCoZ alloys as a promising material for microwave or spintronics applications.

First principle studies on half-metallicity and pressure-induced half-metallic band gap in 3-d transition metal-based quaternary Heusler ScVCoZ (Z = Si, Ge, Sn, P, As, and Sb) alloys

In the present work, we predict a series of 3-d transition metals-based quaternary Heusler alloys (QHA) ScVCoZ (Z = Si, Ge, Sn, P, As, and Sb) (SVCZ), by employing density functional theory (DFT) calculations. We carried out extensive band structure (BS) and density of states (DOS) analysis to explain the half-metallic and magnetic behavior of the alloys. We found that SVCZ alloys stabilize in the F 4̅ 3m space group and exhibit a ferromagnetic (FM) ground state (GS). Among the QHAs, SVCZ (Z = Si, Ge, and Sb) exhibit intriguing half-metallic properties featuring 100% spin polarization at the Fermi level (EF). Additionally, the effect of pressure indicates a band gap opening in one of the spin channels for SCVZ (Z = P, and As), and the half-metallic characteristics are retained up to a compressive pressure, respectively of 65, and 79 GPa for SCVP and SCVAs. Elastic properties calculations suggest SVCZ alloys satisfy Born stability criteria and are mechanically stable. Among the predicted QHAs, SVCZ (Z = Si, Ge, and Sn) shows brittle nature, whereas SVCZ (Z = P, As, and Sb) are ductile.