Integer Magnetic Moment Research Articles

First-principle study origin of ferromagnetism in non-magnetic perovskite BaSnO3 doped with 2p-X (X=C, N)

In this study, our goal is to analyze the origin of magnetization in non magnetic cubic structure perovskite BaSnO3 doped with 2p-X (X=C, N) using the full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). For the exchange and correlation potential we have applied the generalized gradient approximation (GGA) and the GGA plus-modified Becke-Johnson potential (mBJ-GGA). The results show that BaSnO3 doped with C then with N and finally with C and N exhibit half-metallic ferromagnetism behavior with the integer magnetic moment of 1, 2 and 3 μB per cell respectively. The origin of the ferromagnetism that occurs within these compounds is mainly caused by the p-p hybridization between 2p-impurities and its neighboring oxygen atoms. These results allowed to conclude that doped perovskite could provide a new type of materials, called half-metallic for future spintronic devices.

Unveiling half-metallic, thermoelectric and optoelectronic behavior of the new Heusler alloy RbCrZ (Z = Si, Ge): a DFT perspective

Abstract Utilizing the density functional theory (DFT) method, this study aims to predict with precision the structural, elastic, electronic, magnetic, thermoelectric, thermal, and optical properties of two recently discovered half-Heusler alloys, namely RbCrSi and RbCrGe. The exchange and correlation potential are accounted for using the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE) and the Tran–Blaha-modified Becke–Johnson exchange potential (TB-mBJ). Through structural analysis, it is observed that both RbCrSi and RbCrGe alloys exhibit energetic stability in a type-3 structure with a ferromagnetic (FM) state. Both alloys exhibit half-metallic properties and integer magnetic moments of 3 μB, following the Slater-Pauli rule. Additionally, elastic calculations confirm their mechanical stability and anisotropic ductile behavior. The quasi-harmonic Debye model (QHDM) is employed for calculating thermodynamic properties, while the BoltzTraP code, based on semi-classical Boltzmann theory (SCBT), is utilized for evaluating thermoelectric properties. Findings reveal that RbCrZ alloys (with Z = Si, Ge) exhibit high figure of merit (ZT) values nearing unity at highest temperature. Consequently, the newfound half-Heusler alloys RbCrSi and RbCrGe hold significant promise for applications in thermoelectricity and spintronic devices. This comprehensive analysis underscores the potential of these alloys in the realm of renewable energy applications.

Adsorption of Ag, Au, Cu, and Ni on MoS2: theory and experiment

Here, we present results of a computational and experimental study of adsorption of various metals on MoS2. In particular, we analyzed the binding mechanism of four metallic elements (Ag, Au, Cu, Ni) on MoS2. Among these elements, Ni exhibits the strongest binding and lowest mobility on the surface of MoS2. On the other hand, Au and Ag bond very weakly to the surface and have very high mobilities. Our calculations for Cu show that its bonding and surface mobility are between these two groups. Experimentally, Ni films exhibit a composition characterized by randomly oriented nanoscale clusters. This is consistent with the larger cohesive energy of Ni atoms as compared with their binding energy with MoS2, which is expected to result in 3D clusters. In contrast, Au and Ag tend to form atomically flat plateaued structures on MoS2, which is contrary to their larger cohesive energy as compared to their weak binding with MoS2. Cu displays a surface morphology somewhat similar to Ni, featuring larger nanoscale clusters. However, unlike Ni, in many cases Cu exhibits small plateaued surfaces on these clusters. This suggests that Cu likely has two competing mechanisms that cause it to span the behaviors seen in the Ni and Au/Ag film morphologies. These results indicate that calculations of the initial binding conditions could be useful for predicting film morphologies. In addition, out calculations show that the adsorption of adatoms with odd electron number like Ag, Au, and Cu results in 100% spin-polarization and integer magnetic moment of the system. Adsorption of Ni adatoms, with even electron number, does not induce a magnetic transition.

Ferrimagnetic half metals TaMnZ (Z = As, Sb, Bi) for thermoelectric and spintronic applications – Material computations

Half metals possess coupling behavior of metals and semiconductors with wide heat transport and spin transport properties. This research article covers the structural, mechanical, electronic, magnetic and thermoelectric properties of the half Heusler alloys TaMnZ (Z = As, Sb, Bi). The equilibrium lattice constants and corresponding ground state energies show that the studied alloys are stable in the ferrimagnetic cubic phase. The band dispersion plots suggest that the compounds TaMnAs, TaMnSb and TaMnBi are half metals with indirect band gap having the band gap energies of 1.13 eV, 1.24 eV and 1.12 eV respectively in the spin down channel. As the materials have 100 % spin polarization with an integer magnetic moment of −1 μB, they are suitable for making spintronic devices such as spin transistors and spin-flip flops. The temperature-dependent thermoelectric properties of the alloys have been studied by classical Boltzmann theory. The materials have low lattice thermal conductivity which was confirmed by Slack’s equation. The obtained thermoelectric figure of merit for p-type TaMnAs, TaMnSb and TaMnBi is 0.7, 0.6 and 0.8 respectively at 1200 K. Similarly, the figure of merit obtained for n-type TaMnAs, TaMnSb and TaMnBi is 0.6, 0.64 and 0.8 respectively at the same temperature. The favourable heat and spin transport properties of these alloys show that they are the potential characters to figure out better thermoelectric and spintronic performance.

Computational survey of optoelectronic properties and half-metallicity in ZnFeMnS: insight from first principles calculations

The electronic structure, optic and magnetic properties of the ZnFeMnS quaternary compound are studied on the basis of band-structure calculations, using full-potential linearized augmented plane wave (FPLAPW) method. The calculations are performed within the generalized gradient approximation (GGA). The calculated results indicate that ternary ZnMnS has an insulating character for the two directions of spin so, in its current form, it is inappropriate for spintronics devices. In contrary, Fe/Mn codoped ZnS is a half-metallic (HM) ferromagnet with a magnetic moment of 9 μB per formula unit. The integer magnetic moment of this compound indicates the stability of its half-metallic behavior. Consequently ZnFeMnS could be a promising dilute magnetic semiconductor for application in spintronic devices. Moreover, we have computed optical properties (absorption coefficient and reflectivity) of the two compounds, and have found a pronounced peak occurring at low energies for ZnFeMnS in all the optical curves due to transition metal (TM) impurity. The improvement of optical properties allows this compound to be used in manufacturing photovoltaic static converter or in display devices.

First-principles calculations of structural, magneto-electronic, mechanical, optical and thermoelectric properties of novel quaternary Heusler alloys type ZrCoYAs (Y= Fe and Mn)

To determine the structural, mechanical, electronic, magnetic, optical, and thermoelectric properties of novel quaternary Heusler alloys type ZrCoYAs (Y= Fe and Mn), we used DFT with WIEN2k. Our results showed that the ferromagnetic Y-type-III phase is more stable due to the higher negative values of their formation energy. We calculated and discussed the elastic constants Cij, which are used to calculate the mechanical properties. The Spin-polarized band structure and DOS calculations using the GGA-PBE and GGA + U approach display a metallic character. However, using the mBJ-GGA-PBE and mBJ-GGA + U approach show a half-metallic character, a semiconductor for the spin-down channel with a direct band gap of 0.61 eV with mBJ-GGA-PBE and 0.74 eV with mBJ-GGA + U for ZrCoMnAs and a direct band gap of 0.43 eV with mBJ-GGA-PBE and indirect band gap with 0.39 eV with mBJ-GGA + U for ZrCoFeAs, in contrast, the spin-up channel is metallic, with 100 % spin polarization and an integer magnetic moment of 1.00 μB for ZrCoMnAs and 2.00 μB for ZrCoFeAs, obeying the Slater-Pauling rule. The estimated Curie temperatures of ZrCoMnAs and ZrCoFeAs are 204 K using the new model, 421 K using MFA, and 385 K using the new model, 1627 K using MFA, respectively. As exchange-correlation potential, MBJ and MBJ + U provide a better description of the electronic and magnetic properties of ZrCoMnAs and ZrCoFeAs compounds. Important optical properties such as dielectric function, absorption coefficient, refractive index, optical conductivity, reflectivity, and electron energy loss function are calculated in the infrared, visible, and ultraviolet range. The static dielectric function suggests that ZrCoMnAs possesses greater polarizability. Both alloys exhibit similar behavior in the far ultraviolet region range and reach a maximum absorption in the ultraviolet range. The half-metallic character of both alloys is revealed from the reflectivity at zero frequency. The calculation of the thermoelectric properties shows positive Seebeck coefficients, indicating that these Heuslers are p-type. Furthermore, the highest power factor is observed at a temperature of 1400 K. The maximum value of ZT is ∼1.1 at 1400 K for ZrCoFeAs and ZrCoMnAs. These studies show that these alloys may have potential applications in the thermoelectric applications.

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.

Evidence of half-metallicity and multiferroic characters of tetragonal BaTi0.875Fe0.125O3: DFT-based calculation

In this paper, we discuss significant results obtained in both electronic and magnetic properties when the insulator, non magnetic but ferroelectric tetragonal oxyde perovskite BaTiO3 is modified by the substitution of an iron atom among 8 Ti atoms so that Fe content x = 0.125; our new material is BaTi0.875Fe0.125O3, hereafter referred to as TBTFO. Explicetely, we will use density functional theory (DFT) to show that tetragonal BaTi0.875Fe0.125O3 acquires a half-metal ferromagnetic character, with a net integer magnetic moment of 4.0 μB, along with an intrinsic polarization although reduced by 39 % when compared to the host material BaTiO3. This is an important result since the new material is presenting both ferroelectricity and ferromagnetism, i.e. multiferroelectricity. So it belongs to a very limted class of materials called multiferroics and giving up to a precious material suitable for opening up the application field of spintronics.

High Curie temperature Heusler alloys RhMnCrZ (Z = Si, Ge) investigated by DFT and Monte Carlo methods

We utilize density functional theory (DFT) to conduct a comprehensive theoretical investigation of the quaternary RhMnCrZ (Z = Si, Ge) Heusler alloys. Our study focuse on analyzing the stability, electronic structure, magnetism, exchange interaction, and Curie temperature of these alloys. The stability of the alloys is verified by calculating and analyzing the formation energy, phonon spectrum, elastic constants, and melting temperature. The calculation results show that the alloys are natural half-metallic ferromagnets with lattice constants of 5.868 Å for RhMnCrSi and 5.980 Å for RhMnCrGe. Meanwhile, the effects of compression and expansion stress on the half-metallic property are simulated from a practical perspective. The magnetic calculation of the alloys shows an integer magnetic moment and adheres to the Slater-Pauling rule, which states that Mt=Zt-24. Based on crystal field theory, orbital hybridization theory, exchange interaction, etc., the coupling effect of electrons and the principle of integer magnetic moments are analyzed. The Heisenberg model is used to calculate the exchange interactions between all atoms. Various exchange interactions between atoms are analyzed, and it is concluded that the dominant mechanism is the ferrimagnetic ordered phase. What’s more, we calculate the Curie temperature of the RhMnCrZ (Z = Si, Ge) alloys, taking into account the exchange interactions. The Curie temperatures of both Heusler alloys are above 900 K, which is significantly higher than room temperature. RhMnCrZ (Z = Si, Ge) alloys show promise for spintronics applications, as indicated by theoretical simulation calculations.

Half Metallic Properties of the Polymorphs of Rubidium Selenide Compound

Half-metallic ferromagnets denote a specific category of compounds where one spin channel exhibits a gap at the Fermi level, contrasting with the metallic nature of the other spin channel. This distinction results in complete carrier spin polarization, reaching 100% at the Fermi level. A first-principles pseudopotential plane-wave method is utilized to examine the structural, electronic, and magnetic characteristics of RbSe across various polymorphs. Our investigation covers the RbSe compound in the CsCl (B2), NaCl (B1), ZnS (B3), NiAs (B81) and wurtzite (B4) phases. The calculations were done using the quantum ESPRESSO code within the generalized gradient approximation. The lattice parameters, bulk moduli, and their pressure derivatives agrees with prior theoretical data for cubic structures. The electronic band structures and density of states indicate the emergence of half-metallic and magnetic properties in RbSe, which stem from the existence of spin-polarized p orbitals within the Se atom. RbSe shows half-metallic behaviour in all structures studied with an integer magnetic moment of 1μB per formula unit for CsCl, NaCl, ZnS; and 2μB for NiAs and wurtzite. Results showed that most energetically stable phase of all five crystal structures studied is the CsCl-type of RbSe.

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.

Half-metallic ferromagnetism in double perovskites Pb2XX'O6 (X = V and Cr and X’ = Zr and Hf)

The structural, magnetic, and electronic properties of Pb-based double perovskite, Pb2XX'O6 (X = V and Cr and X’ = Zr and Hf), have been studied in this paper. This study uses the first-principal projector augmented wave (PAW) potential within the generalized gradient approximation (GGA) as well as considering the on-site Coulomb re-pulsive interaction (GGA+U). The structure of these Pb-based double perovskite is calculated with four magnetic states, antiferromagnetic (AFM), ferromagnetic (FM), ferrimagnetic (FiM), nonmagnetic (NM), and then we compare the energy of these states to find the most stable state. We quickly discovered that all these materials have a lower energy level at the ferromagnetic state, especially Pb2VZrO6 which has an energy difference between AFM and FM state of 120 meV. By analyzing the density of states (DOS) and its magnetic moment, we further discovered that all these materials are half-metallic ferromagnetic (HM-FM). They have an integer magnetic moment because all these materials have a band gap in the spin-down channel. Under GGA + U, the band gap still exists and enlarges, and the V series materials became more stable because of the larger differences between the state of AFM and FM, while the Cr series have the opposite. Lastly, we calculate the electron configuration of V, Cr, Zr, and Hf under GGA and GGA + U calculations in this paper. The HM characteristics of the band gap in one of its spin channels and its ferromagnetic nature mean that there are huge potential applications of these new compounds in spintronics.

Structural, magnetic, and optoelectronic properties of rock salt MgO co-doped with Eu-TM (TM = Cu, Ag, and Au) for spintronic and UV detector applications: SP-DFT investigations

This study analyzes how adding europium and transition metals (Cu, Ag, and Au) at a 12.5% concentration to magnesium oxide (MgO) affects its physical characteristics and potential uses. To do so, the full potential linearized augmented plane wave (FP-LAPW) method, based on spin-polarized density functional theory (SP-DFT), is used to derive the results. Wu and Cohen’s generalized gradient approximation (GGA-WC) described the exchange-correlation potential. The modified Becke-Johnson exchange potential (TB-mBJ) was also used to improve the findings of optoelectronic properties. When Eu and TM (Cu, Ag, and Au) impurities are co-doped into the nonmagnetic (NM) semiconductor MgO, the structural optimization results show that the lattice constants increase, and the bulk modulus decreases with increasing the atomic number of transition metals. The resulting dilute magnetic oxides (DMOs) are stable in the spin-polarized ferromagnetic (FM) phase, and the formation energy values confirm their stability in the [Formula: see text] cubic structure, with the lowest value belonging to Eu[Formula: see text]TM[Formula: see text]Mg[Formula: see text]O. Similarly, calculations of electronic properties using the WC-mBJ functional demonstrate that all compounds have an indirect half-metallic bandgap at L-[Formula: see text] equal to 2.53, 2.49, and 1.39 eV for Eu[Formula: see text]Cu[Formula: see text]Mg[Formula: see text]O, Eu[Formula: see text]Ag[Formula: see text]Mg[Formula: see text]O, and Eu[Formula: see text]Au[Formula: see text]Mg[Formula: see text]O, respectively. They have an integer magnetic moment of 6 [Formula: see text]. The density of states shows that at the Fermi level, the 4f-Eu, d-TM, and p-O states give rise to new energy levels. This indicates that the f–p–d hybridization provides this system with its FM properties. Also, these compounds’ dielectric function and absorption spectra are calculated and analyzed to learn more about their optical properties. The results provide insight into the optical behavior of the materials. It is observed that the co-doped compounds exhibit greater optical absorbance than their un-doped MgO counterparts do. This theoretical investigation opens the way to preparing high magnetic moment DMOs using TM and rare earth as dopants suitable for spintronic and UV devices.

Influence of main-group elements on structural, electronic, magnetic and half-metallic properties of DO3-type Mn3Z (Z = Al, Ga, In, Si, Ge, Sn, P, As and Sb) alloys - A DFT study

We investigate the influence of main-group elements belonging to group III (Al, Ga and In), IV (Si, Ge and Sn) and V (P, As and Sb) on structural, electronic, magnetic and half-metallic (HM) properties of DO3-type Mn3Z alloys using density functional theory (DFT). In particular, we emphasize on the correlation between structural parameters (lattice constant) and the changes in electronic and magnetic properties of Mn3Z alloys. From full geometry optimization results, we find that the entire Mn3Z alloys stabilized to ferrimagnetic ordering. Further, the spin-polarized density of states (DOS) calculation reveals that Mn3Z (Z = Al, Si, Ge, Sn, As and Sb), Mn3Ga and Mn3In alloys exhibit, respectively, half-metallic (HM), nearly half-metallic (NHM) and metallic nature. While, the Mn3P alloy displays spin-gapless semiconducting (SGS) feature, in which spin-up and spin-down channels show metallic and spin-gapless feature, respectively. The Mn3Al, Mn3Z (Z = Si, Ge and Sn) and Mn3Z (Z = P, As and Sb) alloys follow Slater-Pauling rule well, and gives 100 % spin-polarization at the Fermi energy (EF) with total integer magnetic moment of 0, 1 and 2 μB/f.u, respectively. The contribution to total magnetic moment in all the Mn3Z alloys comes predominantly from Mn(Y) atoms. The molecular orbital (MO) hybridization mechanism is proposed to rationalize the HM band gap.

Structural stability, opto-electronic, magnetic and thermoelectric properties of half-metallic ferromagnets quaternary Heusler alloys CoFeXAs (X = Mn, Cr and V)

The Quaternary Heusler alloys CoFeXAs (X = Cr, Mn and V) fully spin-polarized with half-metallic stability, show low direct band gap, high absorption in the ultraviolet light, high spin polarization and adequate Seebeck coefficient. CoFeCrAs, CoFeMnAs and CoFeVAs have an integer magnetic moment of 4 μB, 5 μB and 3 μB according to the Slater-Pauling rule. The obtained minimal energy favors the type I CoFeVAs alloy over the type III CoFeCrAs and CoFeMnAs alloys. For CoFeCrAs and CoFeMnAs alloys, there is no band gap close to the Fermi level in the minority-spin, suggesting that they are direct Г–Г band gap semiconductors. Three-dimensional Co, Fe, and Mn atoms hybridized strongly, with little input from V and As atoms. Co, Fe, Cr, and Mn all have parallel magnetic moments, which results in ferromagnetic interactions between these atoms and gives these elements their ferromagnetic character.

Theoretical investigation of half-Heusler compound XYZ (X=Li, Na, K; Y=Ba; Z=B) for spintronic and thermoelectric applications

Density functional theory with pesudo potential approximation is used to study XBaB ([Formula: see text], Na, K) half-Heusler compounds structural, magnetic and electrical property using Quantum espresso code and thermoelectric properties were studied using BoltzTrap code. Total energy calculations were carried out in the [Formula: see text], [Formula: see text] and [Formula: see text] phases of XBaB compounds in [Formula: see text] type structure. The compounds were stable in [Formula: see text]-phase and hence further calculations were focused only on [Formula: see text] phase. From the spin polarization calculations, magnetic state was stable than nonmagnetic state and exhibits ferromagnetism at the equilibrium lattice constant with an integer magnetic moment of 2 [Formula: see text]. From the band structure calculations and through density of states, all the three compounds exhibit half-metallicity with 100% spin polarization by showing semi-conductivity for majority spin and metallicity for minority spin. In addition, thermoelectric properties were investigated for all three compounds. LiBaB is found to have high Seebeck coefficient of 2462[Formula: see text][Formula: see text]VK[Formula: see text] and ZT value of 1, compared to other compounds. These materials were found to have high ZT value and hence they can be used for thermoelectric applications.

Half-metallic ferromagnetism and thermoelectric effect in spinel chalcogenides SrX2S4 (X = Mn, Fe, Co) for spintronics and energy harvesting

Spintronics is an emerging technology in advanced quantum electronics, which has multidirectional applications. In this study, the electronic, magnetic, and thermoelectric characteristics of SrX2S4 (X = Mn, Fe, Co) are computed systematically. The stability in ferromagnetic states is verified by energy released from optimized structures and enthalpy of formation. The Heisenberg model is applied for Curie temperature. The band structures are plotted for both spin ↑ and ↓ configurations, which ensure 100% spin polarization and integer magnetic moments. Furthermore, the metallic behavior in spin ↑ and insulating behavior in spin ↓ confirm half-metallic ferromagnetism. The crystal field energy, direct exchange energy, indirect exchange energy, and exchange constants indicate that ferromagnetism is due to spin of electrons rather than any clusters of transition metals. The effect of thermoelectric parameters on spin functionality of electrons is addressed to enhance the device reliability. The thermoelectric performance is reported by power factor in the temperature span 100–500 K, which is important for energy harvesting.

Interplay of electronic structure and magnetism in Fe2 - and Rh2 -based Heusler alloys

In this work, we present a comparative study of the structural, elastic, electronic, magnetic, and transport properties of Heusler alloys ${\mathrm{Fe}}_{2}\mathrm{Rh}Z$ and ${\mathrm{Rh}}_{2}\mathrm{Fe}Z$ with $Z=\mathrm{Al}$, Si, Ga, Ge, In, Sn using the density functional theory. The strongly constrained and appropriately normed functional is considered for the exchange-correlation functional. The newly Heusler T-type pseudocubic structures, ${\mathrm{T}}^{p}$ and ${\mathrm{T}}^{c}$, with alternating layers and columns of Fe and Rh along the [001] direction being $\ensuremath{\approx}26$ meV/atom lower in energy than the inverse XA structure are predicted as ground states for the ${\mathrm{Fe}}_{2}\mathrm{Rh}Z$ family. According to the convex hull analysis, all the considered alloys are thermodynamically and mechanically stable or meta-stable. Hybridization schemes and their role in the formation of half-metallicity depending on the weak tetragonal distortion are discussed. XA-${\mathrm{Fe}}_{2}\mathrm{RhSi}$ is only predicted to be half-metallic in the minority channel with $100%$ spin polarization and integer magnetic moment of $5{\ensuremath{\mu}}_{B}$, while the ground state T structure with layered ordering of Fe and Rh is characterized by the $73%$ polarization due to a pseudogap around Fermi level. Additionally, a large Seebeck coefficient and figure of merit for the spin-down channel of XA-${\mathrm{Fe}}_{2}\mathrm{RhSi}$ is predicted.

On the Possible Half-Metallic Properties of Fe2RhZ (Z = Al, Si, Ga, Ge, In, Sn) Ferromagnetic Heusler Alloys

The possible presence of half-metallic properties in Fe2RhZ (Z = Al, Si, Ga, Ge, In, Sn) ferromagnetic Heusler alloys is ab initio studied. The calculation is carried out taking into account the exchange correlation effects using the generalized and meta-generalized gradient approximations. It is shown that the ground state of most investigated alloys is ferromagnetic ordering in the Тр model lattice. An analysis of the phase stability of the alloys showed that, in the considered approximations, most of them are stable in both the regular and inverse lattice, as well as in the three model lattices belonging to inverse-type Heusler structures with different atomic orders. It was predicted using the strongly constrained and appropriately normed (SCAN) functional that the Fe2RhSi alloy can exhibit the properties of half-metals, since it has an integer magnetic moment, a fairly high degree of polarization, and an energy gap at the Fermi level of spinup electrons.

First-principles study on novel Fe-based quaternary Heusler alloys, with robust half-metallic, thermoelectric and optical properties.

This work aims are studying new and unique Fe-based quaternary Heusler alloys for data storage, energy conversion and optoelectronics applications. The structural, magnetic, mechanical, electrical, thermal, and optical properties of novel FeCrYZ (Y = Ti, Zr, & Hf and Z = Sn, and Sb) alloys have been theoretically explored making use of density functional theory (DFT). Except for FeCrHfSb, all the alloys are found to exhibit a stable ferromagnetic ground state during the energy minimization process, also half metallic ferromagnetism exhibiting 100% spin-polarization at the Fermi level obeying Slater-Pauling rule with total integer magnetic moments of 2.00μ B and 1.00μ B respectively. FeCrTiSn, FeCrTiSb and FeCrZrSb alloys have mechanical and dynamical stability under ambient conditions. Boltzmann transport theory was used to investigate the thermoelectric performance of the materials in the temperature range of 100-900 K. The estimated dimensionless figure of merit (ZT) for FeCrTiSb is 1.76, FeCrZrSb is 0.61, and FeCrHfSb is 0.86 at 900 K. Optical spectra reveal that absorption occurs across the visible and near UV ranges of the region. Results show that the narrow bandgap, spin polarization and high ZT value of FeCrTiSb make it a promising candidate for spintronic, thermoelectric and optoelectronic applications.