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Spintronic is the developing technology which probes the properties of quantum devices with spin of electrons which reduce the size and enhance its speed. Therefore, here the role of 5d electrons and thermoelectric characteristics of double perovskites (DPs) K 2 ZCl/Br 6 (Z = Ta, W, Re) elaborated comprehensively by density functional theory (DFT). The Heisenberg model spin polarization density (SP) has been applied to evaluate the Curie temperature (T c) and spin polarization factor. The tolerance factor (t F) and formation energy (ΔH) have been calculated to confirm the stability of structures. Ferromagnetism has been discussed in terms of spin polarization, crystal field energy (Δ CF) and exchange energies (Δ(d), Δ(pd)). The double exchange mechanism, and exchange constants ensure the role of electrons spin in ferromagnetism instead of segregation of transition metal ions. The transferring of magnetic moments of transitions metals to nonmagnetic sites (K, Cl, Br) show the exchange of spin of electrons and integer values of total magnetic moment show 100 % spin polarization. Finally, the transport properties are studied in standings of electrical and thermal conductivities. The large value of Seebeck coefficient and power factor ensure the importance of studied DPs for thermoelectric generators. • Spintronic and energy harvesting applications. • Large value of Curie temperature and high spin polarization. • The ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism evidence complete spin polarization. • Ultralow low values of thermal conductivity and Large power factor. [ABSTRACT FROM AUTHOR]

In this study, the half-metallic behavior and magnetic properties of various (001) surfaces for Y 2 CrSn Heusler alloy were investigated using the spin-polarized first-principles method. The spin polarizations of the standard stable YSn-terminated and artificial stable SnSn-terminated (001) surfaces were −96.9% and −95.8%, respectively, using the generalized gradient approximation (GGA) method (−69.2% and −83.0% using the GGA + U method), and thus the two surfaces have potential use in spintronic devices. The spin polarizations of the standard YCr-terminated, artificial YY-terminated, and artificial CrCr-terminated (001) surfaces were only −43.0%, 29.3%, and −40.8%, respectively, using the GGA method (−63.2%, −67.9%, and −44.4% using the GGA + U method). The atomic magnetic moments (AMMs) of the Y and Cr atoms in the outmost layer changed greatly due to the surface states, but little change was found in the AMMs of atoms near the central layer. The average AMMs obtained for the Sn, Y, and Cr atoms using the GGA + U method were only slightly larger than the corresponding AMMs determined using the GGA method. Image 1 • Spin polarizations of stable YSn and SnSn-term (001) surfaces were high. • Spin polarizations of unstable YCr, YY, and CrCr-term (001) surfaces were low. • Atomic magnetic moments of Y and Cr atoms changed little in the outermost layer. • Little change in atomic magnetic moments of atoms near the central layer. [ABSTRACT FROM AUTHOR]

A succinct summary of various physical characteristics of halide double perovskites Cs 2 KXCl 6 : (X = Ti and V) has been summarized using Density Functional Theory (DFT), as applied in WIEN2k simulation code. These material's stability in Fm-3 m cubic symmetry is confirmed by structural optimization, tolerance factor and elastic parameters. The electronic band structures and density of states calculated using GGA and G G A + m B J show that these materials are semiconducting in spin down channels. The crystal field splitting of d-orbitals is used to explain the semiconducting ferromagnetic nature of these Ti- and V- based halide double perovskites. The ferromagnetic character of these double perovskites is suggested by the optimization and asymmetric DOS across Fermi level. We have also discussed about the origins of half-metallic bandgap and magnetism. The total magnetic moments of the Ti and V-based double perovskites are 1 μ B and 2 μ B, respectively, with the transition metal atoms (Ti/V) accounting for the major contributions. At the Fermi level, these double perovskites have 100% spin polarization, indicating that they could be used in spintronics. • The DFT studies confirm the structural stability of double perovskites(DPs) Cs 2 KXCl 6 : X = Ti, V in ferromagnetic state at low temperature. • Structural optimization and tolerance factor confirms the structural stability of the DPs. • The DPs shows half-metallic nature in both GGA and mBJ calculations. The half-metallic character of the DPs is also supported by their integral magnetic moments. • The mechanical parameters shows Cs 2 KVCl 6 as brittle while as Cs 2 KTiCl 6 as ductile. • These DPs exhibit 100% spin polarization at the Fermi level suggests that they might be used in spintronics. • The findings may be beneficial for experimentalists to prepare these type of DPs in laboratories for commercial uses. [ABSTRACT FROM AUTHOR]

Recent progress in spin caloritronics has boosted exploration of materials for their application in this novel field. Heusler alloys which were being hailed as thermoelectric and magnetic materials have seen uprise for their suitable properties however lack of studies featuring good coupling between magnetic and thermoelectric properties have seen little impact in the field of spin-caloritronics. Present work explored doping of transition metal in a thermoelectric half-Heusler alloys NbCoSb on Nb site to induce spin-polarization and spin-dependent transport properties. Co (Mn) doping results in 98.09% (19.38%) negative spin polarization and 0.51 μ B /f.u. (1.98 μ B /f.u.) magnetic moment. Magnetic exchange parameter shows presence of long range RKKY-type interaction in Co and Mn doped NbCoSb. On one-hand, doping of Co and Mn in NbCoSb suppressed the electronic transport properties whereas, on the other hand spin dependent Seebeck effect is introduced. The synergistic effect of magnetic and thermoelectric properties in non-magnetic NbCoSb via doping of Mn and Co shows large variation in the value of Seebeck coefficient, electrical conductivity and electronic thermal conductivity with flipping of spin-directions suggests Co rich NbCoSb as a promising candidate for spin-caloritronics application. • Well known thermoelectric half-Heusler alloy NbCoSb is studied for spin-caloritronics. • Magnetism is induced in NbCoSb with Co and Mn doping. • High spin polarization and spin dependent Seebeck effect is introduced with Co doping. • Synergistic effect of thermoelectric and magnetic properties are reported. [ABSTRACT FROM AUTHOR]

The spin polarized electronic band structures, density of states (DOS) and magnetic properties of Mn 2 WSn, Fe 2 YSn (Y=Ti, V), Co 2 YSn (Y=Ti, Zr, Hf, V, Mn) and Ni 2 YSn (Y=Ti, Zr, Hf, V, Mn) huesler compounds are reported. The calculations are performed by using full-potential linearized augmented plane wave method (FP-LAPW) within density functional theory. The magnetic trend in these compounds is studied using values of magnetic moments, exchange interaction and calculated band gap. The results reveal that Mn 2 WSn and Ni 2 VSn show 100% spin polarization, Co 2 YSn (Y=Ti, Zr, Hf, Mn), Fe 2 YSn (Y=Ti, V), and Ni 2 MnSn exhibit metallic nature and Ni 2 YSn (Y=Ti, Zr, Hf) and Co 2 VSn show semi-conducting behavior. [ABSTRACT FROM AUTHOR]

A first-principles theoretical study of the enhanced electronic and magnetic properties of a single-layer CdS (denoted as SL-CdS) was conducted via Li substitutional doping at possible sites. Previous work shows that SL-CdS is a non-magnetic and direct bandgap semiconductor. Our work demonstrated that electronic bandgap tuned to smaller and larger values, e.g., the calculated bandgap (pseudo bandgap) for Li Cd (Li h) are 1.80 eV and 1.62 eV, respectively. Local magnetic moment induced via Li atomic doping at possible dopants sites except for Li h. The Li Cd gives a maximum magnetic moment of 0.98 μ B and shows the half-metallic character with a small dispersion for the spin-down channel at the Γ point. Among all the possible sites, the Li Cd in SL-CdS is magnetic and being most favorable thermodynamically under both S-rich and Cd-rich conditions. The Li Cd in SL-CdS indicates spin polarization with increased bandgap for spin-up and spin-down channels. In contrast, the Li S induces a magnetic moment of 0.86 μ B with a reduced bandgap of 0.60 eV for both the spin-up and spin-down channels. The partial magnetic moment is due to the fact small concentration of the dopant. Interestingly, Li h in SL-CdS shows non-magnetic semiconducting nature with decreased bandgap. For further investigation, we considered the most favorable Cd-Site. For room-temperature ferromagnetism, we did ferromagnetic and anti-ferromagnetic calculations. We considered interactions between two Li atoms substituted at far positions (1, 2) and near positions (1, 3) in SL-CdS. It was found that 2Li Cd in SL-CdS at near positions (1, 3) has FM order with Curie temperature (T c) of 339.95 K at − 5 % compressive biaxial strain. The effect of Li doping on electronic and magnetic properties of SL-CdS can help to utilize SL-CdS materials in electronics and spintronics devices applications. • We select nitrogen (Li) as a first-row element that could host spin-polarized electrons in its s-orbitals as possible sources of magnetic moment, and study various possible dopant positions. • The main aims of our study are (i) tuning of the electronic bandgap (ii) inducing magnetic moments in diamagnetic single-layer CdS. • Studying ferromagnetic (FM) and antiferromagnetic (AFM) coupling to predict the more favorable state. • Our material shows three simultaneous properties of ferromagnetism, diamagnetism and semiconducting one. • To the best of our knowledge, no 2D material is predicted to have such high temperature stability of these properties to-date. [ABSTRACT FROM AUTHOR]