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The weak magnetic properties of Ni 0.25 NbSe 2 are attributed to the delocalized nature of Ni-3 d electrons and hence poor spin polarization. [Display omitted] • Ni x NbSe 2 with x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25 were synthesized and observed that Ni intercalation limit is 25 %, beyond which NiSe phase segregates. • A phase transition is observed beyond x = 0.20 in Ni x NbSe 2 with a 2 a o × 2 a o × 1 c o order superstructure. • Theoretical calculation on Ni 0.25 NbSe 2 shows that the magnetic spins are very weakly spin-polarized and the Ni-3 d states are more delocalized. • Magnetic measurements on Ni x NbSe 2 (x = 0.05, 0.1, 0.2, 0.25) shows very small magnetic moment at low temperature for all the compounds attributed to the delocalized nature of Ni-3 d electrons, which is conformed from the theoretical studies. The article presents the synthesis, structural and magnetic properties of Ni x NbSe 2 (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25). The intercalation limit of Ni in NbSe 2 is found to be 25 mol%, above which NiSe appears as a binary impurity phase. Single crystal X-ray diffraction studies show that all the compounds crystallize in the hexagonal P6 3 /mmc space group. However, there is a distinct phase transition beyond x = 0.20 with Ni intercalation in Ni x NbSe 2. The Ni x NbSe 2 compounds crystallized in the parent 2H phase with x value between 0 ≤ x ≤ 0.2. Subsequently, the phase transforms into the 2H(I) phase with an order superstructure of 2 a o × 2 a o × 1 c o for 0.20 ≤ x ≤ 0.25 in Ni x NbSe 2. The superstructure formation is attributed to the occupation of Ni at the alternate octahedral voids present in the van der Waals gap of the NbSe 2. The XPS results and theoretical analysis clearly show that the intercalation of Ni results in a more metallic character in Ni x NbSe 2. Magnetic measurements on Ni x NbSe 2 (x = 0.05, 0.1, 0.2, 0.25) shows very small magnetic moment at low temperature for all the compounds. Theoretical calculation on Ni 0.25 NbSe 2 shows that the Ni-3 d electrons are delocalized and are very weakly spin-polarized, which may be the reason for the experimentally observed weak magnetism in these compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • We study conductance and polarization in borophene magnetic junctions, theoretically. • The transmission probability can be is zero for most angles of incident electron. • Spin/valley polarization can be easily changed by the external magnetic field. • An 8- Pmmn borophene magnetic junctions can be used as an effective spin filter. • Full valley polarization can be achieved in an 8- Pmmn borophene magnetic junctions. Conductance, spin and valley polarizations through 8- Pmmn borophene barriers in the presence of external Rashba spin–orbit interaction (RSOI) and magnetic field are investigated theoretically. The spin-dependent conductance shows a strong dependence on the direction of the 8- Pmmn borophene barriers, the strength of RSOI and value of the magnetic field strength. For two barriers unlike to one barrier, the spin-dependent conductance exhibits a prominent oscillatory behavior. For the parallel configuration, the dependence of conductance on the magnetic field is more than for the antiparallel configuration. Transmission probability without and with spin rotation decreases drastically with the increase in the value of the magnetic field, so that for sufficiently large magnetic fields, the transmission probability is zero for most electron incidence angles. The size and direction of the spin and valley polarization can be tuned by the strength of RSOI, direction of the 8- Pmmn borophene barriers, size of the magnetic field and type of parallel or antiparallel configuration. In certain conditions, full valley polarization can be achieved in the proposed structure. [ABSTRACT FROM AUTHOR]

[Display omitted] Incorporating magnetic species, magnetic functional groups or additives, into polymer hosts is an effective method for synthesizing magnetic polymers. Polymers can gain magnetic moments not solely through magnetic coupling but also via the induction of Coulombic excitation. Attachment of the magnetic side-groups to the polymer backbone increases orbital localization in repeat units. This will bring two competing effects. The orbital localization will increase the intra-site Coulomb interaction, which increases magnetic moments in repeat units. Oppositely, the orbital localization also increases the energy splitting between orbitals on the polymer backbone and on side-groups, suppressing thus the magnetic moments of repeat units. However, a preference for low-spin states in the polymer units emerges when a substantial split in orbital energy occurs due to a strong coupling, consequently suppressing the magnetic moment. On the contrary, a minimal split in orbital energy within the polymer units can readily induce a high-spin state and generate a magnetic moment. However, in such cases, the Coulomb interaction triggered by the interconnected magnetic moieties might be too weak to produce a magnetic moment in the polymer. To explore this trade-off, we have proposed a theoretical two-level model aimed at elucidating the decision-making process of experimentalists during the synthesis of magnetic polymers. We also found that the dimerization of the polymer backbone together with the phonon dependence of spin–spin interaction between near-neighbor repeat units increases magnetic moments. As the magnetic responses arising from Coulombic interactions in polymers are intricately linked to carrier density, properties of the magnetic polymers acting as an active layer of a field-effect transistor can be tuned by the gate field, which controls the charge carrier density in the transistor transport channel. [ABSTRACT FROM AUTHOR]

• We explore 2D systems with a type of spin-polarized nodal loop that are robust under SOC and characteristic an hourglass type dispersion. • γ -structure VCl 2 , which bridges hourglass loop materials and spintronics, exhibits many unique properties including large spin polarization and robust topological properties. • Most importantly, hourglass loop is intrinsic and do not require any external conditions in experiments such as strain, magnetic field, or electric field. Hourglass loop in two-dimensional (2D) systems is typically vulnerable against spin–orbit coupling (SOC). Here, we explore 2D systems with a type of spin-polarized nodal loop that is robust under SOC and characteristic of an hourglass-type dispersion. Through first-principles calculations, we identify the monolayer VCl 2 materials as a realistic material platform to realize an hourglass loop. There exist three phases, all of which are dynamically stable. For the γ -structure, as a new single spin hourglass loop material. It shows semiconducting and gapless properties in spin down and spin up channels, respectively. Moreover, it always exhibits an hourglass loop property in the absence and presence of SOC. It indicates that the hourglass has strong against SOC. Our work suggests a realistic material platform for investigating the novel physics associated with band crossings in 2D systems. [ABSTRACT FROM AUTHOR]

• Spin transport properties in bilayer graphene on a Cr 2 X 2 Te 6 monolayer (where X = Ge, Si, or Sn). • Employment of a Hamiltonian model to describe carrier motion in the bilayer graphene/ Cr 2 X 2 Te 6 system. • Study of spin transport, demonstrating the modulation of spin polarization from 0% to 100% by varying gate voltage. • Perfect spin polarization switching from −100 % to + 100 % through gate voltage adjustment, achieving complete spin filtering. • Unique spin conductance curve splitting under perpendicular electric field, showing potential for spintronic applications. We investigate the spin transport properties of bilayer graphene grown on a monolayer Cr 2 X 2 Te 6 hybrid structure. Here, X can be Ge, Si, or Sn, all of which are van der Waals layered materials with magnetic properties. Our results show that the magnetism in bilayer graphene is layer-dependent, affecting the spin-dependent energy gap and Fermi level. Focusing specifically on the X = Ge case, we reveal that pure spin currents can be precisely controlled by applying gate voltage and a perpendicular electric field across the barrier. By varying these parameters, we achieve perfect switching of pure spin current from spin-down to spin-up due to the system's layer-dependent magnetism. Moreover, due to differing gaps between spin-up and spin-down electrons, spin polarization can sharply jump from 0 % to 100 % with changes in gate voltage. The splitting of spin conductance curves, creating a fully functional spin-filtering junction, is also predicted under a varying perpendicular electric field. This model can be extended to cases where X is Si or Sn due to their similar electronic band structures. Our research demonstrates the potential of bilayer graphene on Cr 2 X 2 Te 6 hybrid structures, which exhibit distinctive layer-dependent magnetism ideal for spintronic applications. [ABSTRACT FROM AUTHOR]

Rhenium-based double perovskite oxides (DPOs) are a particularly fascinating class of materials because of high carrier spin polarization, large magnetic anisotropy energy (MAE), and complex electrical behavior along with high Curie temperature (T C). Herein, we discussed the impact of biaxial ([110]) strain ranging from − 5% to ＋ 5% along the a b -plane on the electronic and magnetic properties of CaCuFeReO 6 (CCFRO) DPO using a b - i n i t o calculations. The unstrained system exhibits a ferrimagnetic (FiM) spin ordering as an energetically stable magnetic ground state due to electron hopping between Fe + 3 /Re + 5 t 2 g and Cu + 2 e g orbitals along with a metallic electronic state. Moreover, [010] (b -axis) is the magnetic easy axis that produces the MAE of 5.36 meV, giving a giant MAE constant of 1.97 × 1 0 7 erg/cm 3. The evaluated partial spin-magnetic moment on the Cu1/Cu2/Fe/Re ion is 0.14/0.44/4.04/ − 0. 64 μ B , where " − " sign on the Re moment means that its spin is antiparallel to the other ions, verifying the FiM ordering in the system. Also, the e g , t 2 g / e g , and t 2 g orbital characteristics of Cu + 2 , Fe + 3 , and Re + 5 ions are visible in the spin-magnetization density iso-surfaces plots, respectively. Using the classical Heisenberg model, the computed T C for the unstrained structure is 576 K, which is quite close to the experimentally reported value of 567 K. In addition, it is shown that the FiM metallic behavior in the motif is robust against biaxial ([110]) strain within the considered range. It has also been revealed that T C increased to 5.73%/3.30% for the considered range of − 5% compressive/＋5% tensile strain due to improved structural distortions. [Display omitted] • A ferrimagnetic (FiM) state is found the energetically stable one. • [010] (b-axis) is the magnetic easy axis having MAE of 5.36 meV, giving a giant MAE constant of 1.97 × 107 erg/cm 3. • T C increased to 5.73%/3.30% for the considered range of −5% compressive/+5% tensile strain. [ABSTRACT FROM AUTHOR]

• The formation energy of Fe2+ in the β-Ga 2 O 3 matrix is lower than that of Fe3+, and the system is more stable when the Ga or O vacancies (V Ga or V O) are adjacent to the Fe lattice position. • The β-Ga 31 Fe2+/3+O 47 and β-Ga 30 Fe2+/3+O 48 systems all exhibit ferromagnetism with above-room-temperature Curie temperature. Ga 30 Fe2+/3+O 48 has more spin-polarized O atoms in the same direction. • The magnetism originates from the double-exchange interaction of the coupling and hybridization of the Fe-3d state of Fe3+ and the O-2p state. • Ga 30 Fe3+O 48 system achieves semi-metallization with 100 % hole spin polarization. Induced by the spin-polarized double-exchange interaction between the 3d orbitals of Fe atoms and O-2p orbitals near the O/Ga vacancy complexes, the origin of magnetism in β-Ga 2 O 3 is investigated by using geometry optimization and energy calculation based on the first-principles generalized gradient approximation Hubbard + U method of density-functional theory. The results show that the formation energy of Fe2+ in the β-Ga 2 O 3 matrix is lower than that of Fe3+, and the system is more stable when the Ga or O vacancies (V Ga or V O) are adjacent to the Fe lattice position. It is found that the β-Ga 31 Fe2+/3+O 47 and β-Ga 30 Fe2+/3+O 48 systems all exhibit ferromagnetism with above-room-temperature Curie temperature. β-Ga 30 Fe2+/3+O 48 (i.e., with Fe2+/3+ and V Ga) has more spin-polarized O atoms in the same direction. The magnetism originates from the double-exchange interaction of the coupling and hybridization of the Fe-3d state of Fe3+ and the O-2p state, which increases the magnetic moment of the β-Ga 30 Fe3+O 48 system. This study provides a theoretical reference for designing and preparing new β-Ga 2 O 3 -based dilute magnetic semiconductors and related spintronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

• First-principles calculations performed for XA and L2 1 phases across X 2 FeAl series. • The degree of d-d orbital hybridization drives magnetic and electronic properties. • Increasing X-site valence electron counts result in increased hybridization levels. • Orbital hybridization trends must be considered when predicting material properties. First-principles calculations are performed for full (L2 1) and inverse (XA) Heusler compounds X 2 FeAl, where X comprise a range of 3d (Sc, Ti, V, Cr), 4d (Y, Zr, Nb, Mo), and 5d (Hf, Ta, W) early and middle column transition metal elements. The formation energy difference between full and inverse phase and the degree of d-d orbital hybridization with increasing total valence electron count are shown to drive the magnetic properties (total and atomic magnetic moments, spin polarization) and electronic properties (band structure and projected density of states) of the material system. Specifically, X-site atomic magnetic moments take on increasingly Fe character with increasing valence electron count, in both full and inverse Heusler phases. This can be explained by changes on the degree of d-d hybridization between X- and Fe-site d orbitals. Synchronized energy shifts in the PDOS of the X- and Y-sites (Fe) across each of the full and inverse Heusler series provide us insight to controlling spin polarization via composition. This work demonstrates the need to holistically study the thermodynamic phase stability, magnetic moments, and spin polarization of Heusler alloys, in the framework of anti-site disorder and in a wider compositional context. The end goal of this study is to benefit the mapping of experimental results in search of a specific property, by providing a methodology for extrapolating properties based on experimental or theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, the charge and spin magneto coefficients of a double quantum dots system coupled in series connected to ferromagnetic electrodes with collinear magnetic alignments at finite bias voltage are theoretically investigated based on Green's functions in a linear response regime. Magneto and spin magneto thermopower are estimated as a function of the thermal gradient and quantum dot energy levels. Magneto conductance and spin magneto conductance are also studied. The results showed that the positions of the peaks can be controlled for each value of polarization, and the magneto conductance is negative where the charge conductance for parallel alignment is lesser than that for antiparallel alignment except in the case of high spin polarization and ferromagnetic spin exchange. Enhancing the magneto thermoelectric coefficients of double quantum dots is a promising step in creating adaptable magnetic switching for thermoelectric generations, which could find use in thermal energy-based logic circuits or heat control applications. [ABSTRACT FROM AUTHOR]

• The half metallicity of NiVTiZn 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. • The 100% spin polarization is preserved in V(Ti), Ni-Zn and V-Ti disordered structures. • The effect of various disorder on mechanical and thermodynamic properties is also studied in detail. 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. [ABSTRACT FROM AUTHOR]

A possibility of appearance of antiferromagnetic ordering in armchair carbon nanotubes and graphene is studied using density functional theory within a DFT+U approach. It is shown that the Coulomb repulsion between electrons in the π -orbitals of graphene would need to reach a threshold value of U c = 3. 6 eV , in order to stabilize the antiferromagnetic order and an energy gap in an electron spectrum at the Fermi level. In the carbon nanotubes the threshold value U c for appearance of the antiferromagnetism decreases with the nanotube's diameter. For an intermediate value of U < U c the dependence of the energy gap on the diameter of nanotube is well described by a power law in agreement with earlier experimental findings. The antiferromagnetism in the carbon nanotubes is suppressed by departure of the Fermi level from a neutrality point. The latter result can qualitatively explain experimentally observed gate voltage dependence of the energy gap in junctions with the suspended carbon nanotubes as well as the absence of the energy gap in junctions with nanotubes deposited on some substrates. • Carbon nanotubes (CNTs) under influence of gate voltage are studied with a DFT+U method. • Hubbard U stabilizes an antiferromagnetic order with a quasiparticle energy gap in the CNTs. • The computations explain observed gate voltage dependence of the gap in ultraclean CNTs. [ABSTRACT FROM AUTHOR]

• Property of multicomponent soft magnetic alloy was predicted by first-principles calculation. • Complex competition exists among Fe, Ni, and Cr in affecting physical properties. • Relatively high contents of Fe and Cr is expected for great electromagnetic performance. • Ni is beneficial to enhancing the system stability of the face-centered cubic structure. • This work give a strategy for accelerated design of multicomponent soft magnetic alloy. Multicomponent alloys (MCAs) exhibit excellent soft magnetic properties and other service performance, and are promising for high-end applications. However, their complicated effects of element mixture and low efficiency in research and development could limit their industrialization. Hence, in this work, first-principles calculation was conducted on the relative formation energy, magnetism and density of states of Fe-Ni-Cr-Si-P-B-C-Nb MCAs for predicting its alloy stability, saturation magnetization (B s) and electric resistivity (ρ). The calculation results mainly present the mixture effects among Fe, Ni and Cr. There is a complex competition among Fe, Ni, and Cr elements in affecting the physical properties of the MCAs. The magnetism of the MCAs is not only determined by composition of magnetic elements but also by the coordination environment around the magnetic atoms. To achieve both high B s and high ρ in the Fe-Ni-Cr-Si-P-B-C-Nb system, proper addition of Fe and Cr may be expected. The optimized MCA has a relatively high B s nearly equal to the Fe-Si-Al system, and exhibits higher ρ and higher spin polarization. This indicates that the proposed MCAs are promising for both power devices and spintronic applications. This work gives a strategy for the property prediction and accelerated design of MCAs by first-principles calculation. It has promising potential to explore other element systems as for high-performance soft magnetic MCAs. [ABSTRACT FROM AUTHOR]

We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state. • A topological insulator sandwiched between ferromagnetic layers is considered. • Two magnetization configurations of layers (parallel and antiparallel) are studied. • Switching between trivial and topological insulator state under gate voltage is discussed. [ABSTRACT FROM AUTHOR]

Bilinear magnetoresistance has been studied theoretically in 2D systems with isotropic cubic form of Rashba spin–orbit interaction. We have derived the effective spin–orbital field due to current-induced spin polarization and discussed its contribution to the unidirectional system response. The analyzed model can be applied to the semiconductor quantum wells as well as 2DEG at the surfaces and interfaces of perovskite oxides. • Magnetoresistance (MR) is studied in 2DEG with cubic Rashba spin-orbit interaction. • MR contains a term, that scales linearly with in-plane magnetic field and current. • Bilinear MR results from spin-orbital field due to current-induced spin polarization. [ABSTRACT FROM AUTHOR]

We theoretically study the influence of an external magnetic field on the transport properties of a double quantum dot (DQD)-Majorana nanowire system in a cross-shaped configuration with central dot coupled to a superconductor and normal metallic leads. In such a system, we can observe a subtle interplay between generation of Andreev bound states, Majorana mode leaking into quantum dots and interdots Fano-like interference processes. We show that properly selected side-coupled quantum dot energy can slow down/activate the process of Majorana mode leaking into DQD and additionally can strongly affect the differential and linear conductance in the considered system. We also study the influence of spin polarization of quantum dot–Majorana mode coupling on the transport properties of the considered system, especially on its linear conductance. • The theoretical model of a double quantum dot coupled to a Majorana nanowire system in a cross-shaped configuration is analyzed. • Strong competition between Majorana mode leaking into quantum dots and interdots Fano-like interference processes are observed. • The spin polarization of quantum dot–Majorana mode coupling affects the differential conductance. [ABSTRACT FROM AUTHOR]

• DFT calculations were used to study the magnetic properties of the Fe 2 MnAs alloy. • The influence of point defects on these properties were investigated. • The formation energy, density of states, and magnetic moments, were computed. • The contraction of the lattice enhance the spin polarization of the Fe 2 MnAs alloy. • The defects of Mn As , Mn ↔ As, V As , and V Mn exhibit 100% spin polarization. First-principles calculations within the framework of the density functional theory were conducted using the FP-LAPW method to investigate the electronic and magnetic properties of the Full-Heusler Fe 2 MnAs alloy. The study encompassed the examination of its perfect structure as well as the variation of lattice constants around the ground state. The negative value of the calculated formation energy suggests that the alloy may form spontaneously. From a magnetic perspective, Fe 2 MnAs exhibit a ferromagnetic order. The alloy also shows a high spin-polarization that may be increased, transforming the alloy into a half-metal, with the contraction of the lattice constant. Furthermore, the investigation delved into the effect of point defect formation. The calculated formation energies for vacancies, antisite, and exchange defects suggest the likely occurrence of some of these defects within the Fe 2 MnAs compound. Significantly, certain defects contribute to the spin-polarization of the alloy, effectively rendering it a fully half-metallic material. [ABSTRACT FROM AUTHOR]

• An effect of oxygen vacancy on the electronic and magnetic properties of copper pyrophosphate compound was investigated using DFT calculations. • The vacancy presence reduced the gap width from 2.17 eV to 0.19 eV, changing its character from indirect to direct. • The oxygen vacancies slightly modify the spin polarization of d-orbitals of Cu atoms neighboring the vacancy, resulting in the non-zero total magnetic moment of 0.19 µB/FU. The effect of oxygen vacancies (V O) on the electronic and magnetic properties of copper pyrophosphate dihydrate Cu 2 P 2 O 7 *2H 2 O (CuPPD) semiconductors is studied employing the DFT-based ab initio pseudopotential method. Site preference for vacancy formation on the selected oxygen sublattices is analyzed. Investigations revealed that the V O vacancies led to narrow bands of hybridized Cu-3d and O-2p states within the energy gap of perfect CuPPD semiconductors, significantly reducing the gap width from 2.17 eV to 0.19 eV and changing its character from indirect to direct one. Calculations have shown that the vacancies have no significant influence on the ferrimagnetic structure of CuPPD. The magnetic properties are driven by local magnetic moments of Cu atoms pointed oppositely. The oxygen vacancies slightly modify the spin polarization of d-orbitals of Cu atoms neighboring the vacancy, resulting in the non-zero total magnetic moment of 0.19 µ B /FU (0.0 µ B /FU in perfect CuPPD). The study's main finding, which can be exploited in nanoelectronics, is that the controlled implementation of oxygen vacancies can regulate the energy gap of CuPPD semiconductors. [ABSTRACT FROM AUTHOR]

The particles in the honeycomb lattice with on-site s -wave pairing exhibit many interesting behaviors, which can be described in the framework of the Hubbard model. Among others, at the half-filling, some critical value | U c | of pairing interaction U < 0 exists that, for U < U c , the superconducting phase becomes unstable. Introduction of the nonzero hopping t ′ between next-nearest-neighbor sites strongly modifies the physical properties of the system. Here, we discuss the behavior of the system for t ′ ≠ 0 (at the ground state), where the hopping between next-nearest neighbors leads to change of the order of phase transition between superconducting and normal phases from discontinuous to continuous one in the external magnetic field h. We show that this behavior is strongly dependent on t ′ and associated with the Dirac cones in the non-interacting band structure of the system. For non-zero magnetic field and for some range of t ′ , a spin-polarized superconducting phase occurs in the ground state phase diagram (only at the half-filling and for h ≠ 0). • Ground state of the Hubbard model in the external magnetic field is investigated. • Effects of the next-nearest-neighbor hopping are investigated on the honeycomb lattice. • Two different superconducting phases are found to be stable. • The spin-polarized superconducting (so-called Sarma) phase occurs in the field. • The ground state phase diagrams of the model are determined. [ABSTRACT FROM AUTHOR]

• A dynamical study at atomistic-scale on the behavior of non-collinear antiferromagnetic Mn 3 Pt driven by current-induced spin orbit torque. • Two different field-free magnetic excitation modes can be achieved in W/Mn 3 Pt heterostructures with varying crystalline direction. • Oscillation frequency depends on the injected current density as well as the antiferromagnetic layer's thickness. Current-induced spin–orbit torque (SOT) enables highly efficient manipulation of magnetic orders. Non-collinear antiferromagnets exhibit ultrafast spin dynamics by SOT with much higher oscillation frequency than ferromagnets, offering potential applications in terahertz spintronic devices. In this study, we used atomistic scale Landau-Lifshitz-Gilbert simulation approach to demonstrate different magnetic excitation modes in W/Mn 3 Pt heterostructures with varying crystalline direction. When the spin polarization is perpendicular to the Kagome plane of Mn 3 Pt, all the magnetic Mn atoms oscillate periodically within the Kagome plane around the normal direction. In contrast, when the spin polarization is parallel to the Kagome plane, only two neighboring Mn atoms rotate while another neighboring Mn atom remains immobile. Interestingly, both of these magnetic excitation modes have the same frequencies and occur in the terahertz range. Additionally, the frequency is proportional to current density and inversely proportional to the antiferromagnetic layer thickness. These findings provide a deeper understanding of magnetic excitation properties in non-collinear antiferromagnets, which can inform the design of terahertz spintronic devices. [ABSTRACT FROM AUTHOR]

ABO 3 perovskites oxides show fascinating functional properties, including ferroelectricity, magnetism, metal-to-insulator transition, half metallicity, polar metallic phase, etc. In particular, rare earth nickelates and alkaline earth nickelates within the orthorhombic crystal structures show an insulator–metal transition (IMT) and half-metallic (HM) nature respectively. Here, we report a series of ferromagnetic polar half metals by constructing LnNiO 3 /CaNiO 3 short period 1/1 superlattices (SLs) with Ln = La, Nd, Gd, Dy, Tm, and Lu within an orthorhombic phase. The polar distortion is induced by a hybrid-improper ferroelectric mechanism i.e., by constructing Ln/Ca layer-ordering. The system shows a ferromagnetic Ni-Ni interaction, whereas Ni-3 d 's are interacting antiferromagnetically with O-2 p. We explain that the origin of observed half metallicity and ferromagnetism is due to strong hybridization between Ni-3 d and O-2 p near the Fermi level and double exchange mechanism, respectively. • Ferromagnetic polar half-metals within LnNiO 3 /CaNiO 3 • Large spin polarization is expected. • Hole mediated double exchange mechanism drives the ferromagnetic ordering. • The systems exhibit polar nature through hybrid improper ferroelectric mechanism. • These systems are metallic due to strong hybridization between Ni-3 d and O-2 p. [ABSTRACT FROM AUTHOR]

• The effect of 3d TM dopants (12.5% doping concentration) in BiCoO 3 having C-type AFM arrangement has been studied using first principle calculation to study the structural, electronic and magnetic properties. • The defect states are introduced due to presence of 3d TM dopants in BCO. • The PDOS reveal that V, Ni and Zn doped BCO exhibit half metallic characteristics. • The net magnetization was found to arise due to TM doping at Co site which may be attributed to the uncompensated Co spins and is mainly localized on the TM dopant. • SSP model was used to explain the net magnetization in the system due to 3d TM dopants in BCO system. • Ti doped BCO system found to be most stable due to lowest formation energy as compared to other 3d TM doped BCO system. In this paper, the influence of 3d transition metal (TM) dopants in BiCoO 3 (BCO) having C-type antiferromagnetism has been studied using first principles calculation. The value of c/a ratio is found to improve for Sc, V, Mn, Fe, Ni, Cu and Zn doping in BCO which indicates an increase in the tetragonality ratio upon introduction of these dopants in BCO. The formation energy calculations pointed out that it is easier to incorporate the TM atoms having number of d atoms lesser than that of Co (d < 7) in BCO. The electronic, and magnetic properties were studied and it was found that the electron/hole traps are introduced due to the presence of 3d TM dopant in BCO. The partial density of states reveal that V, Ni and Zn doped BCO exhibit half metallic characteristics with a lower band gap value among the other TM doped BCO systems. It was interesting to note that the presence of states in both spins at Fermi level due to Cu doping leads to a transition of BCO towards metallic behaviour in contrast to pure BCO having a clear band gap of 1.77 eV. The net magnetization was found to arise due to TM doping at Co site which may be attributed to the uncompensated Co spins and is mainly localized on the TM dopant. Successive spin polarization model (SSP model) was used to explain the net magnetization in the system due to 3d TM dopants in BCO system. The electron localization function plots also reveal that for d < 5 the electrons are localised near the TM metal ions and for d > 5 the localization impacts the near neighbouring Co ions. From this study, it is suggested that the magnetic and electronic properties of BCO system, can be tuned by 3d TM doping which has vast potential in photovoltaic and magneto-electric applications. [ABSTRACT FROM AUTHOR]

• The intrinsic room-temperature ferromagnetic behavior can be realized and regulated by external strain. • The structural deformation not only regulates the spin polarization feature but also leads to an electronic reconfiguration. • Our findings provide a new insight into designing 2D spintronic devices by strain engineering in hexagonal MIn 2 S 4 monolayers. The electronic occupation at 3d transition metal and crystal symmetry play a critical role in realizing spin polarization, but the weak spin exchange interaction makes it difficult to obtain room-temperature ferromagnetism, especially in two-dimensional (2D) materials. Different from traditional bulk phase with semiconducting feature, the free-standing hexagonal MIn 2 S 4 (M = Fe, Co, Ni, Mn) monolayers are proposed to discuss the strain-dependent magnetic behavior, in which the 3d-orbital hybridization and charge transfer can be regulated by structural deformation to enforce their spin exchange interaction, finally leading to a room-temperature 2D magnetic characteristic. The calculations disclose that the structural deformation not only regulates the spin polarization feature but also leads to an electronic reconfiguration. Our findings provide a new insight into designing 2D spintronic devices by strain engineering in hexagonal MIn 2 S 4 monolayers. [ABSTRACT FROM AUTHOR]

A new theoretical concept of an electrically controllable single-electron spin filter (polarizator) based on the exchange interaction in the system of interacting quantum dots or impurity atoms is proposed. The sign of the spin polarization of the current flowing through the device can be effectively controlled in two ways (i) by changing the applied bias and (ii) by tuning the tunnel coupling via an external gate. The minimal realization involves three bound state levels coupled to the contact leads. One of these levels is occupied by a single electron with a certain spin and the two-electron occupation is prohibited by a strong on-site Coulomb repulsion. Interestingly, while the spin polarization of this state is fixed, the sign of the single-electron current spin polarization flowing between the contacts through two consistent bound state levels can be switched. • A new theoretical concept of an electrically controllable single-electron spin filter is proposed. • The presence of both exchange interaction and on-site Coulomb repulsion is important. • Spin-filtering can be organized by changing the applied bias or by tuning the tunnel coupling via an external gate. • The considered phenomena are sensitive to electron correlations giving an experimental access to the many-body phenomena. • The obtained results open the possibility for precise control of tunneling current spin polarization. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic and magnetic properties of pristine and defected sheets before and after Sc metal decoration are investigated. • The E g values are reduced in the order of pristine(2.01 eV) > 55-77 (1.90 eV) > 5–8-5(1.90 eV) > 4-55-7777(0.58 eV). • The Sc-1 metal decoration produces one unpaired electron to the complex which transforms it to the magnetic state. • The highest spin polarization of P = 4.15 in Pristine_A and P = 3.41 in the 4-55-7777_I complex is obtained. To scrutinize the electronic and magnetic properties of fluorinated pristine, stone wales, di-vacancy, and two stone wales defected graphene sheets by scandium (Sc) metal decoration, the density functional theory is used. The obtained maximum binding and interaction energy values confirm that the two Sc metals decorated on the direct top and bottom of pentagonal rings of the two stone wales graphene sheet have stronger interactions than others. To validate the interactions, natural population analysis and electron density difference map are performed, revealing that Sc metal is the electron donor in all complexes. After the formation of defects in the pristine sheet, energy gap values are reduced in the defected sheets. The density of states infers the shift in the fermi level of all complexes after defect formation and metal decoration. The ultraviolet–visible spectral analysis exposes the highest absorption peaks of all bare sheets at the UV region and after Sc metal decoration, the peaks get red shifted. The results show that Sc metal decorated on two stone wales graphene sheet interacts better with Sc metals than other complexes. The decoration of single Sc metal in all four bare sheets transforms the sheet from a non-magnetic to a magnetic state but when two Sc metals are decorated it became non-magnetic. The highest degree of spin polarization, P = 4.15 is obtained while decorating a single Sc metal on the hexagonal ring of the pristine sheet. The outcome of this work suggests that Sc metal decoration on pristine and defected graphene sheets has great potential to improve the electronic and magnetic properties of graphene for designing spintronic and data storage devices. [ABSTRACT FROM AUTHOR]

• Optical conductivity in magnetic atoms embedded in honeycomb lattices is studied. • Anisotropic longitudinal and transverse currents, controlled by photon frequency, are predicted. • Magnetic phases play a crucial role in anisotropic transport. • Valley Hall current can be controlled. • Predicting optoelectronic devices with stable transmission, operating over a wide range of light frequencies. We investigate the optical properties of a hexagonal lattice with spin-spin interaction. Transition metal atoms with 3d-orbitals, for example Cr, Fe, Co, Ni, can be embedded in the lattice, exhibiting a strong magnetic moment. Spin polarization controls the magnetic phases, which can be ferromagnetic (FM), ferrimagnetic (FR), or antiferromagnetic (AFM). The behavior of electrons can resemble both massless and massive particles when varying the angle between spin-spin interactions. This leads to the investigation of the electronic properties of alternative materials, such as MXenes, for optoelectronic devices with stable transmission across a wide range of light frequencies from near-infrared to the ultraviolet regime. Furthermore, anisotropic optical conductivity and transmittance could be used to identify the spin orientation and atomic arrangement in magnetic materials. [ABSTRACT FROM AUTHOR]

Vanadium Nitride based magnetic heterostructures have opened up unprecedented opportunities in the field of spintronics owing to their half metallicity and a high value of spin polarization. In this paper, a tight-binding model of epitaxially grown VN/AlN/VN heterostructure is developed with different types of bonding at the left and right interface. The Slater–Koster tight-binding scheme is used to obtain the on-site and hopping energies of the model by fitting them to bulk DFT band structures. Electron transport across the VN/AlN/VN heterostructure is then studied using the non-equilibrium Green's function method, which works well within the tight-binding framework. An asymmetry in the interface bonding of the structure was found to produce a resonance peak in the transmission spectra at around 0.5 V. Beyond 0.5 V, the tunnel junction registers a large antiparallel current resulting in a negative tunnel magnetoresistance. Moreover, the presence of a magnetic impurity in the insulating barrier enhances tunneling across the junction resulting in a large current that decreases with the value of intra-atomic Coulomb repulsion, U , at the impurity site. • Half metallic Vanadium Nitride acts as a spin injector. • An asymmetric interface leads to a negative TMR. • Magnetic impurities in the barrier enhances the current. • Manipulation of spin valve current by impurity spin coupling. [ABSTRACT FROM AUTHOR]

• This article reviews recent work on chirality-induced spin selectivity (CISS), which has been extensively studied over the last two decades. • While current-induced spin polarization in chiral molecules is widely accepted as the fundamental principle of the CISS, only a few studies on bias-current-free CISS have been reported. • The possible mechanism of bias-current-free CISS, i.e. thermally driven broken-time-reversal symmetry of chiral molecules at the interface is discussed. Chirality-induced spin selectivity (CISS) has been extensively studied over the past two decades. While current-induced spin polarization in chiral molecules is widely recognized as the fundamental principle of the CISS, only a few studies have been reported on bias-current-free CISS, where there is no bias electric current in chiral molecules. Recent studies on the chirality-induced exchange bias and current-in-plane magnetoresistance (CIP-MR) effects using chiral molecule/ferromagnet bilayer systems indicate that chiral molecules at the interface possess thermally driven broken-time-reversal symmetry, which induces bias-current-free CISS, i.e. a spontaneous effective magnetic field in the system. In this paper, we briefly review CISS-related phenomena in terms of the symmetry and discuss the mechanism of bias-current-free CISS. We also discuss the possibility of the linear magnetoelectric effect of chiral molecules, which arises from the spin polarization at the edges of molecules with metallic contacts, and its potential impact on the observed CISS phenomena. [ABSTRACT FROM AUTHOR]

• We performed a computational and theoretical study of FeCrTiAl. • Our calculations indicate that this material undergoes several band structure transitions. • Another interesting feature of FeCrTiAl is that its spin polarization changes sign from negative to positive under pressure. • At the largest considered lattice parameters, this compound exhibits nearly 100% spin polarization. Spin-gapless semiconductors (SGS) represent a new type of compounds with potential applications in novel spintronic devices. Here, we performed a comprehensive computational and theoretical study of FeCrTiAl, a quaternary Heusler compound that was recently predicted to exhibit nearly SGS properties. Our calculations indicate that this material undergoes several band structure transitions from essentially semimetallic phase at smaller lattice constants to nearly type-II SGS at the ground state, then to nearly type-III SGS and further to nearly type-I SGS, as the lattice parameter is increased. Another interesting feature of FeCrTiAl is that its spin polarization changes sign from negative to positive as the volume of the cell increases. At the largest considered lattice parameters, this compound exhibits nearly 100% spin polarization. The mechanical expansion discussed in this text may be achieved, in principle, either by applying an epitaxial strain in thin-film geometry, or by chemical substitution, for example with non-magnetic element of larger atomic radius. We hope that the presented results may provide guidance for further research on mechanical strain induced manipulation of electronic and magnetic properties of spin-gapless semiconductors. [ABSTRACT FROM AUTHOR]

• Our paper introduces a spin transport model based on the drift-diffusion equation for non-collinear magnetic configurations taking account of diffuse interfaces. • The spin dephasing term is required to introduce into the spin transport model since it is responsible for the enhancement of spin-transfer torque and magnetoresistance (MR). We propose a theoretical model to study the spin transport, particularly the interfacial resistance in a noncollinear system with a diffuse interface. The realistic interface region arising from the sputtering process is first modeled by using Fick's law. Subsequently, the spin transport behavior in magnetic system is determined via a generalized spin accumulation model taking into account spin dephasing term. Our model is able to deal with magnetic systems with arbitrary orientation of magnetization by employing the transfer matrix approach. The model is first used to investigate spin accumulation in a bilayer system consisting of a ferromagnet (FM) and a non-magnet (NM). The influence of important transport parameters: spin dephasing, interdiffusion, injected current density and spin polarization on magnetoresistance (MR) are studied. Next we investigate the transport properties of a FM/NM/FM system where the interface disorder giving rise to enhanced spin dephasing is modeled. We found that the interdiffusion of the FM/NM/FM interface gives rise to large spin scattering, which enhances the GMR. The results also show that including the disorder arising from interface diffusion is an important contribution to the transport properties. [ABSTRACT FROM AUTHOR]

• Origin of the large saturate moment at 5 K in Fe 2 MnGe DO 19 phase was determined. • Phase stability of cubic and hexagonal Fe 2 MnGe was investigated. • "Why Fe 2 MnGe DO 19 phase is stable at room temperature" was discussed. • Information on electronic structure of Fe 2 MnGe DO 19 phase was presented. The electronic structure, phase stability and magnetic properties of cubic and hexagonal type Fe 2 MnGe were investigated and compared with the well-known Heusler alloy Fe 2 MnSi. Three different structures L2 1 , DO 3 and DO 19 were considered for them. In both alloys the cubic phase (L2 1 and DO 3) has a lower total energy comparing with the hexagonal DO 19 phase at 0 K. But in Fe 2 MnGe the energy difference between the DO 19 and L2 1 phases is much smaller than Fe 2 MnSi. The DO 3 disorder can lower the stability of the cubic phase further and make the total energies of hexagonal and cubic phases closer, this can help the DO 19 phase gain stability. Finally, in Fe 2 MnGe, the energy difference is 0.12 eV/f.u., much smaller than the 0.41 eV/f.u. in Fe 2 MnSi. That is the possible reason why Fe 2 MnGe DO 19 phase can be synthesized experimentally and Fe 2 MnSi cannot. L2 1 type Fe 2 MnGe is a half-metal with 100% spin polarization and has a total spin moment of 3μ B /f.u. The spin polarization ratio of DO 3 phase is also high. But for the DO 19 hexagonal phase, a normal ferromagnetic metal character is observed. The calculated total moment for DO 19 type Fe 2 MnGe is larger than 6μ B /f.u. This total moment comes mainly from the large and parallel coupled partial spin moments of Fe and Mn. [ABSTRACT FROM AUTHOR]

Highlights • We studied the structural, electronic and magnetic properties of transition-metal (TM) (Cr, Mn, Fe, Co, Ni and Cu) adatoms on WS 2 monolayer by performing first-principles calculations. • Based on the adsorption energy, TM atoms prefer to occupy the T W site, above the W atoms, for all the cases. • The results indicate that systems of Cr, Mn, Fe and Co adsorbed on WS 2 monolayer are magnetic, while in Ni and Cu atoms adsorbed don't have any magnetic properties. • The TM atoms are adsorbed chemically to the WS 2 layer. The obtained values of the total magnetic moment vary from 4 μ B to 1 μ B in case of Cr to Co adsorption, respectively, which agree with the Slater-Pauling rule. • Based on magnetic moment of 0.00 μ B , non-magnetic states are realized for Ni and Cu adsorption. More importantly, a high spin polarization of 100% at the Fermi level is achieved in the Cr, Mn, Fe and Co adsorption, which implies the potential for application in spintronic devices. Abstract Given the various applications of half-metals in the spintronics devises, we studied the structural, electronic and magnetic properties of transition-metal (TM) (Cr, Mn, Fe, Co, Ni, and Cu) adatoms on WS 2 monolayer by performing first-principles calculations. Based on the adsorption energy, TM atoms prefer to occupy the T W site, above the W atoms, for all the cases. The results indicate that systems of Cr, Mn, Fe, and Co adsorbed on WS 2 monolayer are magnetic, while in Ni and Cu atoms adsorbed don't have any magnetic properties. The TM atoms are adsorbed chemically to the WS 2 layer. The obtained values of the total magnetic moment vary from 4 μ B to 1 μ B in case of Cr to Co adsorption, respectively, which agree with the Slater-Pauling rule. Based on the magnetic moment of 0.00 μ B , non-magnetic states are realized for Ni and Cu adsorption. More importantly, the high spin polarization of 100% at the Fermi level is achieved in the Cr, Mn, Fe and Co adsorption, which implies the potential for application in spintronic devices. [ABSTRACT FROM AUTHOR]

Highlights • The spin polarization of hybrid interface states is manipulated by selecting anchoring groups with different types of outer orbitals and atomic electronegativity. • A dependence of the interfacial spin polarization on the atomic electronegativity is revealed. • Significant enhancements of the tunneling magnetoresistance and spin filtering efficiency are realized by using the anchoring atoms with large electronegativity. Abstract Based on density functional theory combined with nonequilibrium Green's function method, the spin polarization of hybrid interface states in magnetic molecular junctions and their roles in spin-dependent transport are investigated. The results demonstrate that by choosing anchoring atoms with different types of outer orbitals, the spin polarization of the hybrid interface states can be tuned. A dependence of the spin polarization on the atomic electronegativity is revealed, where a high spin polarization is achieved in the case of O atom with large electronegativity. The transport calculation shows that a corresponding adjustable spin-dependent transport is realized, where an enhanced tunneling magnetoresistance and a large spin filtering efficiency are realized by using the anchoring atoms with large electronegativity. This work proposes a valid way to enhance the functionality of molecular spintronic devices by manipulating the hybrid interface states. [ABSTRACT FROM AUTHOR]

Highlights • Highly (0 0 l)-oriented heterostructures of BZT-BCT/LSMO on LAO. • The well-behaved M-H hysteresis loops for the heterostructure. • Magnetoelectric coupling between BZT-BCT and LSMO layers. • Very low Gilbert damping parameter due to spin orbit coupling. Abstract In this article, dynamic magnetic properties of La 0.7 Sr 0.3 MnO 3 (LSMO) thin film capped with a Pb-free ferroelectric BZT-BCT layer deposited on two different substrates, i.e. lanthanum aluminate (LAO) and Platinum (Pt), by pulsed laser deposition (PLD) have been investigated using ferromagnetic resonance (FMR) spectroscopy. The heterostructures of BZT-BCT/LSMO on LAO substrate were highly (0 0 l)-oriented whereas these were randomly oriented on Pt substrate. The well-behaved M-H hysteresis loops were observed at room temperature for both heterostructures indicating the ferromagnetic behavior of LSMO. The right shift of the hysteresis loop of the heterostructure was observed due to the magnetoelectric coupling between ferroelectric and ferromagnetic layers. The FMR measurements yield optimum values of different important parameters such as the linewidth offset, Gilbert damping, gyromagnetic ratio, and in-plane uniaxial anisotropy field of the thin films, which are essential to design spin valve and magnetic tunneling based devices. We found the lowest Gilbert damping parameter of ∼0.03 for the BZT-BCT/LSMO/LAO heterostructure due to spin orbit coupling. In addition, the gyromagnetic ratio was also obtained to be small (0.002 GHz/Oe) in the same film. These results open new possibilities to use BZT-BCT/LSMO heterostructure for future spintronic device applications. [ABSTRACT FROM AUTHOR]

Highlights • The change of sign of anomalous of permalloy film was observed. • The modulation of anomalous Hall effect by oxide in permalloy was found. • The spin accumulation induced by AHE was explored in a multilayer structure. Abstract We report that the unusual behavior of anomalous Hall effect (AHE) in permalloy (Fe 20 Ni 80 , Py) thin film with silicon oxide (SiO 2) as an adjacent layer. It is found that sign of AHE changes from positive to negative with decrement in thickness of Py. Through the AHE measurement, we demonstrate that this unusual behavior originates from the interface of Py/SiO 2 rather from the structural inversion asymmetry. In the Pt/YIG/Cu/Py/SiO 2 multilayer structure with a charge current injected in the Py layer, the information on spin accumulation at the YIG/Cu interface induced by the AHE in Py, can be obtained from the nonlocal voltage measured in the Pt layer. Through the nonlocal measurement, it is found, however, the electrons with same spin for interfacial Py near the SiO 2 layer and bulk Py are scattered to the same direction. Hence we can deduce that the sign of spin polarization of the conductivity closely related to the asymmetry in density of states at the Fermi level for interfacial Py and bulk Py should be opposite to each other, which is responsible for the abnormal AHE observed. Our results demonstrate that oxide layer can drive the change of sign of AHE of Py, which provide an alternative way of manipulating the spin-related transport. [ABSTRACT FROM AUTHOR]

Highlights • Detection of voltage due to spin accumulation induced by anomalous Hall effect. • Observation of field-dependent spin accumulation induced by anomalous Hall effect. • Demonstration of dependence of anomalous Hall voltage on spin polarization of conductivity. Abstract We present an experimental observation of interfacial spin accumulation induced by anomalous Hall effect (AHE) in ferromagnets (FMs) in a multilayer structure of FM/YIG/Pt, where the direction of charge current injection in FM layer is perpendicular to the direction of voltage detection in Pt layer. In this structure, the magnon-mediated drag voltage (V drag) due to the interfacial spin accumulation induced by AHE, can be unambiguously separated from spin Seebeck voltage (V SSE) by sweeping or rotating the applied magnetic field. Field-dependent spin accumulation induced by AHE has been observed by comparison of nonlocal voltages between Ni/Cu/YIG/Pt and Pt/YIG/Pt samples. Furthermore, we demonstrate that the AHE voltage strongly depends on the spin polarization of conductivity and spin Hall angles of electrons with opposite spins in FMs. Our results show a prospect for FMs to be field-control spin generators via AHE, and provide a new viewpoint to realize the AHE. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Introducing a new type of spin-torque-oscillator (STO), all-in-plane STO for MAMR. • All-in-plane STO consisting of Spin-Injection-Layer and Field-Generating-Layer. • Large oscillation cone angle of FGL after magnetization switching of SIL. • Design of SIL for oscillation of FGL at a frequency above 20 GHz. Abstract A new type of spin-torque-oscillator (STO), all-in-plane STO, is introduced for microwave assisted magnetic recording (MAMR) that consist of a spin-injection-layer (SIL) and a field-generating-layer (FGL) with an effective in-plane easy axis due to the shape anisotropy separated with a metallic spacer. In this device, electrons are injected from SIL to FGL while the magnetization of the SIL and FGL is saturated to the out-of-plane by the external magnetic field of ∼1.0 T. Micromagnetic simulations showed that the magnetization direction of SIL can be switched to the opposite direction to that of the applied external magnetic field by the use of spin-transfer-torque. This results in a larger spin accumulation in FGL and its oscillation with a large cone angle at a low bias current density. We designed SIL to reduce the critical current density, J c , required for the magnetization switching of SIL. Materials with a smaller saturation magnetization in SIL reduce J c. Smaller spin polarization of SIL leads to a larger spin accumulation in SIL with an opposite direction to the magnetization, resulting in a reduction of J c. This enables magnetization switching of SIL in small J c followed by oscillation of FGL with frequency above 20 GHz with a large out-of-plane oscillation cone angle of 45–50°. The validity of this finding was studied experimentally by developing STO with two SIL materials, Co 2 Fe(Al 0.5 Si 0.5) Heusler alloy and Fe 67 Co 33 , the former has the B2 crystal structure with a large spin polarization and the latter has the A2 crystal structure with a smaller spin polarization. The magnetization configuration of SIL and FGL in STO with a diameter of ∼60 nm is investigated experimentally based on the field dependent resistance change and the oscillation behavior is discussed based on the micromagnetic simulations. [ABSTRACT FROM AUTHOR]

Highlights • Magnetic and electronic properties of Cd 1-x Zn x Cr 2 Se 4 have been studied experimentally and theoretically. • The difference in energy between the antiferromagnetic (AFM) and ferromagnetic (FM) states reveals the magnetic competition coexisting in this system. • All samples were found to keep 100% spin polarization and behave as half-metallics. Abstract We have studied the magnetism of crystalline Cd 1-x Zn x Cr 2 Se 4 spinels with (0.35 ≤ x ≤ 0.55) under magnetic field up to 15 T. The total magnetic moment, Curie temperature, lattice parameter and exchange integrals were found to decrease with Zn substitution. Ab -initio calculations carried out using full potential augmented plane wave (FP-LAPW) method were performed to study the magnetic, and electronic structure using generalized gradient approximation (GGA) and the modified Becke-Johnson (mBJ) to correct the gap's energy. The obtained results were in good agreement with the experimental ones. It is shown that there is a competition between ferromagnetic (FM) and antiferromagnetic (AFM) interactions: the super-exchange mechanism slightly increases the AFM contribution and keeps the FM the dominant mechanism in this range of substitution. From the density of states, we demonstrate that the system keeps the half-metallic state for the composition range 0.125 ≤ x ≤ 0.55 with 100% spin polarization. Our results highlight that it is possible to obtain a half-metallic semiconductor with tunable magnetic state which is promising for applications in spintronics. [ABSTRACT FROM AUTHOR]

Highlights • Interface termination of FeRh films on MgO has a tremendous effect on the magnetic-phase order and magnetic anisotropy. • The presence of Rh layer at the interface next to MgO as well as vacuum leads to a very robust interfacial ferromagnetism and large magnetic anisotropy of about 2 meV, which is an order of magnitude greater than those for the Fe-terminated FeRh/MgO. • This large anisotropy is attributed to the interplay of the spin-polarized Rh d xy and d x 2 - y 2 orbital states with large spin-orbit coupling at the interface. Abstract Employing first-principles calculations we reveal the strong interface termination dependences of the magnetic order and perpendicular magnetic anisotropy (PMA) in FeRh films on MgO(0 0 1). While the magnetic ground state of the Fe-terminated FeRh(0 0 1) is an antiferromagnetic, the Rh-termination favors ferromagnetism within the underlying FeRh layers. This ferromagnetism can persist even at the interface with MgO, which in turn leads to a few times enhancement of PMA compared with the Fe-interface in FeRh/MgO(0 0 1). The underlying mechanism for this large PMA is an interplay between the spin-polarized Rh d xy and d x 2 - y 2 orbital states with large spin-orbit coupling at the interface. These results unveil a crucial role of the interface termination on magnetism of FeRh in antiferromagnet spintronics. [ABSTRACT FROM AUTHOR]

Abstract Magnetization switching by injected spin-polarized current or applied field pulses is considered for perpendicular magnetic nanosystems with uniaxial symmetry and subject to thermal fluctuations. Such systems can model both perpendicular spin-transfer-torque magnetic random access memories and magnetic grains for state-of-the-art perpendicular recording. It is shown that, in the limit of high energy barriers and large current/field amplitudes, the probability and cumulative distribution functions of switching times can be analytically computed as function of material, geometrical parameters and thermal noise level. The theoretical predictions are confirmed by macrospin and full micromagnetic simulations. By using the derived formulas, it is shown that analysis of Write-Error Rates (WERs) at typical levels of reliability required by magnetic recording technology can be easily performed. [ABSTRACT FROM AUTHOR]

Highlights • The spin filtering ability of lead/poly-BIPO/lead model junction is investigated. • We use a modified SSH model Hamiltonian and Landauer – Büttiker formalism. • We found that in the presence of polarons the completely spin-polarized is possible. Abstract The spin filtering ability of lead/poly-BIPO/lead model junction is investigated. A polaron excitation is considered at the center of polymer. Four polaron types are assumed as the spin and charge density distributions. The Su-Schrieffer-Heeger (SSH) Hamiltonian is modified by Hubbard and Heisenberg Hamiltonians to include the spin and charge interactions. The spin-oriented currents and spin-polarization ability of the model, in the presence/absence of polaron excitations are examined. We find that the complete spin-polarization for both of the excited and non-excited systems is possible and for a given voltage range it is a 100% plato. Our results predict that in the presence of polaron excitations the spin-oriented current is enhanced. [ABSTRACT FROM AUTHOR]

Highlights • Finite-temperature electron transport is studied by ab initio alloy analogy model. • Phonons, magnons and chemical disorder are treated in a unified way. • Calculations reproduce successfully the measured electrical resistivity. • At temperature 600 K, spin polarization of the current as high as 80% is predicted. • At the Curie temperature 730 K, the Matthiessen's rule is violated by 16%. Abstract We investigate theoretically the combined effect of phonons and magnons caused by finite temperatures on the electrical resistivity of nonstoichiometric half-Heusler NiMnSb alloy. The coherent potential approximation within the alloy analogy model is employed for an efficient treatment of chemical impurities, atomic displacements, and magnetic disorder. Spin fluctuations of local Mn moments are described by two models: (i) uncompensated disordered local moment approach and (ii) tilting of the moments. The calculated resistivity agrees with experimental data, the agreement is good up to 600 K. We show that a strong magnetic disorder leads to a violation of the Matthiessen's rule for the resistivity. We also discuss the spin polarization of the electrical current which exceeds 90% at room temperature but it is dramatically reduced by the magnetic disorder for higher temperatures approaching the Curie point ( T C = 730 K). [ABSTRACT FROM AUTHOR]

Highlights • By increasing the current, three motion regimes of the bound vortices were observed. • The frequency dependence of the stationary oscillations of vortices is linear. • By current, you can switch the polarity of the vortex only in a thick magnetic layer. • When the polarity of the vortex is switched, a vortex antivortex pair is formed. Abstract We study dynamics of two magnetostatically coupled magnetic vortices excited by spin-polarized electrical current in a nanopillar consisting of permalloy magnetic layers with different thickness separated by a nonmagnetic spacer. We demonstrate three dynamical regimes of the vortices bound motion: damped oscillations, stationary oscillations and a regime of the polarity switching of one of the vortices; the critical currents for each dynamical phase are identified. The structure and trajectory of the vortex core motion in each magnetic layer are studied for the case of the vortex polarity switching in a thick layer. We show that the vortex polarity switching process has a dynamic nature and is associated with a vortex-antivortex pair formation. [ABSTRACT FROM AUTHOR]

Highlights • Novel spin cycloids whose plane do not contain polarization are found in BiFeO3. • In contrast to the bulk two cycloids q || [0 0 1] , [ 1 1 ¯ 0 ] can be realized in BiFeO3 film. • Phase transitions between cycloids in (1 1 0) BiFeO3 film are explored. Abstract We report on the novel cycloids that can be realized in epitaxial BiFeO 3 films. We found two featured (1 1 0) and (1 1 ¯ 0) plane cycloids in the (1 1 0) oriented BiFeO 3 film and considered the action of compressive and tensile deformations on the areas of the cycloids stability. Our findings show that additional magnetic anisotropy induced by the strains allocates cycloids with the definite directions of spin rotation and electric polarization and change the properties of space modulated structures. Until now, it was believed that polarization is linked with antiferromagnetic order throughout the plane of spin rotation, namely it was considered that polarization always lies in the cycloid spin rotation plane. We show that due to the action of epitaxial strains spin rotational plane of the cycloid deviates from the plane containing intrinsic spontaneous polarization P s. [ABSTRACT FROM AUTHOR]

Highlights • Magnetic resonance in combination with optics is the basis of Mx magnetometers. • Magnetometers sensitivity is improved by harmonic detection of magnetic resonance. • The dependencies of the harmonic number with the best sensitivity is investigated. • Relaxation time of spin polarization can affect the selection of best harmonics. Abstract Measurement of extremely weak magnetic fields in double-resonance atomic magnetometers based on resonant optical excitation has been an active area of research in recent years. Magnetometer sensitivity can be improved via detection of higher harmonics of the magnetic resonance, a resonance which has a maximum sensitivity under conditions where the ratio of the amplitude to the line-width of the resonance signal is maximized. Based on the Bloch theorem, we analyze the time evolution of the spin polarization corresponding to each harmonic component of the resonance signal and measure this progression experimentally. Our results revealed that there is an optimal harmonic number for achieving the highest sensitivity. We have shown that the longitudinal and transverse relaxation times of spin polarization can manipulate the harmonics with the best sensitivity while the excitation frequency is detuned from the Larmor frequency. [ABSTRACT FROM AUTHOR]

Highlights • Onset of magnetization on nitrogen in two dimensional carbon based structures. • Increase of magnetization with extension of carbon network C x N (x = 2, 6, 12). • Proposed C 6 N and C 12 N are found ferromagnetic in the ground state. • Strongly ferromagnetic behavior with full magnetic polarization of N-p electrons. Abstract Identification of unusual onset of spin polarization of N(p) states is reported. Full saturation up to 3μ B (Bohr Magnetons) is demonstrated within extended two-dimensional carbon networks of C x N (x = 2, 6, 12) hexagonal structures refined based on density functional theory calculations. The cohesive energy is found to increase along the extension of the carbon network which opens perspective to experimental investigations through reactive deposition of thin films. From establishing the energy-volume equations of states of the two carbon rich nitrides done with assuming spin degenerate (non spin polarized) and spin-polarized configurations, the ground state is identified as ferromagnetic in both C 6 N and C 12 N. The electronic density of states plots show vanishing intensities at the Fermi level, whence the integer magnetizations. The variation of magnetization with volume points to strongly ferromagnetic behavior. [ABSTRACT FROM AUTHOR]

The thermoelectric properties (TE) of rare-earth based RENi 2 (RE = Dy, Ho and Er) Laves phase compounds, have been investigated using first-principle density functional theory. The generalized gradient approximation (GGA) and local spin density approximation (LSDA) with Hubbard parameter (U) have been used for exchange and correlation effect. Calculated ground state properties such as lattice constants are in good agreement with pervious reported results. The electronic band structures display the metallic nature of these compounds. The high values of N(E F ) are responsible for more metallic nature in spin down channel as compared to spin up channel. The electrical conductivity (σ/τ) decreases with increasing temperature. The negative value of Seebeck coefficient indicates that electrons play major role in spin up profiles but in spin down profiles both type of charge carriers are contribute for Seebeck effect. [ABSTRACT FROM AUTHOR]

Highlights • Spin-polarized transport through topologically superconducting wire is studied. • Current-switch effect mediated by Majorana bound states (MBSs) is found. • The effect is based on the dependence of MBS spin polarization on magnetic-field orientation. • The direction of spin-polarized current can be changed by magnetic gate. • The observed current-switch effect allows electrical detection of the MBSs. Abstract We present the study of transport properties of a superconducting wire with strong Rashba spin-orbit coupling for different orientations of an external magnetic field. Using the nonequilibrium Green’s functions in the tight-binding approach the crucial impact of the relative alignment of lead magnetization and the Majorana bound state (MBS) spin polarization on the low-bias conductance and shot noise is presented. Depending on this factor the transport regime can effectively vary from symmetric to extremely asymmetric. In the last situation the suppression of MBS-assisted conductance results in current-switch effect allowing the electrical detection of the Majorana fermions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The full Heusler alloy (Fe 2 CoSn) nanowires are formed using AC electrodeposition in AAO templates. • The SEM images have confirmed the average diameter and length of nanowires 40–60 nm and 15 μm respectively. • The M-H loops show the variation of coercivity and saturation magnetization with respect to deposition potential. • The half-metallicity, band gap and 100% spin polarization was also confirmed using density functional theory (DFT). Abstract Fe 2 CoSn Heusler alloy nanowires (NWs) were synthesized for the first time through alternating current (A.C) electrodeposition due to its manufacturing and size tailoring ease. To approach our desired goal, deposition potential was used to control the alloy composition of Fe, Co and Sn contents as it was almost inversely proportional to the composition ratio of Sn and (Fe, Co). The effects of deposition potential on morphology, chemical composition, crystal structure and electric/magnetic properties were investigated. According to the scanning electron microscopy (SEM) micrographs, the Fe 2 CoSn NWs exhibited diameter of about 40–60 nm range and the length existing in the range of 15 µm. X-ray diffraction (XRD) patterns reveal that two types of reflection were observed i.e. fundamental (A2-type crystal structure) and super-lattice (L2 1 crystal structure) reflection. Almost 35 nm was the average grain size calculated through XRD technique using full width half maximum (FWHM). The composition of Fe 2 CoSn nanowires has been confirmed by using EDX analysis, whereas surface chemistry of Heusler alloy (Fe 2 CoSn) NWs was examined through FTIR. Magnetic measurement indicated that Fe 2 CoSn Heusler alloy was ferromagnetic at room temperature with a maximum coercivity of 484 Oe at 17 V. Two probe (I-V) curve showed non-ohmic character and Hall measurement (Four probe) revealed the inverse relation between resistivity (ρ), mobility (µ) and followed excellent transport as well as spin dependent properties of Heusler alloy (Fe 2 CoSn) NWs. Half metallicity in (Fe 2 CoSn) Heusler alloy NWs was confirmed by full potential lineralized augmented plane wave methods (FP-LAPW) within density functional theory (DFT) in detail. These results revealed that Heusler alloy (Fe 2 CoSn) NWs have wide range of multifunctional properties such as combination of magnetism and exceptional transport properties in spintronic devices. [ABSTRACT FROM AUTHOR]

Highlights • Surface antiferromagnetism of the Cr(0 0 1) c(2 × 2) surface. • Quantitative determination of the antiferromagnetic coupling angles. • New spin quantization axes along the [1 1 0] of Cr(0 0 1). Abstract We present spin-polarized scanning tunneling microscopy results for 8 micrometer thick, chromium (0 0 1)-oriented thin films deposited using molecular beam epitaxy on MgO(0 0 1) substrates, achieving a smooth, atomically-stepped staircase morphology. The c(2 × 2) surface structure of the Cr(0 0 1) surface was found via atomically-resolved scanning tunneling microscopy images and dI/dV spectroscopy. A practical method of interpreting spin-polarized scanning tunneling microscopy dI/dV images was developed and applied to the c(2 × 2) Cr(0 0 1) surface structure. A 180° spin reversal between atomic layers, characteristic of a topological, layer-wise antiferromagnetic spin structure, was quantitatively verified. In addition, the spin anisotropy directions for 3 different antiferromagnetic, atomic staircase domains occurring on the c(2 × 2) surface were quantitatively determined to coincide with the [1 0 0], [0 1 0], and [1 1 0] crystallographic axes of chromium. [ABSTRACT FROM AUTHOR]

Highlights • A spin current generator in a single molecular magnet is realized. • The spin-related currents are studied by Hubbard operator Green’s function method. • The system can generate spin-polarized current or pure spin current. • Two configurations of spin bias are considered and they show different features. Abstract In this paper we study the spin- and charge-transport behaviors of a single molecular magnet (SMM) coupled to external reservoirs with spin-dependent chemical potentials. By using the Hubbard operator Green’s function method, we show that in the limit of a pinned macrospin the SMM can serve as an effective spin current filter or generator. Two configurations of spin bias are considered. For SMM coupled with symmetric dipolar spin bias, the system can generate spin-polarized current and pure spin current by adjusting the relative magnitude of spin bias and Coulomb interaction. It originates from the competition of two spin-opposite transport channels. Also due to this competition, one can observe a negative differential spin conductance. For SMM coupled with asymmetric dipolar spin bias, the system can only generate spin-polarized currents. The SMM as a spin current generator shows features different from the usual quantum dot system and these features can be useful in molecular spintronics. [ABSTRACT FROM AUTHOR]