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We performed spin-torque ferromagnetic resonance studies on the Al/NiFe/AlOx heterostructure. We observed a large non-trivial field-like torque, τ FL z , due to the out-of-plane spin polarization, despite the lack of heavy metal in our multilayer. The torque conductivity is found to be significant with a value equal to σ FL z = (21 ± 2) ℏ 2 e × 10 3 Ω − 1 m − 1 . From a detailed Al thickness dependence, we show that τ FL z arises from the interface between Al and NiFe. We demonstrate that the observed τ FL z arises from the spin-swapping mechanism at the Al/NiFe interface rather than the orbital Hall effect of Al. This observation of a non-trivial spin–orbit torque in the low-cost light element, Al, is highly significant for the energy-efficient control of spintronic devices. [ABSTRACT FROM AUTHOR]

Constructing a mixed-dimensional (MD) graphene-based van der Waals heterostructure (vdWH) is a viable technique for opening the bandgap and introducing spin polarization in graphene. In this work, we discovered that the adjacent MnF4 can manipulate the carrier doping, bandgap opening, and spin polarization of graphene in the MD vdWH of graphene/MnF4 comprised of two-dimensional (2D) graphene and one-dimensional atomic wire (1D AW) MnF4. By adopting first-principles calculations, we found that graphene can achieve effective p-type doping with the carrier density up to ∼8.89 × 1013–1.03 × 1014 cm−2. With a twisted angle of θ = 10.89° and the compressed distance of dMn-Gra = 2.84 Å, the opened bandgap of graphene (Eg-Gra) achieves 35 and 57 meV for spin-up and spin-down channels due to the sublattice symmetry-breaking in graphene, and the spin splitting energy (ΔES) at the Dirac point reaches 78.7 meV as a result of the graphene–MnF4 interlayer interaction. Remarkably, Eg-Gra is increased to 64 and 79 meV for spin-up and spin-down channels, and ΔES with 202.7 meV is obtained at dMn-Gra = 2.84 Å when the width of 1D MnF4 is doubled. Meanwhile, the n-type Ohmic contact is also realized. Our work underscores the rich interplay in the graphene/MnF4 MD vdWH and provides a significant route with fundamental insights to engineer the spintronic band properties of graphene. [ABSTRACT FROM AUTHOR]

Constructing a mixed-dimensional (MD) graphene-based van der Waals heterostructure (vdWH) is a viable technique for opening the bandgap and introducing spin polarization in graphene. In this work, we discovered that the adjacent MnF4 can manipulate the carrier doping, bandgap opening, and spin polarization of graphene in the MD vdWH of graphene/MnF4 comprised of two-dimensional (2D) graphene and one-dimensional atomic wire (1D AW) MnF4. By adopting first-principles calculations, we found that graphene can achieve effective p-type doping with the carrier density up to ∼8.89 × 1013–1.03 × 1014 cm−2. With a twisted angle of θ = 10.89° and the compressed distance of dMn-Gra = 2.84 Å, the opened bandgap of graphene (Eg-Gra) achieves 35 and 57 meV for spin-up and spin-down channels due to the sublattice symmetry-breaking in graphene, and the spin splitting energy (ΔES) at the Dirac point reaches 78.7 meV as a result of the graphene–MnF4 interlayer interaction. Remarkably, Eg-Gra is increased to 64 and 79 meV for spin-up and spin-down channels, and ΔES with 202.7 meV is obtained at dMn-Gra = 2.84 Å when the width of 1D MnF4 is doubled. Meanwhile, the n-type Ohmic contact is also realized. Our work underscores the rich interplay in the graphene/MnF4 MD vdWH and provides a significant route with fundamental insights to engineer the spintronic band properties of graphene. [ABSTRACT FROM AUTHOR]

Colloidal semiconductor nanoplatelets (NPLs) have emerged as low‐cost and free‐standing alternates of traditional quantum wells. The giant heavy‐ and light‐hole splitting in NPLs allows for efficient optical spin injection. However, the electron spin lifetimes for prototypical CdSe NPLs are within a few picoseconds, likely limited by strong electron‐hole exchange in these quantum‐ and dielectric‐confined materials. Here how this hurdle can be overcome with engineered NPL‐heterostructures is demonstrated. By constructing type‐I CdSe/ZnS core/shell NPLs, dielectric screening inside the core is strongly enhanced, prolonging the electron spin polarization time (τesp) to over 30 ps (or 60 ps electron spin‐flip time). Alternatively, by growing type‐II CdSe/CdTe core/crown NPLs to spatially separate electron and hole wavefunctions, the electron‐hole exchange is strongly suppressed, resulting in τesp as long as 300 ps at room temperature. This study not only exemplifies how the well‐established synthetic chemistry of colloidal heterostructures can aid in spin dynamics control but also establishes the feasibility of room‐temperature coherent spin manipulation in colloidal NPLs. [ABSTRACT FROM AUTHOR]

A spintronic terahertz (THz) emitter based on rare-earth-transition-metal ferrimagnetic alloys has drawn wide attention due to its prominent THz emission signals at a magnetic compensated state. Here, THz emission spectroscopy is performed in a layered ferrimagnetic/nonmagnetic structure of Ta/Tbx(FeCo)1–x/Pt to investigate the impact of magnetization and spin polarization on THz radiation. Composition and temperature-dependent THz emission signals are observed by an inverse spin Hall effect. The variation of THz amplitude approximately follows the in-plane magnetization in the composition range, yet a nonvanishing THz radiation at the compensation point indicates that net spin polarization dominates the emitted THz electric field rather than net magnetization in this two-sublattice system. A significant gap of 90 K between the compensation point of magnetic moment and spin polarization is found in a Tb0.24(FeCo)0.76 sample, which is a striking difference to that of 25 K in GdCo/Pt THz emitters. We attribute this anomalous gap to the strong intersublattice 3d-5d6s-4f exchange interaction of TbFeCo alloy; thus, the contribution of spin polarized Tb 4f electrons should be reconsidered after fs laser pulse excitation. These results gain insight into spin dynamics of complex multisublattice systems and pave the way for further optimized spintronic THz emitters to modulate THz radiation efficiently. [ABSTRACT FROM AUTHOR]

The electron tunneling in ZnO/ZnCdO semiconductor heterostructure is studied using the matrix method. The spin-polarization is examined due to Dresselhaus spin–orbit interaction and Rashba spin–orbit interaction. The total spin-polarization is mainly due to Dresselhaus spin–orbit interaction and the Rashba spin–orbit interaction is small. The high degree of spin polarization can be achieved at a high barrier width. With the increasing cadmium concentration in this heterostructure, the spin polarization efficiency is enhanced. The dwell time is reported and discussed. [ABSTRACT FROM AUTHOR]

The low separation efficiency of the photogenerated carrier and the poor activity of the surface redox reaction are the main barrier to further improvement of photocatalytic materials. To address these issues, introducing spin‐polarized electrons in single‐component photocatalytic materials emerged as a promising approach. However, the decreased redox ability of photocarriers in these materials becomes a new challenge. Herein, we mitigate this challenge with a carbon nitride sheet (CNs)/graphene nanoribbon (GNR) composite material that has a van der Waals heterostructures (vdWHs) and spin‐polarized electron properties. Experimental results and theoretical calculations show that the heterostructure has a strong redox ability, high carrier‐separation efficiency, and enhanced surface catalytic reaction. Consequently, the mixed‐dimensional CNs/GNR vdWHs exhibit remarkable performance for H2 and O2 generation as well as CO2 production under visible‐light irradiation without any cocatalyst. The spin‐polarized vdWHs discovered in this study revealed a new type of photocatalytic materials and advanced the development of spintronics and photocatalysis. [ABSTRACT FROM AUTHOR]

Multi-directional spin-to-charge conversion—in which spin polarizations with different orientations can be converted into a charge current in the same direction—has been demonstrated in low-symmetry materials and interfaces. This is possible because, in these systems, spin-to-charge conversion can occur in unconventional configurations in which charge current, spin current, and polarization do not need to be mutually orthogonal. Here, we explore, in the low temperature regime, the spin-to-charge conversion in heterostructures of graphene with the low-symmetry 1T' phase of MoTe2. First, we observe the emergence of charge conversion for out-of-plane spins at temperatures below 100 K. This unconventional component is allowed by the symmetries of both MoTe2 and graphene and likely arises from spin Hall effect in the spin–orbit proximitized graphene. Moreover, we examine the low-temperature evolution of non-local voltage signals arising from the charge conversion of the two in-plane spin polarizations, which have been previously observed at higher temperature. As a result, we report omni-directional spin-to-charge conversion—for all spin polarization orientations—in graphene/MoTe2 heterostructures at low temperatures. [ABSTRACT FROM AUTHOR]

The generation of perpendicular effective magnetic field or perpendicular spins (σz) is central for the development of energy-efficient, scalable, and external-magnetic-field-free spintronic memory and computing technologies. Here, we report the first identification and the profound impacts of a significant effective perpendicular magnetic field that can arise from asymmetric current spreading within magnetic microstrips and Hall bars. This effective perpendicular magnetic field can exhibit all the three characteristics that have been widely assumed in the literature to "signify" the presence of a flow of σz, i.e., external-magnetic-field-free current switching of uniform perpendicular magnetization, a sin 2φ-dependent contribution in spin-torque ferromagnetic resonance signal of in-plane magnetization (φ is the angle of the external magnetic field with respect to the current), and a φ-independent but field-dependent contribution in the second harmonic Hall voltage of in-plane magnetization. This finding suggests that it is critical to include current spreading effects in the analyses of various spin polarizations and spin–orbit torques in the magnetic heterostructure. Technologically, our results provide a perpendicular effective magnetic field induced by asymmetric current spreading as a novel, universally accessible mechanism for efficient, scalable, and external-magnetic-field-free magnetization switching in memory and computing technologies. [ABSTRACT FROM AUTHOR]

The paper presents a novel composite material based on nanoporous AB-stacked bilayer graphene. The influence of the dopant atom on the electronic properties of the heterostructure and its position in the pore is investigated herein. The proposed effect is considered on composite materials doped with calcium and manganese atoms in order to correctly evaluate the influence of the valence shell filling type without the local field effect caused by the structural properties of an AB-stacked bilayer graphene. [ABSTRACT FROM AUTHOR]

Phosphorene is a graphene-like material with an intermediate band gap, in contrast to zero-gap graphene and large-gap dichalcogenides or hexagonal boron nitride (hBN), which makes it more suitable for nanoelectronic devices. However, inducing band-gap modulation in freestanding phosphorene nanoribbons (PNRs) is problematic, as high in-plane electric fields are necessary to close the gap. We perform here a detailed investigation concerning the substrate influence on the electric-field control exerted by an external gate, using the density functional theory–non-equilibrium Green's functions (DFT-NEGF) framework. It is established that the interaction with a hexagonal boron nitride supporting layer significantly enhances the gap modulation. Furthermore, we address the issue of contacting the PNRs, by using conducting graphene nanoribbons embedded in the support hBN layer. Within this setup, a measurable spin polarization is achieved owing to the anti-ferromagnetic coupling between the edges of the graphene nanoribbons. [ABSTRACT FROM AUTHOR]

The electronic and magnetic properties of KCaN 2 /KCl(001) heterojunction have been studied within the framework of density functional theory using the full-potential linear augmented plane waves plus local orbital approach. There are two possible interface layers depending on the crystal structure of KCaN 2. The results demonstrate that the half-metallicity nature remains in both possible interfaces, i.e., KCl/KCa and KCl/NN. Spin polarization in both interfaces is complete, % 100, and the interface effects do not affect half-metallicity. The Schottky barrier height, band offsets, valence band maximum, and conduction band minimum to these interfaces were calculated and compared with the other half-metal/semiconductor heterostructures. • Half-metallicity preserves at the both KCl/KCa and KCl/NN interfaces. • There are two types of band alignment for different interfaces: staggered type for NN/KCl and straddling type for KCa/KCl interfaces. • Potential lineups are obtained, Δ V KCa/KCl =0 18 eV and Δ V NN/KCl =1.05 eV. [Display omitted] [ABSTRACT FROM AUTHOR]

Two-dimensions Ruddlesden–Popper perovskites (RPPs) are promising materials for spintronic devices due to the spin–orbit coupling. However, a relative low spin related photoluminescence (PL) circular polarization is observed from RPPs at room temperature due to the spin relaxation and spin flip caused by the soft lattice of RPPs. Here, we report the enhancement of the circular polarization of PL of RPPs by reducing the carrier lifetime of RPPs via constructing van der Waals heterostructures. We observed the maximum PL polarization of RPPs reaching about 30%. Moreover, we found that the degree of the polarization decreases as the thickness of the heterostructure becomes thicker. Our work provides an effective method to enhance the spin polarization of RPPs and could promote the RPPs based spintronics. [ABSTRACT FROM AUTHOR]

Unique electronic spin textures in topological states of matter are promising for emerging spin-orbit driven memory and logic technologies. However, there are several challenges related to the enhancement of their performance, electrical gate-tunability, interference from trivial bulk states, and heterostructure interfaces. We address these challenges by integrating two-dimensional graphene with a three-dimensional topological insulator (TI) in van der Waals heterostructures to take advantage of their remarkable spintronic properties and engineer proximity-induced spin-charge conversion phenomena. In these heterostructures, we experimentally demonstrate a gate-tunable spin-galvanic effect (SGE) at room temperature, allowing for efficient conversion of a non-equilibrium spin polarization into a transverse charge current. Systematic measurements of SGE in various device geometries via a spin switch, spin precession, and magnetization rotation experiments establish the robustness of spin-charge conversion in the Gr-TI heterostructures. Importantly, using a gate voltage, we reveal a strong electric field tunability of both amplitude and sign of the spin-galvanic signal. These findings provide an efficient route for realizing all-electrical and gate-tunable spin-orbit technology using TIs and graphene in heterostructures, which can enhance the performance and reduce power dissipation in spintronic circuits. The spin-galvanic effect allows for the conversion of non-equilibrium spin density into a charge current. Here, by combining graphene in a van de Waals heterostructure with a topological insulator, the authors demonstrate a large, gate-tunable spin-galvanic effect. [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]

In this paper, a transition of magnetoresistance (MR) from positive to negative was obtained at room temperature by vacuum annealing of Fe 3 O 4 (128 nm) / Si (with natural SiO 2) heterostructures at 780 °C. Considering the wire-like nanograins with varying length and the effect of interface, the sign of MR is decided by the contribution of two Fe 3 O 4 layers. One is the layer at the Fe 3 O 4 /SiO 2 interface where the scattering of conducting electrons in the natural SiO 2 layer on the top of Si can lead to spin polarization reversal of Fe 3 O 4 and the other is the Fe 3 O 4 far away from the absorbing interface. The reversal sign of MR indicates the dominant contrition of Fe 3 O 4 far away from the absorbing interface as the stabilized SiO 2 phase on top of the Si substrate with fewer ion defects by annealing the Fe 3 O 4 film on natural Si at 780 °C. For the Fe 3 O 4 film prepared on the substrate of corroded Si (chemically etching the natural SiO 2 layer), positive MR is maintained even vacuum annealed at 780 °C, while for the Fe 3 O 4 film on SiO 2 , an additional α-Fe 2 O 3 phase is obtained even negative MR for films both as deposited and annealed at 780 °C. It can be concluded that the SiO 2 layer on top of the substrate plays an important role in the interface and then the magnetotransport properties of the Fe 3 O 4 heterostructures. Well property and negative spin polarization of Fe 3 O 4 film can be obtained by vacuum annealing the Fe 3 O 4 film on Si substrate with a proper thickness of natural SiO 2 layer at 780 °C. • Reversal of positive to negative MR at RT achieved by annealing Fe 3 O 4 /natural Si. • Stable SiO 2 layer prevent the reversal of spin polarization of Fe 3 O 4 to positive. • Comparing with Fe 3 O 4 on SiO 2 and Si with natural SiO 2 corroded respectively. • Preparing thick (128 nm) polycrystalline Fe 3 O 4 films on Si with desired properties. [ABSTRACT FROM AUTHOR]

The superconducting characteristics of the spin-valve Co2Cr1 - xFexAly/Cu/Ni/Cu/Pb heterostructures are studied. It is found that the difference in the plots characterizing superconducting transitions at the parallel and perpendicular orientations of magnetizations in the ferromagnetic Heusler alloy layer (HA = Co2Cr1 - xFexAly) with a high degree of spin polarization and in the nickel (Ni) layer can be as large as 0.5 K. For all samples, the dependence of Tc on the angle between the magnetization directions of the ferromagnetic layers exhibits a deep minimum near the orthogonal orientation. This minimum results from the long-range triplet components of the superconducting condensate in a ferromagnetic material. At the perpendicular orientation of the magnetizations, the Heusler alloy layer with the high degree of spin polarization absorbs the spin-polarized Cooper pairs from the spacing between the Heusler alloy and Ni layers. [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]

In this paper, we theoretically investigate how to control electron-spin polarization by δ-doping in a both magnetically and electrically confined semiconductor heterostructure. It is shown that, due to Zeeman coupling, a considerable spin polarization effect appears in the δ-doped device. It is also shown that both magnitude and sign of spin polarization can be tuned by changing weight or position of the δ-doping. Thus, a δ-doping controllable spin filter can be achieved for spintronics device applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Valley and spin polarization appear in the WS 2 /SrRuO 3 interface. • Valley and spin polarization can be attributed to the interfacial proximity. • Doping type and conductivity can be modulated as strain releases. Abstract The electronic structures of monolayer WS 2 on top of bilayer SrRuO 3 (1 1 1) are studied by first-principles calculations with spin-orbital coupling. The electronic properties can be influenced by stacking patterns of WS 2 /SrRuO 3 (1 1 1) heterostructures. Meanwhile, the valley polarization can be induced in monolayer WS 2 due to the broken time-reversal symmetry by the proximity to bilayer SrRuO 3 (1 1 1). With particular stacking patterns, larger valley splitting of monolayer WS 2 obtained in A1, A3, A4 and A5 models is 11.2, 11.3, 11.1 and 11.1 meV, respectively. Moreover, with biaxial strains, the conductivity of monolayer WS 2 can be effectively modulated. The Fermi level moves to a higher energy by appling tensile strains. Then the conductivity of WS 2 is governed by the valley states. In addition, the mechanical strains can modify the valley polarization and band gap effectively, showing potential applications in spintronic and valleytronic devices. [ABSTRACT FROM AUTHOR]

Abstract Based on first principles calculation method, we design and investigate the spin transport properties of two type heterostructures based on zigzag silicene nanoribbons (ZSiNRs). The first one consists of hydrogen-terminated ZSiNR (ZSiNR-H) and Rx-terminated ZSiNR (ZSiNR-Rx), here, Rx = O, S, P. The rectification behavior can be observed for heterostructures consisting of ZSiNR-H and ZSiNR-O (ZSiNR-S). The second one can be fabricated with a ZSiNR-Rx central scatter region between two ZSiNR-H electrodes. The results show that this device could maintain its good spin filtering effect for ZSiNR-O model in parallel (P) and antiparallel (AP) spin configuration with large bias range. Then we further investigate the spin-dependent transport with various length of ZSiNR-O region, and find that better spin filtering effect (near 100% spin polarization) can be observed for longer ZSiNR-O region. ZSiNR-S model show analogous spin filtering effect. However, neither rectification behavior nor spin filtering effect arise for ZSiNR-P models. Highlights • The constructure of two type heterostructures. • ZSiNR-O (ZSiNR-S) heterostructures show spin filtering effect or rectification behavior. • Neither rectification behavior nor spin filtering effect arise for ZSiNR-P models. [ABSTRACT FROM AUTHOR]

Abstract In this work, electrical manipulation of the magneto-optical properties of a cobalt (Co)/carbon (C) heterostructure is demonstrated via reversible voltage (V)-dependent magnetic circular dichroism (MCD) measurements to provide information on its spin-polarized density of states. Complex impedance spectroscopy revealed the occurrence of capacitance effects between Co and C. Suppression of the radial distribution functions of the X-ray absorption spectra and changes in the Raman spectra reveal that charge injection under an applied V results in increased interstitial charge densities. Angle-dependent changes in MCD under an applied V reveal that variations in C–Co hybridization due to charge accumulation are responsible for the observed phenomena. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Fe3O4 with high Curie temperature and 100% spin polarization is a potential candidate for practical applications in flexible spintronics. In this work, combined with flexible muscovite substrates, the dynamic strain influenced Verwey transition of Fe3O4 has been studied. The Verwey transition temperature increases (decreases) in the inward (outward) bending heterostructures. From the analyses of Fe L2,3 edge X-ray absorption spectroscopy, the reversible modulation originates from the charge reconstruction effect with the valence variations of Fe ions on the tetrahedral site and octahedral site in different bending states. Meanwhile, the charge reconstruction effect enhances the net magnetic moments of the Fe3O4/muscovite heterostructures in bending states. [ABSTRACT FROM AUTHOR]

The spin polarization features of an electron system and the relaxation of nonequilibrium spin excitations near an even-denominator fractional state of 3/2 in a two-dimensional electron system based on the GaAs/AlGaAs heterostructure are experimentally investigated. It is shown that the 3/2 state is a singular point in the filling factor dependence of the spin ordering of the two-dimensional electron system, at which the spin subsystem is rearranged. A giant slowing down of the relaxation of spin excitations to the ground state is revealed in a certain range of filling factors near filling factor 3/2. [ABSTRACT FROM AUTHOR]

Based on a magnetically confined GaAs/AlxGa1–xAs microstructure modulated by spin-orbit coupling (SOC), we propose a controllable electron-spin filter for spintronics applications. This device operates due to both Zeeman interaction and Rashba or Dresselhaus SOC. Its spin polarization can be tuned by changing interfacial confining electric field or engineering strain. [ABSTRACT FROM AUTHOR]

We propose a coaxial cylindrical quantum well wire which is composed of layers of a dilute magnetic semiconductor (DMS) and a nonmagnetic semiconductor (NMS). Using effective mass approximation, we present a numerical calculation of the eigenenergies and eigenstates of electrons in the heterostructure. The variation of the spin‐dependent energy levels is influenced by the giant Zeeman splitting and potential energies due to a vector potential for sufficiently low and high magnetic fields, respectively. It is found that crossing and anticrossing behaviors of energy levels can be controlled by the thickness of a NMS layer. The ballistic transport of the structure is also investigated. The ranges of the Fermi energy for obtaining full spin polarization are suggested in this work. [ABSTRACT FROM AUTHOR]

Abstract: The effects of the proximity contact with magnetic insulator on the spin‐dependent electronic structure of graphene are explored for the heterostructure of single‐layer graphene (SLG) and yttrium iron garnet Y3Fe5O12 (YIG) by means of outermost surface spin spectroscopy using a spin‐polarized metastable He atom beam. In the SLG/YIG heterostructure, the Dirac cone electrons of graphene are found to be negatively spin polarized in parallel to the minority spins of YIG with a large polarization degree, without giving rise to significant changes in the π band structure. Theoretical calculations reveal the electrostatic interfacial interactions providing a strong physical adhesion and the indirect exchange interaction causing the spin polarization of SLG at the interface with YIG. The Hall device of the SLG/YIG heterostructure exhibits a nonlinear Hall resistance attributable to the anomalous Hall effect, implying the extrinsic spin–orbit interactions as another manifestation of the proximity effect. [ABSTRACT FROM AUTHOR]

The magnetic field dynamics of intersubband collective excitations in two-dimensional electron systems based on MgZnO/ZnO heterostructures is studied by the Raman scattering method. It is found that, upon the change in the spin polarization under conditions of the transition from the filling factor ν = 2 to ν = 1, the energy of the intersubband magnetoplasmon changes considerably. The performed theoretical analysis shows that this effect is attributed to the concomitant change in the exchange interaction in the excitation energy. [ABSTRACT FROM AUTHOR]

We propose a mechanism for the generation of spin polarization in semiconductor heterostructures with a quantum well and a magnetic impurity layer spatially separated from it. The spin polarization of carriers in a quantum well originates from spin-dependent tunneling recombination at impurity states in the magnetic layer, which is accompanied by a fast linear increase in the degree of circular polarization of photoluminescence from the quantum well. Two situations are theoretically considered. In the first case, resonant tunneling to the spin-split sublevels of the impurity center occurs and spin polarization is caused by different populations of resonance levels in the quantum well for opposite spin projections. In the second, nonresonant case, the spin-split impurity level lies above the occupied states of electrons in the quantum well and plays the role of an intermediate state in the two-stage coherent spin-dependent recombination of an electron from the quantum well and a hole in the impurity layer. The developed theory allows us to explain both qualitatively and quantitatively the kinetics of photoexcited electrons in experiments with photoluminescence with time resolution in Mn-doped InGaAs heterostructures. [ABSTRACT FROM AUTHOR]

In the present work, we propose that a one-dimensional quantum heterostructure composed of magnetic and non-magnetic (NM) atomic sites can be utilized as a spin filter for a wide range of applied bias voltage. A simple tight-binding framework is given to describe the conducting junction where the heterostructure is coupled to two semi-infinite one-dimensional NM electrodes. Based on transfer matrix method, all the calculations are performed numerically which describe two-terminal spin-dependent transmission probability along with junction current through the wire. Our detailed analysis may provide fundamental aspects of selective spin transport phenomena in one-dimensional heterostructures at nanoscale level. [ABSTRACT FROM AUTHOR]

We theoretically study how magnetic modulation can be used to manipulate the transport properties of heterostructures formed by a thin film of a three-dimensional topological insulator sandwiched between slabs of a normal insulator. Employing the k ∙ p scheme, in the framework of a continual approach, we argue that electron states of the system are spin-polarized when ultrathin magnetic insertions are incorporated into the film. We demonstrate that (i) the spin-polarization magnitude depends strongly on the magnetic insertion position in the film and (ii) there is the optimal insertion position to realize quantum anomalous Hall effect, which is a function of the material parameters, the film thickness and the topological insulator/normal insulator interface potential. For the heterostructure with a pair of symmetrically placed magnetic insertions, we calculate a phase diagram that shows a series of transitions between distinct quantum regimes of transverse conductivity. We provide consistent interpretation of recent experimental findings in the context of our results. [ABSTRACT FROM AUTHOR]

Spin-polarized density functional theory is used to study the TiO2 terminated interfaces between the magnetic Heusler alloys Co2Si ( M = Ti, V, Cr, Mn, and Fe) and the non-polar band insulator SrTiO3. The structural relaxation at the interface turns out to depend systematically on the lattice mis- match. Charge transfer from the Heusler alloys (mainly the M 3d orbitals) to the Ti d xy orbitals of the TiO2 interface layer is found to gradually grow from M = Ti to Fe, resulting in an electron gas with increasing density of spin-polarized charge carriers. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Extreme points on potential energy surfaces of Ni adatom on free-standing graphene and top:fcc and hcp:fcc graphene/ Ni(111) heterostructures in different spin states were studied using periodic boundary conditions density functional theory approach. It was found that the spin states of the substrates strongly influence the energy of the Ni adatom extreme points on potential energy surface by decreasing (top:fcc heterostructure) or increasing (hcp:fcc heterostructure) the total energies of η1, η1', and η2 Ni adatom coordinations on graphene. This phenomenon offers unique possibilities to control the potential energy surfaces of transition metal adatoms and promote surface chemical reactions using induced spin polarization of graphene substrates. [ABSTRACT FROM AUTHOR]

The electron tunneling through a nonmagnetic heterostructure modulated by both the in-plane magnetic field and the δ -doping has been investigated in detail using the transfer-matrix method. The numerical results indicate that, in such a nonmagnetic device, one can obtain the considerable spin polarization which is dependent on the in-plane magnetic field and the δ -doping as well as the wave vector in the plane of the barrier. Thus, we can design the spintronic devices based on nonmagnetic heterostructures controlled by the in-plane magnetic field and the δ -doping as well as the wave vector. [ABSTRACT FROM AUTHOR]

We simulate the electron transport in a vertical bi-layer nanowire in order to study an influence of the lateral confinement's shape on a spin polarization of wire's conductance. The active part of considered quantum wire constitutes a double inverted heterojunction In 0.52 Al 0.48 As / In 0.53 Ga 0.47 As which nanostructure can be fabricated in molecular beam epitaxy process while the lateral confinement potential can be finally formed by means of cleaved overgrowth or surface oxidization methods giving the desired rectangular and smooth lateral confinement. In calculations we take into account interaction between charge carriers using DFT within local spin density approximation. We show that if the magnetic field is perpendicular to the wire axis, the pseudogaps are opened in energy dispersion relation E ( k ) what in conjunction with spin Zeeman shift of spin-up and spin-down subbands may enhance the spin polarization of conductance with reference to a single layer wire. For nanowire with rectangular lateral confinement potential we found that the electron density has two maximums localized at wire edges in each layers. This modificates strongly all magnetosubbands giving up to four energy minimums in lowest subband and considerably diminishes widths of pseudogaps what translates into low maximal spin polarization of conductance, not exceeding 40%. This drawback is absent in wire with smooth lateral confinement. However, in order to gain a large spin polarization simultaneous tuning of magnetic field as well as the Fermi energies in both layers of nanowire are required. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides exhibit spin-orbit split bands at the K-point that become spin polarized for broken crystal inversion symmetry. This enables simultaneous manipulation of valley and spin degrees of freedom. While the inversion symmetry is broken for monolayers, we show here that spin polarization of the MoS2 surface may also be obtained by interfacing it with graphene, which induces a space charge region in the surface of MoS2. Polarization induced symmetry breaking in the potential gradient of the space charge is considered to be responsible for the observed spin polarization. In addition to spin polarization we also observe a renormalization of the valence band maximum (VBM) upon interfacing of MoS2 with graphene. The energy difference between the VBM at the G-point and K-point shifts by ~150 meV between the clean and graphene covered surface. [ABSTRACT FROM AUTHOR]

We present the Usadel theory describing the superconducting proximity effect in heterostructures with a half-metallic layer. It is shown that the full spin polarization inside the half-metals gives rise to an additional component of the Green's function which results in the giant triplet spin-valve effect in superconductor (S)-ferromagnet (F)-half-metal (HM) trilayers and provides a natural explanation for the φ0-junction formation in the S/F/HM/F/S systems. In addition, we consider the exactly solvable model of the S/F/HM trilayers of atomic thickness and demonstrate that it reproduces the main features of the spin-valve effect found within the Usadel approach. Our results are shown to be in qualitative agreement with the recent experimental data on the spin-valve effect in MoGe/Ni/Cu/CrO2 hybrids [Singh et al., Phys. Rev. X 5, 021019 (2015)]. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the spin-dependent electron transport in a nonmagnetic nanostructure under the influence of the -doping which can be experimentally doped in the nanostructure with metal-organic chemical vapor deposition or molecular beam epitaxy. The numerical results indicate that the large spin polarization nearly 100% can be achieved in such a structure without the external magnetic field due to spin-orbit interactions and it can be controlled not only by the barrier, but also by the -doping. These interesting finds are very valuable for designing the -doping-tunable spintronic device based on the nonmagnetic nanostructure. [ABSTRACT FROM AUTHOR]

Spin-dependent electronic transport through multiferroic Co/PbTiO3/Co tunnel junctions is studied theoretically in view of the recent observation of an inverse TMR in Co/PbTiO3/LaSrMnO3 heterostructures. Conductances calculated within the Landauer-Büttiker formalism yield a four-conductance state characterized by sizable positive tunnel magnetoresistances (TMR) and tunnel electroresistances (TER). The conductances depend crucially on the details of the electronic structure at the interfaces. In particular, the spin polarization of the tunneling electronic states is affected by the hybridization of orbitals and the associated charge transfer at both interfaces. Digital doping of the PbTiO3 barrier with Zr impurities at the TiO2/Co2 interface removes the excessive metalization of the barrier and significantly enhances the TMR but is not sufficient to switch the TMR's sign. Our results indicate that the origin of the TMR inversion might be attributed to the magnetoelectrically active LaSrMnO3/PbZr0.2Ti0.8O3 interface. [ABSTRACT FROM AUTHOR]

We propose a method to compute the transmission through correlated heterostructures by combining density functional and many-body dynamical mean field theories. The heart of this combination consists in porting the many-body self-energy from an all electron basis into a pseudopotential localized atomic basis set. Using this combination we study the effects of local electronic interactions and finite temperatures on the transmission across the Cu4CoCu4 metallic heterostructure. It is shown that as the electronic correlations are taken into account via a local but dynamic self-energy, the total transmission at the Fermi level gets reduced (predominantly in the minority-spin channel), whereby the spin polarization of the transmission increases. The latter is due to a more significant d-electron contribution, as compared to the noncorrelated case in which the transport is dominated by s and p electrons. [ABSTRACT FROM AUTHOR]

The coupling of spin and valley physics is nowadays regarded as a promising route toward next-generation spintronic and valleytronic devices. In the aim of engineering functional properties for valleytronic applications, we focus on the ferroelectric heterostructure BiAlO3/BiIrO3, where the complex interplay among a trigonal crystal field, layer degrees of freedom, and spin-orbit coupling mediates a strong spin-valley coupling. Furthermore, we show that ferroelectricity provides a nonvolatile handle to manipulate and switch the emerging valley-contrasting spin polarization. [ABSTRACT FROM AUTHOR]

We report on a theoretical investigation of spin-polarized transport in a δ -doped magnetically modulated semiconductor nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the top of a semiconductor heterostructure and by using the atomic layer doping technique such as molecular beam epitaxy (MBE). It is shown that although such a nanostructure has a zero average magnetic filed, a sizable spin polarization exists due to the Zeeman splitting mechanism. It is also shown that the degree of spin polarization varies sensitively with the weight and/or position of the δ -doping. Therefore, one can conveniently tailor the behaviour of the spin-polarized electron by tuning the δ -doping, and such a device can be employed as a controllable spin filter for spintronics. [ABSTRACT FROM AUTHOR]

We theoretically investigate the electron transport properties in a non-magnetic nanostructure with spin–orbit interactions and the δ -doping which can be experimentally realized by using metal-organic chemical-vapor deposition or molecular beam epitaxy. We find that the electron transmission and the spin polarization strongly depend not only on the height and the width of the barrier but also on the weight and the position of the δ -doping. These interesting phenomena may be very helpful for understanding the electron transport mechanism in a non-magnetic nanostructure and designing the δ -doping-tunable spintronic device based on the non-magnetic heterostructure. [ABSTRACT FROM AUTHOR]

In this paper, we study the spin-dependent electron transmission through a quantum well in semiconductor heterostructures with dipole-type oscillation field and homogeneous oscillation field. The numerical evaluations show that Dresselhaus spin-orbit coupling eliminates the spin degeneracy and leads to the splitting of asymmetric Fano-type resonance peaks in the transmissivity. The width of the splitting peaks is found to be highly sensitive to the direction of incident electron. The dipole modulation and the homogeneous modulation is approximately equivalent under certain conditions. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents by the more practical dipole-type oscillation in the experimental setup. [ABSTRACT FROM AUTHOR]

We report a theoretical study on spin-polarized lateral displacement for the electron across a magnetic nanostructure with a zero average magnetic field, which can be experimentally realized by depositing a ferromagnetic stripe with a plumb magnetization on the top of a semiconductor heterostructure. It is shown that, the lateral displacement depends strongly on the electron spins due to the Zeeman coupling and the intrinsic symmetry, though the average magnetic field is vanishing in the nanostructure. It is also shown that the spin-polarized lateral displacement is related closely to the structural parameters. Therefore, such a novel magnetic nanostructure may be used as a spin spatial splitter for spintronics applications. [ABSTRACT FROM AUTHOR]

A conceptual metallic/semiconducting TaB2/Ta2O5 core/shell heterostructure exhibits a substantial improvement in photocatalytic hydrogen evolution rate under both UV and visible light. TaB2 plays a dual role in boosting the photocatalytic activity by extending the light‐absorption range via efficient interfacial electronic modification and by promoting the separation and transfer of photoexcited charge carriers by using metallic TaB2 core as an electron collector. [ABSTRACT FROM AUTHOR]

In heterostructures based on AB and AB semiconductors doped with transition metals, viz., GaSb(59%)-MnSb(41%), GaAs/InGaAs/GaAs/GaAs:Mn, and ZnSe/ZnMgSSe/ZnSSe:Cr, we observe effects caused by the influence of charge carriers on magnetic properties and reverse effects consisting of a change in the electric and optical properties of the heterostructure caused by ferromagnetic ordering. Spin polarization of the charge carriers is the principal condition for establishing an interrelation of magnetic and other properties of magnetic semiconductor heterostructures. [ABSTRACT FROM AUTHOR]

Transition-metal heterostructures offer the fascinating possibility of controlling orbital degrees of freedom via strain. Here, we investigate theoretically the degree of orbital polarization that can be induced by epitaxial strain in LaNi03 films. Using combined electronic structure and dynamical mean-field theory methods we take into account both structural distortions and electron correlations and discuss their relative influence. We confirm that Hund's rule coupling tends to decrease the polarization and point out that this applies to both the dgL and d7 local configurations of the Ni ions. Our calculations are in good agreement with recent experiments, which revealed sizable orbital polarization under tensile strain. We discuss why full orbital polarization is hard to achieve in this specific system and emphasize the general limitations that must be overcome to achieve this goal. [ABSTRACT FROM AUTHOR]