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We investigate collisionless shock acceleration of spin-polarized 3 He for laser pulses with normalized vector potentials in the range a 0 = 100 − 200 . The setup utilized in the 2D-particle-in-cell simulations consists of a solid carbon foil that is placed in front of the main Helium target. The foil is heated by the laser pulse and shields the Helium from the highly oscillating fields. In turn, a shock wave with more homogeneous fields is induced, leading to highly polarized ion beams. We observe that the inclusion of radiation reaction into our simulations leads to a higher beam charge without affecting the polarization degree to a significant extent. [ABSTRACT FROM AUTHOR]

The spin superconductor state is the spin-polarized triplet exciton condensate, which can be viewed as a counterpart of the charge superconductor state. As an analogy of the charge Josephson effect, the spin Josephson effect can be generated in the spin superconductor/normal metal/spin superconductor junctions. Here we study the spin supercurrent in the Josephson junctions consisting of two spin superconductors with noncollinear spin polarizations. For the Josephson junctions with out-of-plane spin polarizations, the possible π -state spin supercurrent appears due to the Fermi momentum-splitting Andreev-like reflections at the normal metal/spin superconductor interfaces. For the Josephson junctions with in-plane spin polarizations, the anomalous spin supercurrent appears and is driven by the misorientation angle of the in-plane polarizations. The symmetry analysis shows that the appearance of the anomalous spin Josephson current is possible when the combined symmetry of the spin rotation and the time reversal is broken. [ABSTRACT FROM AUTHOR]

The photogalvanic effects (PGEs) in low-dimensional devices have attracted great interests recently. Herein, based on non-equilibrium Green's function combined with density functional theory, we investigated spin-dependent PGE phenomena in the BiC photodetector with the linearly polarized light and zero bias. Due to the presence of strong spin–orbit interaction (SOI) and C 3 v symmetry for the BiC monolayer, the armchair and zigzag BiC photodetectors can produce robust spin-dependent PGEs which possess the cos(2 θ) and sin(2 θ) relations on the photon energies, respectively. Especially, the pristine armchair and armchair Bi-vacancy BiC photodetectors can produce fully spin polarization, and pure spin current was found in the pristine armchair and zigzag BiC photodetector, respectively. Furthermore, after introducing the Bi-vacancy, C-vacancy, Bi-doping and C-doping respectively, the BiC photodetector can produce higher spin-dependent PGEs for their C s symmetry. Additionally, the behaviors of spin-dependent photoresponse are highly anisotropic which can be tuned by the photon energy. This work suggested great potential applications of the BiC monolayer on PGE-driven photodetectors in low energy-consumption optoelectronics and spintronic devices. [ABSTRACT FROM AUTHOR]

Inner edge state with spin and valley degrees of freedom is a promising candidate for designing a dissipationless device due to the topological protection. The central challenge for the application of the inner edge state is to generate and modulate the polarized currents. In this work, we discover a new mechanism to generate fully valley- and spin–valley-polarized current caused by the Bloch wavevector mismatch (BWM). Based on this mechanism, we design some serial-typed inner-edge filters. By using once of the BWM, the coincident states could be divided into transmitted and reflected modes, which can serve as a valley or spin–valley filter. In particular, while with twice of the BWM, the incident current is absolutely reflected to support an off state with a specified valley and spin, which is different from the gap effect. These findings give rise to a new platform for designing valleytronics and spin-valleytronics. [ABSTRACT FROM AUTHOR]

Non-Hermitian (NH) quantum system recently have attracted a lots of attentions theoretically and experimentally. However, the results based on the single-particle picture may not apply to understand the property of NH many-body system. How the property of quantum many-body system especially the phase transition will be affected by the non-Hermiticity remains unclear. Here we study NH quantum contact process (QCP) model, whose effective Hamiltonian is derived from Lindbladian master equation. We show that there is a continuous phase transition induced by the non-Hermiticity in QCP. We also determine the critical exponents β of order parameter, γ of susceptibility and study the correlation and entanglement near phase transition point. We observe that the order parameter and susceptibility display infinitely singularity even for finite size system, since non-Hermiticity endow many-body system with different singular behavior from classical phase transition. Moreover our results show that the phase transition have no counterpart in Hermitian case and belongs to completely different universality class. [ABSTRACT FROM AUTHOR]

In this work, we theoretically investigate the phenomenon of spin polarization in generalized Sierpinski gasket (SPG) triangles ( Δ N N N , Δ F N N , Δ F F N , Δ F F F) in the presence of Rashba spin–orbit interaction (RSOI) within a tight-binding framework. The geometrical construction is addressed for all four types of generalized SPG triangles using an iterative function system that begins with a fixed triangle of any arbitrary side length. The geometry of various types of fractal networks has a major impact on the degeneracy of the energy spectrum. It is shown that only the two-terminal setup in the presence of RSOI is incapable of breaking the spin degeneracy, which necessitates the use of a three-terminal setup to break the time-reversal symmetry. The effect of flip map induced anisotropic hopping integrals on three-terminal spin-resolved transmission probabilities is studied. In several cases, we find almost 100 % spin polarization in our considered lattices. We also analyze how spin polarization varies with RSOI strength and fractal generations. Our results indicate that fractal lattices might be suitable functional elements for designing future spin-based electronic devices. [ABSTRACT FROM AUTHOR]

We have theoretically investigated the Andreev reflection (AR)-induced conductance spectra through antiferromagnet/normal layer/superconductor junctions with hexagonal lattices. When the PT symmetry is broken by the staggered sublattice potential, antiferromagnet may exhibit spin polarization. A gap-edge conductance peak is usually shown, reflecting the characteristic of conventional AR. Equal-spin AR can be generated by the spin-flip scattering caused by Rashba spin–orbit coupling in the normal layer. Surprisingly, when the equal-spin AR process dominates, the conductance peak divides into two peaks near the singlet-gap energy, indicating the existence of spin-triplet pairings in the antiferromagnet. Furthermore, as the amplitudes of the conventional and equal-spin ARs can be modulated by the staggered sublattice potential and electrostatic potential, a conversion from the conductance peak to the conductance peak splitting can be realized, which can help us to distinguish between the spin-singlet and spin-triplet pairings. These findings make the antiferromagnet/superconductor junctions as promising platforms for future superconducting spintronics applications. [ABSTRACT FROM AUTHOR]

Inspired by potential application prospects of spintronics and valleytronics, a novel heterobilayer Janus structure is designed by replacing the chalcogenide atomic layers in the original bilayer MoS2. Based on first-principles calculations, it is found that the SMoS/SeMoS structure exhibits a direct band-gap semiconductor and a typical type-II band alignment with longer carrier lifetime. The transition metal (TM) atom represented by V/Cr/Mn can be stably adsorbed on the heterobilayer Janus SMoS/SeMoS sheet and effectively introduce magnetic moments (m). The calculation results demonstrate that the most stable adsorption site of the TM atom is CX(A), and the TM (V/Cr/Mn) adatom modified SMoS/SeMoS system is converted into metal (V-) or half-metal (Cr/Mn-), respectively. Under the coupling of different indirect exchange interactions, the structure exhibits stable intrinsic anti-ferromagnetic interactions for V-SMoS/SeMoS and ferromagnetic ground state for Cr/Mn-SMoS/SeMoS, respectively, and the magnetic transition temperature (T c) reaches a high temperature or even room temperature. Moreover, the robust out-of-plane magnetocrystalline anisotropy energy ensures stable long-range magnetic order. Specifically, the combination of spin injection and strong spin–orbit coupling interaction effectively breaks the time-reversal symmetry, which leads to valley polarization of the system. Based on this, the biaxial strain can effectively regulate the electronic structure, magnetic properties and valley polarization of TM-SMoS/SeMoS nanosheets with double breaking of spatial-inversion and time-reversal symmetry. [ABSTRACT FROM AUTHOR]

Analysis of ponderomotive effects exciting from propagation of an intense laser pulse through high density quantum plasma under the influence of an axial magnetic field taking into consideration the spin–spin (up and down) exchange interaction. The effects of electron Fermi pressure, quantum Bohm potential, and electron spin have been included in the analysis. Spin polarization is a result of the concentration difference of opposite spin electrons which is produced under the influence of the applied magnetic field. Axial gradient of the ponderomotive potential of laser has been applied for the electron acceleration. An analytic solution of the electron energy gain is obtained and the influence of spin polarization is analyzed both numerically and analytically. It is observed that spin polarization, density perturbation and the magnetic field effect electron acceleration dramatically. Further, the effect of nonlinearity on the refractive index of plasma has been studied. [ABSTRACT FROM AUTHOR]

Defects play significant roles in spin-current-related physical processes in intrinsic ferromagnetic semiconductors (FMSs), which are great promise for spintronics applications. However, current defect calculation methods cannot be used to investigate charged defects in FMSs due to the spin polarization of both the charged defect states and ionized carriers, which is not well treated in current defect calculation methods. In order to solve this problem, we propose a spin-distinguishable charge correction (SDCC) method that uses spin-polarized band edge charge density instead of spin-unpolarized uniform background charge density as the compensating charge for charged defects. We apply our method to study the defect properties of CrI3 monolayer and find it can be doped n-type under the Cr-rich growth condition but difficult to be doped p-type. The SDCC method proposed here is generally suitable for all FMSs, which will be useful for the studies of defect properties of magnetic semiconductors. [ABSTRACT FROM AUTHOR]

Defects play significant roles in spin-current-related physical processes in intrinsic ferromagnetic semiconductors (FMSs), which are great promise for spintronics applications. However, current defect calculation methods cannot be used to investigate charged defects in FMSs due to the spin polarization of both the charged defect states and ionized carriers, which is not well treated in current defect calculation methods. In order to solve this problem, we propose a spin-distinguishable charge correction (SDCC) method that uses spin-polarized band edge charge density instead of spin-unpolarized uniform background charge density as the compensating charge for charged defects. We apply our method to study the defect properties of CrI3 monolayer and find it can be doped n-type under the Cr-rich growth condition but difficult to be doped p-type. The SDCC method proposed here is generally suitable for all FMSs, which will be useful for the studies of defect properties of magnetic semiconductors. [ABSTRACT FROM AUTHOR]

Spin-exchange relaxation-free (SERF) co-magnetometers have promising applications in both inertial navigation and fundamental physics experiments. However, the fluctuation in the spin polarization caused by the probe beam has a non-negligible influence on the co-magnetometer signal. In this paper, a theoretical model containing three parameters of the probe beam is established by extending the coupled Bloch equation. Based on this model, the influence of probe power density on the transient and steady-state response of the SERF co-magnetometer is analyzed. According to the transient response model, a new measurement method for transverse optical pumping of the probe beam is proposed. Then, for the steady-state response model, a steady-state error suppression method is suggested by adjusting the degree of circular polarization of the probe beam. Eventually, the suppression method is used to refine the SERF co-magnetometer, achieving a suppression rate of 70.31% in transverse electron spin polarization fluctuations, thus improving the co-magnetometer to a stability of 0.0079∘ h−1. To our knowledge, this is better than what has been reported so far. [ABSTRACT FROM AUTHOR]

Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics. Here, by using spin- and angle-resolved photoemission spectroscopy, we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi2Sr2CaCu2O8+ δ and discover the anisotropy of spin polarizations at nodes along Γ – X and Γ – Y directions. The breaking of C 4 rotational symmetry in electronic spin texture may give deeper insights into understanding the ground state of cuprate superconductors. [ABSTRACT FROM AUTHOR]

Seeking new order parameters and the related broken symmetry and studying their relationship with phase transition have been important topics in condensed matter physics. Here, by using spin- and angle-resolved photoemission spectroscopy, we confirm the helical spin texture caused by spin-layer locking in the nodal region in the cuprate superconductor Bi2Sr2CaCu2O8+ δ and discover the anisotropy of spin polarizations at nodes along Γ – X and Γ – Y directions. The breaking of C 4 rotational symmetry in electronic spin texture may give deeper insights into understanding the ground state of cuprate superconductors. [ABSTRACT FROM AUTHOR]

Since the first evidence of a global polarization of Λ hyperons in relativistic nuclear collisions in 2017, spin has opened a new window in the field, both at experimental and theoretical level, and an exciting perspective. The current state of the field is reviewed with regard to the theoretical understanding of the data, reporting on the most recent achievements and envisioning possible developments. The intriguing connections of spin physics in relativistic matter with fundamental questions in quantum field theory and applications in the non-relativistic domain are discussed. [ABSTRACT FROM AUTHOR]

We study inserting Co layer thickness-dependent spin transport and spinâ€"orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density (K s = 2.7 erg/cm2, 1 erg = 10âˆ'7 J), which is dominated by interfacial spinâ€"orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance (G eff , tot â†' â†" = 0. 42 Ă— 10 15 Ω âˆ' 1 â‹... m âˆ' 2 ) and two-magnon scattering (β TMS = 0.46 nm2) are first characterized, and the damping-like torque (Îľ DL = 0.103) and field-like torque (Îľ FL = â€"0.017) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of Îľ DL and Îľ FL in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashbaâ€"Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface. [ABSTRACT FROM AUTHOR]

We employ the Dirac cone model to explore the high Chern number (C) phases that are realized in the magnetic-doped topological insulator (TI) multilayer structures by Zhao et al. [ Nature 588 419 (2020)]. The Chern number is calculated by capturing the evolution of the phase boundaries with the parameters, then the Chern number phase diagrams of the TI multilayer structures are obtained. The high- C behavior is attributed to the band inversion of the renormalized Dirac cones, along with which the spin polarization at the Î" point will get increased. Moreover, another two TI multilayer structures as well as the TI superlattice structures are studied. [ABSTRACT FROM AUTHOR]

We investigated the Ge-composition (Îł) dependence of the saturation magnetization of Co2Fe(Ga, Ge) (CFGG) thin films and the magnetoresistance (MR) ratio of CFGG-based current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices together with first-principles calculations of the electronic states of CFGG. Theoretical calculations showed that spin polarization is highest at the stoichiometric composition Îł = 0.56 in Co2Fe1.03Ga0.41Ge Îł and that it decreases in off-stoichiometric CFGG, mainly due to the formation of CoFe antisites for Ge-deficient compositions and FeCo antisites for Ge-rich compositions, where CoFe (FeCo) indicates that Co (Fe) atoms replace the Fe (Co) sites. The saturation magnetic moment (ÎĽ s) per formula unit decreased monotonically as Îł increased from 0.24 to 1.54 in Co2Fe1.03Ga0.41Ge Îł. The ÎĽ s was closest to the Slaterâ€"Pauling value predicted for half-metallic CFGG at the stoichiometric composition Îł = 0.56, indicating that stoichiometric CFGG has a half-metallic nature. This is consistent with the result for the theoretical spin polarization. In contrast, the MR ratio of CFGG-based CPP-GMR devices increased monotonically as Îł increased from 0.24 to 1.10 and reached an MR ratio of 87.9% at the Ge-rich composition Îł = 1.10. Then, the MR ratio decreased rapidly as Îł increased from 1.10 to 1.48. Possible origins for the slight difference between the Ge composition at which the highest MR ratio was obtained (Îł = 1.10) and that at which the highest spin polarization was obtained (Îł = 0.56) are improved atomic arrangements in a Ge-rich CFGG film and the reduction of effective Ge composition due to Ge diffusion in the GMR stacks. [ABSTRACT FROM AUTHOR]

The development of two-dimensional (2D) magnetic semiconductors promotes the study of nonvolatile control of magnetoelectric nanodevices. MnBi2Te4 is the first realization of antiferromagnetic topological insulator. In semiconductor circuits, metal-semiconductor contacts are usually essential. In future all-carbon circuits, graphene is a promising material for 2D conductive connections. This work studies electronic transport through graphene-MnBi2Te4-graphene junctions. We find that graphene-MnBi2Te4 interfaces are perfect Ohmic contacts, which benefits the use of MnBi2Te4 in carbon circuits. The currents through MnBi2Te4 junctions possess high spin polarization. Compared with usual van der Waals junctions, lateral graphene-MnBi2Te4-graphene junctions present a lower barrier and much higher conductance to electrons. These findings may provide guidance for further study of 2D spin filtering. [ABSTRACT FROM AUTHOR]

We present a comparative study of differential cross sections (DCSs) and spin polarizations for positron scattering from C60 and A@C60, elucidating the role of encapsulation of rare gas atoms inside the giant C60 cage. A comparison is provided with the earlier work for elastic positron-C60 scattering. We find a very good agreement even when a model potential is used for the positron-C60 interaction. Also, we evaluate similarities and differences between the positron and electron DCSs and spin polarizations, both from bare and endohedral targets. To mark resonance features on the scattering dynamics, DCSs and spin polarizations are calculated at resonant energies, which showcase different characteristics compared to the cases where the positron energy is non-resonant. In order to account for a complete picture of the scattering process, an absorption potential is included in the total scattering field. For the sake of illustrating the impact of individual interactions and their interplay as a whole, DCSs and spin polarizations are reported including several scattering interactions alternatively. [ABSTRACT FROM AUTHOR]

We study the symmetry of spin transport in graphene with the Rashba spin–orbit coupling (SOC) and the staggered potential, which can be produced by depositing the graphene on a transition-metal dichalcogenides substrate. The results show that all three spin polarization components along the x , y and z directions are achieved with a measurable conductance in such a nonmagnetic graphene. The spin transport property near the two valleys is discussed in the light of the symmetry of the system. Both conductance and spin polarization present some certain symmetries with respect to the Rashba SOC (RSOC) and staggered potential. The system could work as a valley-spin polarization transverter which combines valleytronics and spintronics. Furthermore, the asymmetric Fano–Rashba resonance of the conductance and spin polarization could occur in a resonant structure due to interference of spin-polarized discrete and continuum states induced by the RSOC. The Fano–Rashba resonance can be effectively controlled by the gate voltage. The derived symmetry relations and numerical results could provide a guideline for the design of spin-valley-based devices.

A new writing scheme with a unidirectional pulse current is proposed for spin transfer torque (STT) based magnetic random-access memory (MRAM). To investigate the feasibility of the writing scheme, bilayered nano-pillars composed of a soft layer with small in-plane shape anisotropy and a hard layer with either large perpendicular anisotropy (PMA) or in-plane anisotropy (IMA) are designed and their switching behaviors are studied. It is found that in either type of bilayered nano-pillars, with the aid of the attached hard layer, the magnetization of the soft layer can be switched back and forth under a unidirectional pulse current. In an IMA/IMA nano-pillar, the magnetization of the free layer (FL) can achieve excellent alignment, which is in contrast to the IMA/PMA nano-pillar. By optimizing the dimensions and magnetic parameters of the IMA/IMA nano-pillar, a decently low switching current density (4.3 × 1011 A mâˆ'2) and ultrashort switching time (<1 ns) can be reached. Based on these results, the unidirectional writing scheme is practical if an IMA/IMA bilayer is used to replace the FL in a magnetic tunnel junction. Considering that a unidirectional writing scheme can enable the application of materials with high spin polarization such as half metals, and avoid the injection of writing current into junction using a special design, it may be very promising for STT-MRAM. [ABSTRACT FROM AUTHOR]

The impact of inter-valley scattering in modifying the density of optically injected spin polarized electrons in AlxGa1−xAs/GaAs heterostructure is investigated. Polarization resolved photoluminescence excitation measurements are performed for studying the spectral dependence of degree of circular polarization (DCP) of photoluminescence signal emanating from an adjacent quantum well layer. The experimental DCP spectra is found to deviate from the theoretically calculated curve at high excitation energy and the deviation is seen to widen with the Al-content of AlxGa1−xAs barrier layer. In the past, researchers had attributed similar deviations to the Dyakonov–Perel (DP) spin relaxation mechanism which dominates the electrons spin dynamics at high excitation energy. However, we find that the inter-valley scattering along with the DP mechanism decide the shape of optical spin orientation spectra at higher energy. In fact, at higher Al-content, the inter-valley scattering in AlxGa1–xAs layer becomes the most dominant mechanism to govern the steady state electron spin polarization at the band edge. A numerical model is also proposed for estimating the steady state electron spin polarization at zone centre by including the inter-valley scattering, energy relaxation and DP spin relaxation mechanisms. [ABSTRACT FROM AUTHOR]

Helical functionalization of carbon nanotubes using DNA strands can polarize carrier spins through chirality induced spin selectivity (or CISS) effect. Detection of this effect using transport experiments unravels an underlying magnetoresistance effect, origin of which is not well understood. In the present study, we investigate this effect, a fundamental understanding of which is crucial for the potential use of this system in spintronic devices. The conduction mechanism has been found to be in the strongly localized regime due to DNA functionalization, with the observed magnetoresistance originating from the interference effects between the forward and backward hopping paths. CISS-induced spin polarization has been estimated to increase the carrier localization length by an order of magnitude in the low temperature range and it affects the magnetoresistance effect in a non-trivial way that is not observed in conventional systems. [ABSTRACT FROM AUTHOR]

Perfect polarization of spin and valley is found to coexist in the proposed junction of monolayer MoS2. The junction consists of two barriers modulated by off-resonant circularly polarized light and spin Zeeman field, respectively. By appropriately altering the modulation, we can achieve all four combinations of simultaneous perfect spin and valley polarization, which are , , , and. Moreover, we have found that by continuously tuning the light illuminating the junction, the valley polarization will abruptly dive from 100% to −100%. The spin polarization exhibits similar features when we tune the spin Zeeman field. Thus, the valley switching effect and the spin switching effect are realized in monolayer MoS2 by varying the circularly polarized light and spin Zeeman field. These results demonstrate the modulated monolayer MoS2's potential as a vital tool in spintronics and valleytronics. [ABSTRACT FROM AUTHOR]

We investigate the spin-related currents and tunnel magnetoresistance through a quantum dot, which is side-coupled with a Majorana fermion zero mode and two thermal-driven ferromagnetic electrodes. It is found that the interplay of Majorana fermion and electrodes' spin polarization can induce a nonlinear thermal-bias spin current. This interplay also decreases the total magnitude of spin or charge current, in either parallel or antiparallel configuration. In addition, a thermal-driven negative tunnel magnetoresistance is found, which is an unique feature to characterize Majorana fermion. With large temperature difference, a step phenomenon is observed in gate tuned spin-up current. When the coupling between quantum dot and topological superconductor is strong enough, this step will evolve into a linear relation, revealing Majorana fermion's robustness. [ABSTRACT FROM AUTHOR]

Eu-doped rare earth sesquioxides RE2O3:Eu (RE = Lu, Y, Sc) exhibit subtle difference in scintillation processes, for which impurity levels play an important role but are difficult to assess computationally due to localized f-electrons and itinerant spd-electrons in the materials. Unpaired electrons of dopant Eu3+ ions also render complexity to these systems. In this study we calculated band structures of pure and Eu-doped RE2O3 using quasi-particle GW approximation with collinear spin polarization based on density functional theory. The band structures were similar across the three host material systems, varying with spin component and dopant's lattice site. Only the majority-spin states are responsible for the scintillation process, whereas the minority-spin states are entangled with the hosts' low-energy conduction bands. The materials' afterglow behavior was explained in terms of the positions of 4f orbitals and electron traps, as well as thermodynamics of the doping systems. [ABSTRACT FROM AUTHOR]

The exciton properties of (Cd,Mn)Se-NrGO (nitrogen doped reduced graphene oxide) hybrid layered nanosheets have been studied in a magnetic field up to 10 T and compared to those of (Cd,Mn)Se nanosheets. The temperature dependent photoluminescence reveals the hybridization of inter-band exciton and intra-center Mn transition with enhancement of the binding energy of exciton-Mn hybridized state (80 meV with respect to 60 meV in (Cd,Mn)Se nanosheets) and increase of exciton—phonon coupling strength to 90 meV (with respect to 55 meV in (Cd,Mn)Se nanosheets). The circularly polarized magneto—photoluminescence at 2 K provides evidence for magnetic field induced exciton spin polarization and the realization of excitonic giant Zeeman splitting with geff as high as 165.4 ± 10.3, much larger than in the case of (Cd,Mn)Se nanosheets (63.9 ± 6.6), promising for implementation in spin active semiconductor devices. [ABSTRACT FROM AUTHOR]

We describe the creation and characterisation of a velocity tunable, spin-polarized beam of slow metastable argon atoms. We show that the beam velocity can be determined with a precision below 1% using matter-wave interferometry. The profile of the interference pattern was also used to determine the velocity spread of the beam, as well as the Van der Waals (VdW) co-efficient for the interaction between the metastable atoms and the multi-slit silicon nitride grating. The VdW co-efficient was determined to be C3 = 1.84 ± 0.17 a.u., in good agreement with values derived from spectroscopic data. Finally, the spin polarization of the beam produced during acceleration of the beam was also measured, demonstrating a spatially uniform spin polarization of 96% in the m = +2 state. [ABSTRACT FROM AUTHOR]

The persistent spin helix (PSH) system is considered to have promising applications in energy-conservation spintronics because it supports an extraordinarily long spin lifetime of carriers. Here, we predict that the existence of PSH state in two-dimensional (2D) ferroelectric NbOI2 monolayers. Our first-principles calculation results show that there exists Dresselhaus-type spin-orbit coupling (SOC) band splitting near the conduction-band minimum (CBM) of the NbOI2 monolayer. It is revealed that the spin splitting near CBM merely refers to out-of-plane spin configuration in the wave vector space, which gives rise to a long-lived PSH state that can be controlled by reversible ferroelectric polarization. We believe that the coupling characteristics of ferroelectric polarization and spin texture in NbOI2 provide a platform for the realization of fully electric controlled spintronic devices. [ABSTRACT FROM AUTHOR]

We investigate the effect of density down-ramps on the acceleration of ions via magnetic vortex acceleration in a near-critical density gas target by means of particle-in-cell simulations. The spin-polarization of the accelerated protons is robust for a variety of ramp lengths at around 80%. Significant increase of the ramp length is accompanied by collimation of low-polarization protons into the final beam and large transverse spread of the highly polarized protons with respect to the direction of laser propagation. [ABSTRACT FROM AUTHOR]

The spin effect of electrons/positrons (e−/e+) and polarization effect of γ photons are investigated in the interaction of two counter-propagating linearly polarized laser pulses of peak intensity 8.9 × 1023 W cm−2 with a thin foil target. The processes of nonlinear Compton scattering and nonlinear Breit–Wheeler pair production based on the spin- and polarization-resolved probabilities are implemented into the particle-in-cell (PIC) algorithm by Monte Carlo methods. It is found from PIC simulations that the average degree of linear polarization of emitted γ photons can exceed 50%. This polarization effect leads to a reduced positron yield by about 10%. At some medium positron energies, the reduction can reach 20%. Furthermore, we also observe that the local spin polarization of e−/e+ leads to a slight decrease of the positron yield about 2% and some anomalous phenomena about the positron spectrum and photon polarization at the high-energy range, due to spin-dependent photon emissions. Our results indicate that spin and polarization effects should be considered in calculating the pair production and laser-plasma interaction with the laser power of 10 PW to 100 PW classes. [ABSTRACT FROM AUTHOR]

We propose a correction to the coefficient of nuclear spin diffusion by a factor , where is the average nuclear spin polarization. The correction, derived by extending the Lowe–Gade theory to low-temperature cases, implies that transportation of nuclear magnetization through nuclear spin diffusion accelerates when the system is hyperpolarized, whereas for low polarization the correction factor approaches unity and the diffusion coefficient coincides with the conventional diffusion coefficient valid in the high-temperature limit. The proposed scaling of the nuclear spin diffusion coefficient can lead to observable effects in the buildup of nuclear polarization by dynamic nuclear polarization. [ABSTRACT FROM AUTHOR]

We introduce a generalized Rashba coupling approximation to analytically solve confined two-dimensional electron systems with both the Rashba and Dresselhaus spin–orbit couplings in an external magnetic field. A solvable Hamiltonian is obtained by performing a simple change of basis, which has the same form as that with only Rashba coupling. Each Landau state becomes a new displaced-Fock state instead of the original Harmonic oscillator Fock state. Analytical energies are consistent with the numerical ones in a wide range of coupling strength even for a strong Zeeman splitting, exhibiting the validity of the analytical approximation. By using the eigenstates, spin polarization correctly displays a jump at the energy-level crossing point, where the corresponding spin conductance exhibits a pronounced resonant peak. As the component of the Dresselhaus coupling increases, the resonant point shifts to a smaller value of the magnetic field. In contrast to pure Rashba couplings, we find that the Dresselhaus coupling and Zeeman splittings tend to suppress the resonant spin Hall effect. Our method provides an easy-to-implement analytical treatment to two-dimensional electron gas systems with both types of spin–orbit couplings by applying a magnetic field. [ABSTRACT FROM AUTHOR]

Electronic structure calculations of 4H-SiC doped with various transition metals reveal dilute magnetic semiconductor behavior in a material suitable for high-power and high-frequency semiconductor devices. Our results are consistent with prior work on V, Cr, and Mn doping and explore additional metals: Fe, Co, and Ni. Charge-state calculations show that the latter maintain amphoteric semi-insulating properties while offering a non-zero stable spin polarization and also greater asymmetry in the spin density of states than previously studied dopants. This indicates possible enhanced half-metal properties. Our results are consistent with crystal field theory, which helps interpret the observed spin states and assess the degree of charge localization and, subsequently, the range and strength of interactions relevant to ionization/capture and charge transport. These findings provide new avenues to tune the behavior of 4H-SiC for electronic device applications. [ABSTRACT FROM AUTHOR]

This paper investigates the spin characteristics of photoelectrons when hydrogen-like ions are centro-symmetrically irradiated with converging vector waves—a non-paraxial form of structured light. For a photon with given total angular momentum and third component thereof, photoelectrons with both helicities are obtained—in contrast to the fixed helicities produced by left- or right-circularly polarized light. The angular distribution of photoelectrons is broadly tunable through the radiation mode numbers, and opposite helicities can be extracted in synchronism.