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Light-induced spin polarization can be produced in chromophore-radical conjugates by reversible transitions between the excited trip-doublet and trip-quartet states. The precise origin of this polarization is often difficult to elucidate because different transition pathways, promoted by different interactions, can occur depending on the nature of the conjugate. Moreover, the complexity of the expressions describing the evolution of the spin state populations and polarization generated by these transitions makes it difficult to estimate the dependence of the polarization on factors such as the exchange interaction and spin–orbit coupling. Here, we present a theoretical analysis and show that by making assumptions for specific cases, simplified expressions can be obtained that provide better insight into the physical origins of the polarization. [ABSTRACT FROM AUTHOR]

Light-energy conversion processes causing alternations in spin multiplicity are attracting attention, but the development of quantum sensing technology applicable to fluid environment such as inside cells has been unexploited. How to achieve efficient energy conversion with controlling spin quantum coherence in a noisy condensed system is challenging. In this study, we investigate the effect of molecular motion on electron spin polarization to control quantum information of three-spin qubits in a fluid environment by using steric effects of organic molecules at room temperature. Using time-resolved electron paramagnetic resonance to observe light-induced generation and transfer of quantum entanglement, we directly observed a photoexcited quartet state generated in a radical-chromophore coupled system and clarified details of the electron spin polarization mechanism including a decoherence effect by activation of anisotropic molecular motion by the steric effects. [ABSTRACT FROM AUTHOR]

Chiral-induced-spin-selectivity of electron transport and its interplay with DNA's mechanical motion are explored in a double stranded DNA helix with spin–orbit-coupling. The mechanical degree of freedom is treated as a stochastic classical variable experiencing fluctuations and dissipation induced by the environment as well as force exerted by nonequilibrium, current-carrying electrons. Electronic degrees of freedom are described quantum mechanically using nonequilibrium Green's functions. Nonequilibrium Green's functions are computed along the trajectory for the classical variable taking into account dynamical, velocity dependent corrections. This mixed quantum-classical approach enables calculations of time-dependent spin-resolved currents. We showed that the electronic force may significantly modify the classical potential, which, at sufficient voltage, creates a bistable potential with a considerable effect on electronic transport. The DNA's mechanical motion has a profound effect on spin transport; it results in chiral-induced spin selectivity, increasing spin polarization of the current by 9% and also resulting in temperature-dependent current voltage characteristics. We demonstrate that the current noise measurement provides an accessible experimental means to monitor the emergence of mechanical instability in DNA motion. The spin resolved current noise also provides important dynamical information about the interplay between vibrational and spin degrees of freedom in DNA. [ABSTRACT FROM AUTHOR]

This study delves into the interplay of symmetry and structure in 2D systems to identify monolayers hosting valley physics together with the Rashba effect. Through high-throughput density functional theory calculations, 57 monolayers are identified exhibiting the Rashba effect, with the Rashba parameter α R spanning from 0 < α R < 2.0. The robustness of the Rashba parameters (α R) in these monolayers is primarily influenced by the physical parameters, highlighting the anti-crossing of Rashba-split bands and the Born effective charge (Z*). Among the 57 monolayers exhibiting the Rashba effect, the study identifies a subset of 23 monolayers presenting valley physics, demonstrating both in-plane and out-of-plane spin polarizations. The pronounced coupling of the valley and Rashba spin splitting is influenced by the in-plane and out-of-plane orbital contributions at the relevant K-points in the band spectra. In particular, the AB-type buckled structures feature these dual properties due to the presence of the broken inversion and mirror symmetries in them. Overall, the study eases the identification of monolayers with significant spin splitting and spin polarization, aiding in the design of high-performance 2D materials. [ABSTRACT FROM AUTHOR]

Chiral structures, breaking spatial inversion symmetry, exhibit non-zero chiroptical activity (COA) due to the coupling between their electric and magnetic responses under external electromagnetic fields, an effect absent in achiral systems. Non-magnetic chiral structures also exhibit Chiral-Induced Spin Selectivity (CISS), primarily detected in two terminal measurements in the linear regime, where spin selection emerges without external magnetic influence. Despite the different origins of these physical phenomena, our model captures the relevant physics required to address CISS as an intrinsic molecular effect with the basic ingredients: (i) chirality/inversion asymmetry, (ii) meV atomic spin–orbit coupling, and (iii) decoherence as a source of reciprocity breaking. In this work, we derived how the electronic system couples with polarized electromagnetic radiation to yield a spin-dependent polarization rotation power, quantified through the Rosenfeld tensor, predicting characteristic spin signatures in the COA. The model also predicts that a net spin polarization manifests in the molecular terminations that have been surmised as an explanation for chiral species separation of racemic mixtures and interactions with surface magnetic domains. A recent sensitive spectroscopic measurement of electron transfer in donor–acceptor complexes is consistent with the standalone CISS effect. [ABSTRACT FROM AUTHOR]

This study reports light narrowing in paraffin-coated vapor cells from room temperature 27 to 59 °C, where spin-exchange relaxation is suppressed. By means of a coating lock and eliminating the reservoir effect, an ultra-narrow magnetic resonance linewidth of 0.36 Hz and an atomic coherence lifetime of T 2 = 0.9 s are achieved. In cells free of buffer gas, the narrow linewidth over this broad temperature range is a result of enhanced spin polarization, which is facilitated by the effective suppression of radiation trapping benefiting from the stability of the vapor density. Using such cells in atomic magnetometers, the photon shot noise limit is estimated as 0.2 fT / Hz 1 / 2 and the spin-projection noise limit is estimated as 1.1 fT / Hz 1 / 2 . Also, a magnetometer system with the stable coated cell is identified, which demonstrates the potential for achieving relatively stable magnetometer sensitivity without precisely controlling the cell temperature. The long coherence lifetime and the broad operating temperature range expand the potential applications of quantum memory and other quantum sensors such as atomic clocks. [ABSTRACT FROM AUTHOR]

The second-order nonlinear Hall effect in 8-Pmmn monolayer borophene under the influence of an out-of-plane electric field and intrinsic spin–orbit interaction is reported. This unconventional response sensitive to the breaking of discrete and crystal symmetries can be tuned by the applied electric field, which can vary the bandgap induced by spin–orbit coupling. It is described by a Hall conductivity tensor that depends quadratically on the applied electric field. We find that the nonlinear Hall effect strongly depends on the spin polarization. In particular, it exhibits out of the phase character for spin-up and spin-down states. Remarkably, it undergoes a phase flip in the spin-up state at a large out-of-plane electric field that generates a staggered sublattice potential greater than the spin–orbit interaction strength. It is shown that the nonlinear Hall effect in the system originates from the broken inversion symmetry that plays an indispensable role in developing finite Berry curvature and its relevant dipole moment. It is found that at zero temperature, the nonlinear Hall response is maximal when the Fermi energy is twice the bandgap parameter and vanishes at large Fermi energies. Notably, the peak of nonlinear Hall response shifts to lower Fermi energies at finite temperature. [ABSTRACT FROM AUTHOR]

We have observed a transition from single to double hysteresis of nuclear spin polarization (NSP) with increasing magnetic field in a single InAlAs self-assembled quantum dot, which means the birth of a third stable branch that depends on the field strength. This NSP transition behavior could not be reproduced by standard model calculations using a fixed electron–nuclear spin correlation time τ c under different external field conditions. By introducing the field dependence of τ c , we were able to successfully reproduce the observed NSP transition. This finding on the phenomenological description of the magnetic field dependence will be a future highlight of τ c . [ABSTRACT FROM AUTHOR]

High-performance and stable spintronic devices have garnered considerable attention in recent years. Based on first-principle and Monte Carlo calculations, we demonstrate that under reasonable carrier doping, H-VSe2 exhibits 100% spin polarization, a magnetic anisotropy energy of 581 μeV, a tunable easy-axis, and a Curie temperature of 330 K. Moreover, Dzyaloshinskii–Moriya interactions in H-VSe2 and magnetic hysteresis loops are determined theoretically for the first time, which provides more precise and comprehensive descriptions of its magnetic properties under finite temperatures and external magnetic field. This work suggests that H-VSe2 is a powerful candidate for spintronic devices, and it provides solid theoretical support for future experiments. [ABSTRACT FROM AUTHOR]

The interactions between the electronic magnetic moment and the nuclear spin moment, i.e., magnetic hyperfine (HF) interactions, play an important role in understanding electronic properties of magnetic systems and in realizing platforms for quantum information science applications. We investigate the HF interactions for atomic systems and small molecules, including Ti or Mn, by using Fermi–Löwdin orbital (FLO) based self-interaction corrected (SIC) density-functional theory. We calculate the Fermi contact (FC) and spin-dipole terms for the systems within the local density approximation (LDA) in the FLO-SIC method and compare them with the corresponding values without SIC within the LDA and generalized-gradient approximation (GGA), as well as experimental data. For the moderately heavy atomic systems (atomic number Z ≤ 25), we find that the mean absolute error of the FLO-SIC FC term is about 27 MHz (percentage error is 6.4%), while that of the LDA and GGA results is almost double that. Therefore, in this case, the FLO-SIC results are in better agreement with the experimental data. For the non-transition-metal molecules, the FLO-SIC FC term has the mean absolute error of 68 MHz, which is comparable to both the LDA and GGA results without SIC. For the seven transition-metal-based molecules, the FLO-SIC mean absolute error is 59 MHz, whereas the corresponding LDA and GGA errors are 101 and 82 MHz, respectively. Therefore, for the transition-metal-based molecules, the FLO-SIC FC term agrees better with experiment than the LDA and GGA results. We observe that the FC term from the FLO-SIC calculation is not necessarily larger than that from the LDA or GGA for all the considered systems due to the core spin polarization, in contrast to the expectation that SIC would increase the spin density near atomic nuclei, leading to larger FC terms. [ABSTRACT FROM AUTHOR]

Magnetic materials with high negative spin polarization have been sought as a building block to increase the design freedom and performance of spintronics devices. In this paper, we investigate negative spin polarization of Mn2VGa Heusler alloy in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices. We fabricated an epitaxial CPP-GMR stack consisting of Mn2VGa/Ag/CoFe with L21 ordering in the Mn2VGa layer and observed negative magnetoresistance (MR), which provided evidence of negative spin polarization. The MR ratio depended on thermal treatments (deposition at an elevated temperature and post-annealing), because these processes affected the ordering, roughness, and magnetic properties of Mn2VGa. The maximum MR ratio reached −1.8% at room temperature and −3.0% at low temperatures, representing the highest among the negative MR values in pseudo-spin-valve CPP-GMR devices despite the underestimation due to an incomplete antiparallel magnetization configuration. These findings demonstrate the potential of Mn2VGa for a material with high negative spin polarization. [ABSTRACT FROM AUTHOR]

Understanding the electronic transport properties of low-dimensional devices has increased dramatically in recent decades, especially for those with a promising future for application in nanotechnology. Among these nanoscopic systems are molecular systems, particularly organic molecules such as catechol, representing the small piece of a potential conductor assembled through larger biomolecules and inserted between two or more metal contacts. In this work, we present a theoretical description of the electronic transport of catechol, based on its π -conjugated aromatic system, under an external magnetic field stimulus, which is transverse to the alignment of the molecule. Thus, we analyze catechol's spintronic properties through the magnetoresistance generated by this field. We model the molecule using a tight-binding Hamiltonian and Green's functions; the transmission probability is calculated by means of the Fisher-Lee relation, and the characteristic current–voltage, spin polarization, and magnetoresistance curves based on Landauer's approach for two linking models of catechol to the metallic contacts. The results suggest a strong dependence on the spin direction of the charge carriers and the Zeeman energy (E z) on the Fermi level, generating a switch-like mechanism going from conducting to semiconducting material. This behavior opens a potential application of these catechol-based systems in future spintronic devices. [ABSTRACT FROM AUTHOR]

We theoretically study the magnetic phase transition of condensed exciton-polariton microcavities in an applied magnetic field. When the magnetic field is strong, all polariton spins are polarized parallel to the magnetic field as usual. On the contrary, in the weak magnetic-field region, the polariton polarization degree is negative, namely, anti-parallel to the magnetic field. For a strong magnetic field, the magnetic phase of the polaritons arises and leads to a paramagnetic, while around a weak magnetic field, with zero exciton–photon detunings, and weak Rabi splitting the spin polarization of the polaritons leads to a diamagnetic. Thus, magneto-polariton phase transition polarization originates from the competition between the polariton Zeeman effect and polariton–polariton interactions. Moreover, the polariton polarization strongly depends on the exciton–photon detuning and Rabi splitting and has a large negative value as they are both small. At last, we compare our theoretical results with the experiments and find they match each other very well. [ABSTRACT FROM AUTHOR]

Chiral molecules can exhibit strong spin–orbit coupling, which can result in a large spin polarization. This is due to the fact that the energy levels of the electrons in a chiral molecule are strongly influenced by the chiral structure of the molecule, which can result in the separation of the energy levels for electrons with different spin orientations. We report a controlled spin-selective transmission of electrons through 20 base-paired poly-cytosine molecules functionalized with MoS2 flakes on ITO glass via the quantum mechanical tunneling effect. A reversion in spin polarization was observed after the silver ions interact with poly-cytosine due to the strong coordination of Ag(I) with cytosine–cytosine (C–C) mismatches, indicating the formation of duplex structural motifs, as confirmed by the circular dichroism spectroscopy at room temperature. Manipulating the spin of an electron through such a small molecule merely controlled by special cations could pave the way for major advances in spin-independent charge transport, advanced bioanalytical system design, and related applications. [ABSTRACT FROM AUTHOR]

Chiral molecules can exhibit strong spin–orbit coupling, which can result in a large spin polarization. This is due to the fact that the energy levels of the electrons in a chiral molecule are strongly influenced by the chiral structure of the molecule, which can result in the separation of the energy levels for electrons with different spin orientations. We report a controlled spin-selective transmission of electrons through 20 base-paired poly-cytosine molecules functionalized with MoS2 flakes on ITO glass via the quantum mechanical tunneling effect. A reversion in spin polarization was observed after the silver ions interact with poly-cytosine due to the strong coordination of Ag(I) with cytosine–cytosine (C–C) mismatches, indicating the formation of duplex structural motifs, as confirmed by the circular dichroism spectroscopy at room temperature. Manipulating the spin of an electron through such a small molecule merely controlled by special cations could pave the way for major advances in spin-independent charge transport, advanced bioanalytical system design, and related applications. [ABSTRACT FROM AUTHOR]

We offer a brief overview of the present status of ultrafast helicity-independent all-optical magnetization switching (HI-AOS) phenomena in ferromagnet (FM) films and multilayers. The discovery of HI-AOS in ferrimagnet alloys dates back to 2011. From an application standpoint, utilizing HI-AOS in an FM brings about several benefits. One of these advantages is its enhanced spin polarization, which leads to a higher tunneling magneto-resistance (TMR) across a magnetic tunnel junction device. The enhanced TMR greatly enhances its reading capability. Time-resolved and single-shot magneto-optical Kerr effect measurement has successfully enabled the detection of magnetization switching. The magnetization reversal speed stays within the range of tens of picoseconds. There are two methods to achieve HI-AOS in an FM: (1) ultrafast spin-current-induced magnetization switching, and (2) ultrafast exchange interaction-dominated magnetization switching. We conduct a comprehensive analysis of a selection of recent academic publications that delve into both of these subjects and offer a succinct assessment of the present status of the ultrafast HI-AOS phenomenon in FMs. Finally, we discuss the latest developments in tackling the obstacles the HI-AOS mechanism faces and the exciting prospects for developing a high-speed spintronic memory device. [ABSTRACT FROM AUTHOR]

The pursuit of miniaturized, high-performance electronic devices has intensified research into novel materials with extraordinary properties. While semiconductors lead the way in optoelectronics and energy harvesting, the burgeoning field of spintronics utilizing electron charge and spin promises revolutionary advances in information processing and storage. A critical component of spintronics is identifying materials with half-metallic behavior, characterized by complete spin polarization at the Fermi level. This study explores chromium (Cr)-doped CaTe as a candidate for half-metallic behavior. Using advanced computational techniques, we investigate the impact of Cr doping on the electronic and magnetic properties of CaTe. Our findings reveal that Cr-doped CaTe exhibits significant crystal field splitting and exchange splitting energies, leading to robust magnetic properties and half-metallic behavior across varying doping concentrations. Notably, the Curie temperature of Cr-doped CaTe exceeds room temperature starting from a 14% Cr concentration, highlighting its practical viability for spintronic applications. The results underscore the potential of Cr-doped CaTe for integration into spintronic devices, offering insights into the electronic structure and magnetic interactions essential for developing next-generation spintronic technologies. [ABSTRACT FROM AUTHOR]

Electromagnetic neutrino properties can be a manifestation of new physics. We study electromagnetic contribution to elastic neutrino–nucleon scattering processes. Following our approach developed for the case of elastic neutrino–electron and neutrino–proton collisions, in our formalism we account for possible electromagnetic form factors of massive neutrinos: the charge, magnetic, electric and anapole form factors of both diagonal and transition types. Considering Dirac neutrinos from an astrophysical source arriving at a detector on Earth, we assume them to have arbitrary spin polarization due to effects of neutrino spin oscillations induced by neutrino magnetic moment interactions with magnetic fields both in the astrophysical source and in the interstellar environment. When treating the nucleon electromagnetic vertex, we take into account not only charge and magnetic form factors of a nucleon, but also its electric and anapole form factors. We numerically examine how the effects of electromagnetic properties and spin polarization of the cosmic neutrinos can influence the differential cross sections of their elastic scattering on nucleons in the detector. [ABSTRACT FROM AUTHOR]

Severe photogenerated charge carrier recombination involved in photocatalytic CO2 reduction leads to low photocatalytic efficiency. Here we demonstrate that a chiral hierarchical structure could facilitate charge separation in BiOBr, thus suppressing charge recombination and enhancing photocatalytic performance. Chiral helical flower-like BiOBr nanospheres were prepared via a D / L -sorbitol-assisted hydrothermal process, exhibiting a 1.1-fold increase in photocatalytic CO2 reduction activity compared to the achiral counterparts. This enhancement is attributed to the chiral-induced electron spin polarization regulation, as confirmed by photoluminescence and electrochemical characterizations. This work opens an alternative avenue for the design of high-performance photocatalysts. [ABSTRACT FROM AUTHOR]

Spin-orbit torque (SOT) provides a promising mechanism for electrically encoding information in magnetic states. Unlike existing schemes, where the SOT is passively determined by the material and device structures, an active manipulation of the intrinsic SOT polarity would allow for flexibly programmable SOT devices. Achieving this requires electrical control of the current-induced spin polarization of the spin source. Here we demonstrate a proof-of-concept current-programmed SOT device. Using a noncollinear-antiferromagnetic/nonmagnetic/ferromagnetic Mn3Sn/Mo/CoFeB heterostructure at zero magnetic field, we show current-induced switching in the CoFeB layer due to the spin current polarized by the magnetic structure of the Mn3Sn; by properly tuning the driving current, the spin current from the CoFeB further reverses the magnetic orientation of the Mn3Sn, which determines the polarity of the subsequent switching of the CoFeB. This scheme of mutual switching can be achieved in a spin-valve-like simple protocol because each magnetic layer serves as a reversible spin source and target magnetic electrode. It yields intriguing proof-of-concept functionalities for unconventional logic and neuromorphic computing. Spin-orbit torque can drive switching in ferromagnets, and therefore can be used for the electrical writing of magnetic bits. Here, Yoon et al. take this essential idea a step further, demonstrating mutual switching, where a ferromagnet can drive switching in an antiferromagnet, switching the sign of the spin-orbit torque itself. [ABSTRACT FROM AUTHOR]

In this manuscript we study the magnetic MAOX phases (M = Mn, Cr; A = Ga, Al, X = C) obtained by the replacement of the A-layer in the parent MAX phase by the AO2 layer. The screening analysis of the magnetic and electronic properties of Mn- and Cr-based MAOX phases is performed using DFT calculations. All MAOX are thermodynamically stable. It was found that in MAOX phases Cr magnetic moments are pronounced increased in compare to corresponding MAX phase. Moreover, drastically changes in the electronic structure arise in Cr2AlO2C and Cr2GaO2C MAOX phases. The metal behavior in Cr2GaC MAX phase changes for the near to half-metallic behavior with 90% spin polarization at the Fermi energy in Cr2GaO2C MAOX phases. We have found that in Cr2AlO2C, the change in the electronic structure leads to the formation of the spin-gapless semiconductor state under slight extension in the ab plane. The obtained results make Cr2GaO2C and especially Cr2AlO2C prospective candidates for application as functional elements of electronics and spintronics. [ABSTRACT FROM AUTHOR]

Redox-induced magnetic regulation in organic diradicals is distinctly attractive. In this work, taking nitroxide radicals as spin sources, we predict the magnetic properties of 9, 10-anthraquinone, 9, 10-phenaquone, 9, 10-diazanthracene and 9, 10-diazepine-bridged molecular diradical structures in which the couplers are prone to dihydrogenation reduction at positions 9 and 10. As evidenced at both the B3LYP and M06-2X levels of theory, the calculations confirm that the magnetic transitions between ferromagnetism and antiferromagnetism can take place for 9, 10-anthraquinone and 9, 10-diazanthracene-bridged diradicals after dihydrogenation. The differences in the magnetic behaviors and magnetic magnitudes of 9, 10-anthraquinone and 9, 10-diazanthracene-bridged diradicals before and after dihydrogenation could be attributed to their noticeably different spin-interacting pathways. As for 9, 10-phenaquone and 9, 10-diazepine-bridged diradicals, the calculated results indicate that the signs of their magnetic exchange coupling constants J do not change, but the magnitudes remarkably change after dihydrogenation. The connecting bond character and spin polarization are crucial in explaining the different magnetic magnitudes of these designed diradicals. In detail, shorter bonds and larger spin polarization are responsible for strong magnetic coupling. In addition, the diradical with an extensively π-conjugated structure can effectively promote magnetic coupling. The McConnell's spin alternation rule is the key to understanding the observed ferromagnetism and antiferromagnetism of these diradicals. The work provides useful information for the rational design of redox-regulated magnetic molecular switches. [ABSTRACT FROM AUTHOR]

Magnetic field effects (MFE) of ferromagnetic spin electrocatalysts have attracted significant attention due to their potential to enhance catalytic activity under an external magnetic field. However, no ferromagnetic spin catalysts have demonstrated MFE in the electrocatalytic reduction of nitrate for ammonia (NO3RR), a pioneering approach towards NH3 production involving the conversion from diamagnetic NO3− to paramagnetic NO. Here, we report the ferromagnetic Fe-TiO2 to investigate MFE on NO3RR. Fe-TiO2 possesses a high density of atomically dispersed Fe sites and exhibits an intermediate-spin state, resulting in magnetic ordering through ferromagnetism. Assisted by a magnetic field, Fe-TiO2 achieves a Faradaic efficiency (FE) of up to 97% and an NH3 yield of 24.69 mg mgcat−1 at −0.5 V versus reversible hydrogen electrode. Compared to conditions without an external magnetic field, the FE and NH3 yield for Fe-TiO2 under an external magnetic field is increased by ~21.8% and ~ 3.1 times, respectively. In-situ characterization and theoretical calculations show that spin polarization enhances the critical step of NO hydrogenation to NOH by optimizing electron transfer pathways between Fe and NO, significantly boosting NO3RR activity. The magnetic field effect of ferromagnetic spin electrocatalysts to enhance catalytic activity under external magnetic fields brings promises and challenges. Here, the authors report the ferromagnetic Fe-TiO2 to investigate magnetic field effect on electrocatalytic reduction of nitrate for ammonia. [ABSTRACT FROM AUTHOR]

The ultimate goal of catalysis is to control the cleavage and formation of chemical bonds at the molecular or even atomic level, enabling the customization of catalytic products. The essence of chemical bonding is the electromagnetic interaction between atoms, which makes it possible to directly manipulate the dynamic behavior of molecules and electrons in catalytic processes using external electric, magnetic and electromagnetic fields. In this tutorial review, we first introduce the feasibility and importance of field effects in regulating catalytic reaction processes and then outline the basic principles of electric-/magnetic-/electromagnetic-field interaction with matter, respectively. In each section, we further summarize the relevant important advances from two complementary perspectives: the macroscopic molecular motion (including translation, vibration and rotation) and the microscopic intramolecular electron state alteration (including spin polarization, transfer or excitation, and density of states redistribution). Finally, we discuss the challenges and opportunities for further development of catalysis under electric-/magnetic-/electromagnetic-field coupling. [ABSTRACT FROM AUTHOR]

Interactions of chiral light with chiral matter, such as Raman optical activity (ROA) and, independently, spin-polarized materials have attracted a lot of interest for both fundamental science and applications. The ROA, on the one hand, provides information on chiral phonons of molecules. However, the short-lifetime ROA signal in general is extremely weak and requires long exposure times, making it not accessible for many important systems with short lifetime. Materials exhibiting high spin polarization in d or f band, on the other hand, remain very limited even at very low temperature. There has been no report on materials exhibiting spin polarization in s band. Herewith, we report a room temperature, full spin polarization in unconventional, correlated s band of highly oriented single-crystalline gold quantum-dots (HOSG-QDs). Intriguingly, the HOSG-QDs produce a chiral correlated-plasmons enhanced Raman optical activity (CP-ROA) with anomalous ROA enhancement and strong spin-dependent chiral coupling. We then address a fundamental problem in crystal violet. Using spin-polarized HOSG-QDs chips, we observe strong CP-ROA signal, revealing chiral properties. The chiral correlated-plasmons of HOSG-QDs interact with the spin, electronic, and lattice structures of crystal violet, revealing chiral phonons and chiral electronic Raman excitations of crystal violet. Such a strong CP-ROA spectrum is obtained within a minute of measurement and a simple preparation without patterning. Our result shows that the CP-ROA based on a spin-polarized HOSG-QDs is extremely sensitive to the chiral property of phonon and spin and electronic structures and a fast, label-free chiral spectroscopic-based detection. [ABSTRACT FROM AUTHOR]

In this paper, we review our work on the manipulation of magnetization in ferromagnetic semiconductors (FMSs) using electric-current-induced spin-orbit torque (SOT). Our review focuses on FMS layers from the (Ga,Mn)As zinc-blende family grown by molecular beam epitaxy. We describe the processes used to obtain spin polarization of the current that is required to achieve SOT, and we briefly discuss methods of specimen preparation and of measuring the state of magnetization. Using specific examples, we then discuss experiments for switching the magnetization in FMS layers with either out-of-plane or in-plane easy axes. We compare the efficiency of SOT manipulation in single-layer FMS structures to that observed in heavy-metal/ferromagnet bilayers that are commonly used in magnetization switching by SOT. We then provide examples of prototype devices made possible by manipulation of magnetization by SOT in FMSs, such as read-write devices. Finally, based on our experimental results, we discuss future directions which need to be explored to achieve practical magnetic memories and related applications based on SOT switching. [ABSTRACT FROM AUTHOR]

We use Density Functional Theory and Monte Carlo simulation to investigate the structural, electronic, and magnetic properties of the ferromagnetic inverse Heusler alloys Fe2RhSi and Fe2RhGe. The metallic nature of both alloys is confirmed using GGA, GGA+U, and meta-GGA methods. The calculated magnetic moments are 5.017μB for Fe2RhSi and 5.177μB for Fe2RhGe, aligning well with experimental findings. Spin polarization calculations yield 70% for Fe2RhSi and 53.03% for Fe2RhGe using the GGA method, while other methods produce values below 30%. Additionally, GGA+U calculations indicate a martensite transition at approximately c∕a=1.08 for both alloys without affecting their magnetic state. The Curie temperatures are around 900K for Fe2RhGe and Fe2RhSi, which closely match experimental data. The high spin polarization and Curie temperature make Fe2RhSi a promising candidate for spintronic applications. [ABSTRACT FROM AUTHOR]

Here, based on first-principles calculations and topological analysis, we show that the spin-polarized topological phase is present in a van der Waals (vdW) heterostructure WSe2/CrI3. We reveal that magnetism induced by proximity effects in the heterostructure breaks the time-reversal symmetry (TRS) and thus induces gapped topological edge states, exhibiting the TRS-breaking quantum spin Hall (QSH) effect. By applying a stress field, the WSe2/CrI3 heterostructure manifests enhanced spin polarization, Rashba splitting, and tunable bandgap. The TRS-breaking QSH effect observed in the WSe2/CrI3 heterostructure exhibits remarkable robustness against interlayer shearing. The distinct anisotropy associated with in-plane strain provides precise manipulation strategies for bandgap engineering. Notably, in-plane tensile strain can significantly increase the nontrivial bandgap by up to 98 meV, suggesting the magnetic WSe2/CrI3 heterostructure represents an outstanding platform for achieving the TRS-breaking QSH effect at room temperature. Our findings provide a theoretical foundation for the development of low-dissipation spintronic nanodevices. [ABSTRACT FROM AUTHOR]

We demonstrate a significant effect of atomic-scale MgO insertion layers on the tunnel magnetoresistance (TMR) in epitaxial magnetic tunnel junctions (MTJs) using a small bandgap oxide MgGa2O4. An enhanced TMR ratio of 151% at room temperature (resistance area product, RA: 23 kΩ ⋅ μm2) and 291% at 5 K (RA: 26 kΩ ⋅ μm2) were observed using 0.3 nm MgO insertion layers at the bottom and top barrier interfaces in Fe/MgGa2O4/Fe(001) MTJs with a total barrier thickness of 2.3 nm. The TMR showed a strong MgO thickness dependence. Microstructure analyses revealed that after MgO insertion, a homogeneous rock-salt structured Mg0.55Ga0.45O(001) barrier is formed, which differs from the nominal spinel crystal MgGa2O4. Elemental mapping of the MTJ showed that Ga diffusion into the adjacent Fe can be effectively suppressed while maintaining perfect lattice-matching at the Fe/barrier interfaces, thereby improving effective tunneling spin polarization through the barrier. The RA of the Mg0.55Ga0.45O (2.3 nm) MTJ is smaller than that of a comparable MgAl2O4 barrier (2.3 nm), thanks to the lower barrier height of the Mg0.55Ga0.45O as confirmed by the current–voltage characteristics. [ABSTRACT FROM AUTHOR]

The electrical spin injection and detection in perpendicularly magnetized Mn/Co/n-GaAs junction was investigated using a non-local method. Clear non-local spin-valve signals and Hanle effect signals were observed at 77 K, providing direct evidence of the injection and detection of perpendicularly polarized spins through all electrical methods. The magnitude of the spin-valve signal was one order of magnitude smaller than that observed in a reference sample with an in-plane magnetized CoFe due to the low spin polarization of the ultrathin Mn/Co electrodes. It was found that the spin polarization at the interface between Mn/Co electrode and n+-GaAs had a relatively weak bias-current dependence in contrast to that at CoFe/n+-GaAs interface. The estimated spin lifetime of perpendicular spins injected from the Mn/Co bilayer into n-GaAs was approximately 1.9 ns at 77 K. This value is similar to that of in-plane spins injected from CoFe, indicating that the spin lifetime was not strongly dependent on the spin orientation in the bulk GaAs channel. [ABSTRACT FROM AUTHOR]

Superconducting spintronics explores the interplay between superconductivity and magnetism, sparking substantial interest in nonunitary superconductors as a platform for magneto-superconducting phenomena. However, identifying nonunitary superconductors remains challenging. We demonstrate that spin current driven by thermal gradients sensitively probes the nature of the condensate in nonunitary superconductors. Spin polarization of the condensate in momentum space induces the superconducting spin Seebeck effect, where a spin current is generated along thermal gradients without a thermoelectric charge current. Notably, the nonvanishing superconducting spin Seebeck effect provides a smoking gun evidence of nonunitary superconductivity because it reflects the spin polarization of the condensate in momentum space, irrespective of whether the net pair spin magnetization vanishes. At the same time, the spin chirality of the condensate induces the spin Nernst effect, where a spin current is generated perpendicular to thermal gradients in nonunitary superconductors. These spin caloritronic phenomena offer a definitive probe of nonunitary superconductors. [ABSTRACT FROM AUTHOR]

Most Rashba spin splitting experimentally studied so far has ideal lattice with inversion symmetry broken, which limits the possibility to minimize the presence of spin-degenerate carriers near the Fermi level. Here, we report a novel 2D Au2Sb surface alloy decorated with periodic structural defects that exhibits modulation on the Rashba spin-orbit coupling band. Spin- and angle-resolved photoemission spectroscopy reveals a Rashba spin-split band with antiparallel spin polarization, significantly broadened compared to the Au₂Sn surface alloy. From the good agreement between the experimental results and DFT calculations, we identify that the broadening of the Rashba bands comes from variations in Sb atom corrugation induced by the periodic three-pointed star-shaped defects. These periodic defects can shift the energy position of the Rashba bands without breaking the in-plane rotational and mirror symmetries. Our findings highlight the potential to tune spin-dependent properties in 2D materials for spintronic applications. [ABSTRACT FROM AUTHOR]

Using a first-principles approach, this study delves into the effects of strain and electrostatic doping on the electronic and magnetic properties of the GaN/VTe2 van der Waals (vdW) heterostructure. The results reveal that when the GaN/VTe2 vdW heterostructure is doped with 0.1 h /0.2 h of electrostatic charge, its magnetization direction undergoes a remarkable reversal, shifting from out-of-plane orientation to in-plane direction. Therefore, we conduct a thorough investigation into the influence of electron orbitals on magnetic anisotropy energy. In addition, as the strain changes from −1% to 1%, the 100% spin polarization region of the GaN/VTe2 vdW heterostructure becomes smaller. It is worth noting that at a doping concentration of 0.1 h, the GaN/VTe2 vdW heterostructure has a Curie temperature of 30 K above room temperature. This comprehensive study provides valuable insights and provides a reference for analyzing the electronic and magnetic properties of low-dimensional systems. [ABSTRACT FROM AUTHOR]

Spin and valley polarizations (Ps and PKK') and tunneling magnetoresistance (TMR) are demonstrated in the ferromagnetic/barrier/normal/barrier/ferromagnetic WSe2 junction, with the gate voltage and off-resonant circularly polarized light (CPL) applied to the two barrier regions. The minimum incident energy of non-zero spin- and valley-resolved conductance has been derived, which is consistent with numerical calculations and depends on the electric potential U, CPL intensity ΔΩ, exchange field h, and magnetization configuration: parallel (P) or antiparallel (AP). For the P (AP) configuration, the energy region with PKK' = -1 or Ps = 1 is wider (narrower) and increases with ΔΩ. As h increases, the Ps = 1 (PKK' = -1 or Ps = 1) plateau becomes wider (narrower) for the P (AP) configuration. As U increases, the energy region with PKK' = -1 increases first and then moves parallel to the EF-axis, and the energy region with Ps = 1 for the P configuration remains unchanged first and then decreases. The energy region for TMR = 1 increases rapidly with h, remains unchanged first and then decreases as U increases, and has little dependence on ΔΩ. When the helicity of the CPL reverses, the valley polarization will switch. This work sheds light on the design of spin-valley and TMR devices based on ferromagnetic WSe2 double-barrier junctions. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive theoretical investigation into the scattering of electrons and positrons from nitrogen dioxide (NO2) molecules across a broad energy ranging from 1 eV to 1 MeV. The focus of the analysis encompasses a variety of cross‐sections, including differential, integrated elastic, inelastic, total ionization, total, momentum transfer and viscosity. Additionally, the study explores the spin polarization effects within electron/positron‐NO2 scattering events. Utilizing a combination of relativistic Dirac partial wave analysis, the independent atom model (IAM), and the screening adjusted independent atom model (IAMS), this research achieves a refined understanding of scattering mechanisms. Comparative assessments with prior theoretical and empirical findings reveal that the IAM approach yields lesser accuracy at lower energies, while maintaining commendable agreement with existing data at medium to high energies. The insights and methodologies developed herein are anticipated to contribute significantly to the advancement of future research in this domain. [ABSTRACT FROM AUTHOR]