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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]

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]

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]

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]

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 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]

In connection to the chiral-induced spin selectivity effect, we theoretically analyze the electronic and spin states of edges of a finite p-orbital helical atomic chain with the intra-atomic spin–orbit interaction. This model can host the spin-filtering state in which two up-spins propagate in one direction and two down-spins propagate in the opposite direction without breaking the time-reversal symmetry (TRS). The enhancement of charge modulations concentrated at the edges due to the evanescent states is induced, although the spin density is absent because of the TRS. A Zeeman field at an edge of the atomic chain, which breaks the TRS, yields a finite spin polarization, whose direction depends on the chirality of the molecule. The chirality change induces a reasonable amount of the energy difference, which may provide an insight into the enantioselective adsorption of chiral molecules on the ferromagnetic surface. [ABSTRACT FROM AUTHOR]

Enantio-discrimination and spin-dependent electrochemistry (SDE), as a manifestation of the chirality-induced spin selectivity (CISS) effect, are important phenomena that can be probed by "chiral" electrochemistry. Here, we prepared chiralized surfaces of gold and nickel, to serve as working electrodes, through effective chemisorption of enantiopure dimethyl-bis(ethylenedithio)-tetrathiafulvalene (DM-BEDT-TTF) 1, tetramethyl-bis(ethylenedithio)-tetrathiafulvalene (TM-BEDT-TTF) 2, and their capped silver nanoparticle (AgNPs) aggregate by simple incubation of the metallic substrates. The effective chemisorption was checked by means of ultrahigh vacuum x-ray photoelectron spectroscopy (XPS) and by electro-desorption experiments, i.e., cyclic voltammetry (CV) scans showing a first electro-desorption peak at about −1.0 V. The Au|1 and Au|2 chiral electrodes were successfully used in CV experiments exploiting chiral redox probes. Finally, the hybrid interfaces Ni|enantiopure 1 or 2|AgNPs served as working electrodes in SDE experiments. In particular, the hybrid chiral interfaces Ni|(R)-2|AgNPs and Ni|(S)-2|AgNPs exhibited a significant spin-filtering ability, as a manifestation of the CISS effect, with average spin polarization values of 15%. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the spin transport properties of binuclear manganese phthalocyanine (M n 2 P c 2) spintronic devices sandwiched between two nickel electrodes using the non-equilibrium Green's function method in combination with density functional theory. Based on the calculation results, the M n 2 P c 2 device exhibited excellent spin-filtering capabilities, demonstrating an exceptionally high spin filter efficiency (SFE). Irrespective of the parallel or antiparallel orientation of magnetization in the electrodes, we observed that when both manganese atoms were in a spin-up state, the SFE of spin-resolved currents under finite bias and the thermoelectric currents induced by temperature gradients at fixed temperatures were both close to 100%. The large spin Seebeck polarization of the M n 2 P c 2 device was also obtained at low reference temperatures. This study explores the potential for developing multifunctional spintronic single-molecule devices using Ni − M n 2 P c 2. [ABSTRACT FROM AUTHOR]

We report on a strategy to indirectly read out the spectrum of an electronic spin via polarization transfer to nuclear spins in its local environment. The nuclear spins are far more abundant and have longer lifetimes, allowing for repeated polarization accumulation in them. Subsequent nuclear interrogation can reveal information about the electronic spectral density of states. We experimentally demonstrate the method by reading out the ESR spectrum of nitrogen vacancy center electrons in diamond via readout of lattice 13C nuclei. Spin-lock control on the 13C nuclei yields a significantly enhanced signal-to-noise ratio for the nuclear readout. Spectrally mapped readout presents operational advantages in being background-free and immune to crystal orientation and optical scattering. We harness these advantages to demonstrate applications in underwater magnetometry. The physical basis for the "one-to-many" spectral map is itself intriguing. To uncover its origin, we develop a theoretical model that maps the system dynamics, involving traversal of a cascaded structure of Landau–Zener anti-crossings, to the operation of a tilted "Galton board." This work points to new opportunities for "ESR-via-NMR" in dilute electronic systems and in hybrid electron–nuclear quantum memories and sensors. [ABSTRACT FROM AUTHOR]

Chiral molecules can act as spin filters, preferentially transmitting electrons with spins polarized along their direction of travel, an effect known as chirality-induced spin selectivity (CISS). In a typical experiment, injected electrons tunnel coherently through a layer of chiral material and emerge spin-polarized. It is also possible that spin polarization arises in radical pairs formed photochemically when electrons hop incoherently between donor and acceptor sites. Here we aim to identify the magnetic properties that would optimise the visibility of CISS polarization in time-resolved electron paramagnetic resonance (EPR) spectra of transient radical pairs without the need to orient or align their precursors. By simulating spectra of actual and model systems, we find that CISS contributions to the polarization should be most obvious when at least one of the radicals has small g-anisotropy and an inhomogeneous linewidth larger than the dipolar coupling of the two radicals. Under these conditions there is extensive cancellation of absorptive and emissive enhancements making the spectrum sensitive to small changes in the individual EPR line intensities. Although these cancellation effects are more pronounced at lower spectrometer frequencies, the spectral changes are easier to appreciate with the enhanced resolution afforded by high-frequency EPR. Consideration of published spectra of light-induced radical pairs in photosynthetic bacterial reaction centres reveals no significant CISS component in the polarization generated by the conventional spin-correlated radical pair mechanism. [ABSTRACT FROM AUTHOR]

We present computational results on electronic, magnetic, and structural properties of CoVMnSb, a quaternary Heusler alloy. Our calculations indicate that this material may crystallize in two energetically close structural phases: inverted and regular cubic. The inverted cubic phase is the ground state, with ferrimagnetic alignment, and around 80% spin polarization. Despite having a relatively large bandgap in the minority-spin channel close to the Fermi level, this phase does not undergo a half-metallic transition under pressure. This is explained by the "pinning" of the Fermi level at the minority-spin states at the Γ point. At the same time, the regular cubic phase is half-metallic and retains its perfect spin polarization under a wide range of mechanical strain. Transition to a regular cubic phase may be attained by applying uniform pressure (but not biaxial strain). In practice, this pressure may be realized by an atomic substitution of non-magnetic atoms (Sb) with another non-magnetic atom (Si) of a smaller radius. Our calculations indicate that 25% substitution of Sb with Si results in a half-metallic regular cubic phase being the ground state. In addition, CoVMnSb0.5Si0.5 retains its half-metallic properties under a considerable range of mechanical pressure, as well as exhibits thermodynamic stability, thus making this alloy attractive for potential spintronic applications. We hope that the presented results will stimulate experimental efforts to synthesize this compound. [ABSTRACT FROM AUTHOR]

The article discusses the chiral induced spin selectivity effect (CISS), which is the finding that the motion of an electron within or through chiral systems depends on the spin of that electron. The article explains that while the effect has been observed experimentally, developing a quantitative theoretical description has been challenging. The article also highlights the different types of experimental measurements that have been used to study CISS, including measurements of spin-dependent transmission, tunneling currents, magnetization, and magnetic domains. The article concludes by discussing the potential applications of CISS in spintronics, electrochemistry, and biology, and expresses optimism that further research will reveal the mechanism behind the CISS effect. [Extracted from the article]

Mastering the manipulation of the electron spin plays a crucial role in comprehending the behavior of organic materials in several applications, such as asymmetric catalysis, chiroptical switches, and electronic devices. A promising avenue for achieving such precise control lies in the Chiral Induced Spin Selectivity (CISS) effect, where electrons with a favored spin exhibit preferential transport through chiral assemblies of specific handedness. Chiral supramolecular polymers emerge as excellent candidates for exploring the CISS effect due to their ability to modulate their helical structure through noncovalent interactions. In this context, systems capable of responding to external stimuli are particularly intriguing, sometimes even displaying chirality inversion. This study unveils spin selectivity in chiral supramolecular polymers, derived from single enantiomers, through scanning tunneling microscopy conducted in scanning tunneling spectroscopy mode. Following two distinct sample preparation protocols for each enantiomer, we generate supramolecular polymers with opposite handedness and specific spin transport characteristics. Our primary focus centers on chiral π-conjugated building blocks, with the aim of advancing novel systems that can inspire the organic spintronics community from a supramolecular chemistry level. [ABSTRACT FROM AUTHOR]

A gold surface is functionalized by chemisorption of the enantiopure N,N′-bis-[2,2′;5′,2″]tert-thiophene-5-yl methylcyclohexane-1,2-diamine (2T3N), a chiral oligothiophene derivative, via overnight incubation in a 2T3N ethanol solution. The Au|2T3N interface is characterized by x-ray photoelectron circular dichroism and comparing x-ray photoemission spectroscopy and electro-desorption results. Charge transmission at the Au|2T3N| solution interface is characterized by recording the cyclic voltammetry of the Fe(III)/Fe(II) reversible redox couple, finding a charge transfer rate constant, k°, variation from 1 × 10−1 to 3.3 × 10−2 cm s−1, when comparing the bare Au and the Au|2T3N interfaces, respectively. The "anomalous" high value of k° found for the chiral Au|2T3N interface can be rationalized on the basis of the chiral-induced spin selectivity effect, as further proved by magnetic–conductive atomic force microscopy measurements at room temperature. A spin polarization of about 30% is found. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have emerged as a promising technology for renewable energy generation due to their low cost, lightweight, flexibility, and compatibility with roll-to-roll manufacturing. However, OSCs still face challenges in achieving high power conversion efficiency (PCE) due to various factors, including recombination loss. In this study, we investigated the effect of introducing a layer of eight atomic percent gadolinium-doped zinc oxide (Zn0.92Gd0.08O) between the poly(3-hexylthiophene) (P3HT): [6,6]-phenyl butyric acid methyl ester (PCBM) active layer and the fluorine-doped tin oxide (FTO) electrode of the OSC. The reference cell, which has an Au/P3HT:PCBM/ZnO/FTO structure, exhibits a PCE of 0.52%. Remarkably, when the Zn0.92Gd0.08O layer was inserted (Au/P3HT:PCBM/Zn0.92Gd0.08O/FTO), the PCE increased significantly to 3.42%, which is more than six times the increase. Through further analysis, we present that the insertion of the Zn0.92Gd0.08O layer induces spin polarization in the P3HT:PCBM layer, leading to enhanced charge transport and reducing the recombination rate. Based on the findings, it can be concluded that the Zn0.92Gd0.08O film can potentially improve OSC performance. [ABSTRACT FROM AUTHOR]

Electron transport through a variety of helical structures has been shown to exhibit high-efficiency spin filtering, which is called chirality-induced spin selectivity (CISS). In this paper, we consider a helical chain of atomic p orbitals, which has been employed as a model in exploring the mechanism of CISS in previous theories, and show that the interatomic hopping along the helical chain induces an effective magnetic field (EMF) acting on the atomic orbital angular momentum (OAM). In chains where the curvature and torsion of the helix are small, we find that the EMF on the binormal component of the atomic OAM is created by the curvature, while that on the tangential component is produced by the torsion. We show that such coupling of the atomic OAM and the interatomic hopping leads to current-induced orbital and spin polarizations. We expect that the present coupling, which is expressed locally, can be used to estimate orbital and spin polarizations locally induced in molecules and solids. [ABSTRACT FROM AUTHOR]

Nonlocal spin polarization phenomena are thoroughly investigated in the devices made of chiral metallic single crystals of CrNb3S6 and NbSi2 as well as of polycrystalline NbSi2. We demonstrate that simultaneous injection of charge currents in the opposite ends of the device with the nonlocal setup induces the switching behavior of spin polarization in a controllable manner. Such a nonlocal spin polarization appears regardless of the difference in the materials and device dimensions, implying that the current injection in the nonlocal configuration splits spin-dependent chemical potentials throughout the chiral crystal even though the current is injected into only a part of the crystal. We show that the proposed model of the spin dependent chemical potentials explains the experimental data successfully. The nonlocal double-injection device may offer significant potential to control the spin polarization to large areas because of the nature of long-range nonlocal spin polarization in chiral materials. [ABSTRACT FROM AUTHOR]

The control of electron spin, crucial to the stability of matter, offers new possibilities for manipulating the properties of molecules and materials with potential applications in spintronics and chemical reactions. Recent experiments have demonstrated that electron transmission through chiral molecules depends on the electron spin orientation, a phenomenon known as chiral-induced spin selectivity (CISS). In this study, we show that CISS can be observed in achiral systems driven by an external circularly polarized laser field in the framework of Floquet engineering. By using the Floquet theory for a time-periodically driven system to investigate spin-dependent electron transport in a two-terminal setup, we demonstrate that the spin polarization can approach unity if the light intensity is sufficiently strong, the rate of dephasing is sufficiently low, and the average chemical potential of the two leads is within an appropriate range of values, which is narrow because of the high frequency of the laser field. To obtain a broader range of energies for large spin polarization, a combination of chiral molecules and light–matter interactions is considered, and the spin polarization of electrons transported through a helical molecule driven by a laser field is evaluated. [ABSTRACT FROM AUTHOR]

It has been demonstrated previously that electrons interact differently with chiral molecules depending on their polarization. For enantiomeric pure monolayers of heptahelicene, opposite asymmetries in spin polarization were reported and attributed to the so-called chirality-induced spin selectivity effect. However, these promising proof-of-concept photoemission experiments lack the angular and energy resolution that could provide the necessary insights into the mechanism of this phenomenon. In order to fill in the missing gaps, we provide a detailed spin- and angle-resolved photoemission spectroscopy study of heptahelicene layers on a Cu(111) substrate. Throughout the large accessible energy and angle range, no chirality induced spin asymmetry in photoemission could be observed. Possible reasons for the absence of signatures of the spin-dependent electron transmission through the chiral molecular layer are briefly discussed. [ABSTRACT FROM AUTHOR]

Bio-spinterfaces present numerous opportunities to study spintronics across the biomolecules attached to (ferro)magnetic electrodes. While it offers various exciting phenomena to investigate, it is simultaneously challenging to make stable bio-spinterfaces as biomolecules are sensitive to many factors that it encounters during thin-film growth to device fabrication. The chirality-induced spin-selectivity effect is an exciting discovery, demonstrating an understanding that a specific electron's spin (either up or down) passes through a chiral molecule. The present work utilizes Ustilago maydis Rvb2 protein, an ATP-dependent DNA helicase (also known as Reptin), to fabricate bio-spintronic devices to investigate spin-selective electron transport through the protein. Ferromagnetic materials are well-known for exhibiting spin-polarization, which many chiral and biomolecules can mimic. We report herein spin-selective electron transmission through Rvb2 that exhibits 30% spin polarization at a low bias (+0.5 V) in a device configuration, Ni/Rvb2 protein/indium tin oxide measured under two different magnetic configurations. Our findings demonstrate that biomolecules can be put in circuit components without any expensive vacuum deposition for the top contact. The present study holds a remarkable potential to advance spin-selective electron transport in other biomolecules, such as proteins and peptides, for biomedical applications. [ABSTRACT FROM AUTHOR]

Different from conventional ferromagnetic methods, producing a spin-polarized current through electrical ways in spintronic devices can greatly increase operating speed, reduce power consumption, and improve device integration. Inspired by recent experimental progress on the synthesis of a heptauthrene molecule, we investigate its spin-dependent transport contacted with Au electrodes through first-principles calculations. By applying a gate voltage, the transmission can be switched between completely spin-up and spin-down polarized states, achieving an electrically controlled dual-spin filter. Furthermore, a fine tuning on the spin polarization, between 100% and − 100%, can also be realized, where the transport with any ratio of spin-up to spin-down electron quantities can be realized beyond the traditional devices. The peculiar transmission spectra and their shift are found to play crucial roles, where transmission peaks distribute on both sides of the Fermi level with opposite spin components. Such a spin-polarization modulating effect is found to be robust to the molecule-electrode contacting site, indicating it is an intrinsic feature of such systems. Moreover, the dimension of the device is at the single-molecule level, suggesting great application potential. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferromagnetic and antiferromagnetic second-order topological insulators (SOTIs) coexisting with valley polarization have received increasing attention recently, while 2D valley-polarized ferrimagnetic (ferri-valley) SOTI has not been reported yet. In this work, we propose an effective six-band tight-binding model based on structural symmetry to confirm the possibility of coexistence of ferrimagnetism, second-order topological corner states, and valley polarization in 2D systems, and predict Mo2CSCl monolayer as the robust 2D ferri-valley SOTI with good structural stability, considerable Curie temperature estimated to be 100 K, and distinct valley polarization up to 109 meV under out-of-plane exchange field based on our model and first-principles calculations. Also, we find that the spin polarization direction of corner states combined with valley polarization can be controlled by switching the direction of the magnetization direction using an external magnetic field. These findings of the combination of intrinsic ferrimagnetism, second-order topological properties, and valley polarization in single 2D materials provide an ideal platform for practical applications in multifield-control spintronic devices. [ABSTRACT FROM AUTHOR]

Magnetic field effects have received widespread attention due to their ability to enhance the process of water splitting at multiple scales. However, a systematic and comprehensive understanding of the source of the magnetic effect and the magnetic modulation of magnetic catalysts is lacking. This perspective focuses on recent advancements in harnessing external magnetic field to improve electrocatalytic water splitting and suggests future directions. First, the mechanism of several magnetic effects and their effects on water splitting are elaborated in detail, including the magnetohydrodynamic effect, magnetothermal effect, spin polarization effect, and magnetoresistance effect. Then, the classification and construction strategies of magnetic effect catalysts are summarized, primarily divided into single metal/alloy catalysts, metal oxide-based catalysts, and other magnetic catalysts. Finally, the challenges and potential perspective of magnetic field-enhanced water splitting are discussed, including mechanism study, in situ characterization, and multi-field synergy effects. [ABSTRACT FROM AUTHOR]

This study investigates magnetosonic shock waves in a spin-polarized three-component quantum plasma using the quantum magnetic hydrodynamic model. We explore the influence of spin effects, specifically spin magnetization current and spin pressure, on shock wave behavior. Numerical analysis of the linear dispersion relation under varying parameters such as positron imbalance, spin polarization ratio, plasma beta, quantum diffraction, and magnetic diffusivity reveals differential impacts, with diffusion exerting significant influence on the plasma frequency. Our findings highlight the sensitivity discrepancy between the real and imaginary parts of the dispersion relation. Furthermore, nonlinear behavior of magnetosonic shock waves is examined via the Korteweg–de Vries–Burgers equation, showcasing transitions between oscillatory and monotonic wave patterns based on changes in dimensionless parameters. Notably, we observe the combined effects of spin-up and spin-down positrons with spin-up and spin-down electrons on shock wave dynamics, contributing to a deeper understanding of spin-plasma interactions with implications across various fields. [ABSTRACT FROM AUTHOR]

Combining chirality with ferromagnetism is challenging in organic materials and may bring potential application for the cross-integration of multiple disciplines. In this work, we achieved the intrinsic coexistence of chirality and spontaneous spin polarization in the diblock copolymers, where left-handed and right-handed circularly polarized lights present tunability on both the circular dichroism and spin polarization. Without electron dependence of transport in chiral copolymer, chirality is still coupled with spin. The phenomenon observed here is not the traditional chirality induced spin selectivity effect. Moreover, the electric field could also effectively tune the chirality dependence of circular dichroism to further affect the magnitude of spin polarization. Thus, a strong relationship between the chirality and spin polarization is formed in chiral copolymers. In addition, because of the different molecular packing for chiral enantiomers, electron–phonon coupling strengths are different to lead to a difference in spin polarization. Overall, the properties of chirality, spontaneous spin polarization, and photon-chirality-spin coupling are developed and studied, which effectively promotes the ability of potential applications of chiral copolymers. [ABSTRACT FROM AUTHOR]

Second-order Møller-Plesset perturbation theory (MP2) often breaks down catastrophically in small-gap systems, leaving much to be desired in its performance for myriad chemical applications such as noncovalent interactions, thermochemistry, and dative bonding in transition metal complexes. This divergence problem has reignited interest in Brillouin-Wigner perturbation theory (BWPT), which is regular at all orders but lacks size consistency and extensivity, severely limiting its application to chemistry. In this work, we propose an alternative partitioning of the Hamiltonian that leads to a regular BWPT perturbation series that, through the second order, is size-extensive, size-consistent (provided its Hartree–Fock reference is also), and orbital invariant. Our second-order size-consistent Brillouin-Wigner (BW-s2) approach can describe the exact dissociation limit of H2 in a minimal basis set, regardless of the spin polarization of the reference orbitals. More broadly, we find that BW-s2 offers improvements relative to MP2 for covalent bond breaking, noncovalent interaction energies, and metal/organic reaction energies, although rivaling coupled-cluster with single and double substitutions for thermochemical properties. [ABSTRACT FROM AUTHOR]

The theory of the magnetic coupling between the localized spins, mediated by the mobile excess electron, is generalized to the case of a trigonal, six-center, four-electron molecule with partial valence delocalization. The combination of the electron transfer occurring within the valence-delocalized subsystem and the interatomic exchange producing coupling of the spin of the mobile electron of valence-delocalized fragment with the three localized spins forming the valence-localized subsystem leads to the appearance of a special kind of double exchange (DE), termed the "external core double exchange" (ECDE), in order to distinguish such DE from the conventional "internal core double exchange" for which the mobile electron is coupled with the spin-cores on the same center via the intra-atomic exchange. The effect of the ECDE on the ground spin state of the considered trigonal molecule is compared with earlier reported effect produced by DE in the four-electron, mixed-valence (MV) trimer. A high diversity of the ground spin states is revealed, depending on the relative magnitudes and signs of the electron transfer and interatomic exchange parameters, with part of these states not appearing to be the ground states in a trigonal trimer exhibiting DE. We briefly discuss some examples of trigonal MV systems from the point of view of the possibility to have different combinations of signs of the transfer and exchange parameters and, accordingly, different ground spin states. The tentative role of the considered systems in molecular electronics and spintronics is also noticed. [ABSTRACT FROM AUTHOR]

In this paper, we outline a physically motivated framework for describing spin-selective recombination processes in chiral systems, from which we derive spin-selective reaction operators for recombination reactions of donor–bridge–acceptor molecules, where the electron transfer is mediated by chirality and spin–orbit coupling. In general, the recombination process is selective only for spin-coherence between singlet and triplet states, and it is not, in general, selective for spin polarization. We find that spin polarization selectivity only arises in hopping-mediated electron transfer. We describe how this effective spin-polarization selectivity is a consequence of spin-polarization generated transiently in the intermediate state. The recombination process also augments the coherent spin dynamics of the charge separated state, which is found to have a significant effect on the recombination dynamics and to destroy any long-lived spin polarization. Although we only consider a simple donor–bridge–acceptor system, the framework we present here can be straightforwardly extended to describe spin-selective recombination processes in more complex systems. [ABSTRACT FROM AUTHOR]

An experimental and computational optical pump-probe model is constructed, which utilizes two ultrafast pump pulses within the repetition period of a mode-locked laser to generate electron spin polarization. This report focuses on the effects of resonant spin amplification induced by an infinite train of the two-pump pulses. The first pump pulse is used to generate ordinary resonant spin amplification spectra, while the second pump pulse is used to manipulate the generated spectra. This model gives control of the accumulation of spin polarized electrons along a magnetic field by selecting the temporal separation of the two-pump pulses. The computational model accurately predicts and agrees with the experimental results, which shows manipulation of resonant spin peaks that are no longer entirely dependent on the external magnetic field. This two-pump model and the associated manipulations of resonant spin peaks can be used as a platform to construct and conceptualize resonant spin amplification-based optospintronic devices and applications. [ABSTRACT FROM AUTHOR]

Photoexcitable donor–bridge–acceptor (D–B–A) molecules that support intramolecular charge transfer are ideal platforms to probe the influence of chiral induced spin selectivity (CISS) in electron transfer and resulting radical pairs. In particular, the extent to which CISS influences spin polarization or spin coherence in the initial state of spin-correlated radical pairs following charge transfer through a chiral bridge remains an open question. Here, we introduce a quantum sensing scheme to measure directly the hypothesized spin polarization in radical pairs using shallow nitrogen–vacancy (NV) centers in diamond at the single- to few-molecule level. Importantly, we highlight the perturbative nature of the electron spin–spin dipolar coupling within the radical pair and demonstrate how Lee–Goldburg decoupling can preserve spin polarization in D–B–A molecules for enantioselective detection by a single NV center. The proposed measurements will provide fresh insight into spin selectivity in electron transfer reactions. [ABSTRACT FROM AUTHOR]

Spin polarization in the multiphoton above-threshold ionization of 5p3/2- and 5p1/2-electrons of Xe with intense 395nm, circularly polarized laser pulses, is investigated theoretically. For this purpose, we solve the time-dependent Schrödinger equation on the basis of spherical spinors. We, thus, simultaneously propagate the spin-up and spin-down single-active-electron wave packets, driven by the laser pulses in the ionic potential, which includes the spin–orbit interaction explicitly. The present theoretical results are in good agreement with the recent experimental results [D. Trabert et al., Phys. Rev. Lett. 120, 043202 (2018)]. [ABSTRACT FROM AUTHOR]

Valleytronics has attracted much attention due to its potential applications in information progress and data storage. In this paper, monolayer Cr2S3 is proven to be a ferromagnetic (FM) semiconductor by using first-principles calculations. Moreover, monolayer Cr2S3 exhibits a perpendicular magnetic anisotropy energy of 30 μeV/f.u. Surprisingly, monolayer Cr2S3 presents spontaneous valley polarization, which means that it will be nonvolatile for data storage. Notably, monolayer Cr2S3 changes to an antiferromagnetic (AFM) state from the original FM state under biaxial tensile strain, and its easy axis will be reorientated from out-of-plane to in-plane when the compressive strain is larger than −2%. Importantly, for AFM monolayer Cr2S3, the valley polarization reversion can be realized by an external electric field along the z direction. In brief, valley polarization has been achieved in both FM and AFM monolayer Cr2S3, which is very rare in other valleytronics research. The present research provides a tantalizing candidate for realizing and manipulating valley and spin physics. [ABSTRACT FROM AUTHOR]

High spin-injection-efficiency (SIE) and thermal spin-filter-effect (SFE) from a magnetic material to a barrier material are crucial to the high performance of a spintronic device and a spin caloritronic device, respectively. By performing a nonequilibrium Green's function combined with first-principles calculations, we study the voltage-driven and temperature-driven spin transport properties of a half Heusler alloy RuCrAs based spin valve with different atom-terminated interfaces. The spin valve with a CrAs-top (or Ru-top) interface structure has an ultrahigh equilibrium magnetoresistance (MR) ratio of ∼1.56 × 109% (or ∼5.14 × 108%), ∼100% SIE, a large MR ratio, and high spin current intensity under bias voltage, suggesting that it has a great potential application in spintronic devices. The spin valve with the CrAs-top (or CrAs-bri) interface structure has a perfect SFE due to its very high spin polarization of temperature-driven currents, and it is useful in spin caloritronic devices. [ABSTRACT FROM AUTHOR]

Recent theoretical and experimental discoveries of two-dimensional (2D) ferromagnetic (FM) materials have sparked intense interest for their potential applications in spintronics. 2D FM materials with high spin polarization are extremely desirable for future low-dimensional spintronics. Half-metallicity plays a key role in the development of such devices. Here, we reported a new 2D nanomagnet VClI 2 using the first-principles based density functional theory calculations. VClI 2 shows an exciting half-metallic character with a wide half-metallic gap of 0.4 eV. The ground state favors ferromagnetic coupling with a Curie temperature T c of 21 K. The half-metallicity with a FM ground state is further achieved by the application of an external strain and by the combined effects of the strain and the electric field. A phase transition from a half-metallic → semiconductor → metal was further observed under different stimuli with an antiferromagnetic ground state. At E z = 7.5 V/nm and in the presence of η = 5 % strain, the calculated T c is estimated at 35 K, which shows a 67% increment than the T c observed in the unstrained condition. The fascinating and unique properties suggest that VClI 2 is a promising two-dimensional ferromagnetic half-metal, which can be useful for applications in future memory devices to enrich the 2D magnetic materials library. [ABSTRACT FROM AUTHOR]

Recent theoretical and experimental discoveries of two-dimensional (2D) ferromagnetic (FM) materials have sparked intense interest for their potential applications in spintronics. 2D FM materials with high spin polarization are extremely desirable for future low-dimensional spintronics. Half-metallicity plays a key role in the development of such devices. Here, we reported a new 2D nanomagnet VClI 2 using the first-principles based density functional theory calculations. VClI 2 shows an exciting half-metallic character with a wide half-metallic gap of 0.4 eV. The ground state favors ferromagnetic coupling with a Curie temperature T c of 21 K. The half-metallicity with a FM ground state is further achieved by the application of an external strain and by the combined effects of the strain and the electric field. A phase transition from a half-metallic → semiconductor → metal was further observed under different stimuli with an antiferromagnetic ground state. At E z = 7.5 V/nm and in the presence of η = 5 % strain, the calculated T c is estimated at 35 K, which shows a 67% increment than the T c observed in the unstrained condition. The fascinating and unique properties suggest that VClI 2 is a promising two-dimensional ferromagnetic half-metal, which can be useful for applications in future memory devices to enrich the 2D magnetic materials library. [ABSTRACT FROM AUTHOR]

Generally, Co-based Heusler alloys are the center of interest because of their properties such as high Curie temperature, spin polarization, and high value of exchange bias. Herein, we have used the macroscopic technique to probe the low-temperature exotic properties of M1.5Co0.5FeAl. First, we have analyzed the dc magnetization data, and it unfolds the presence of a glassy phase at 33 K. The cluster spin glass phase is authenticated by measuring ac susceptibility. Furthermore, using empirical models like power law and Vogel–Fulcher fitting, the relaxation time for the spin is of the order of τ ∼ 10−9 s, confirming the presence of a cluster spin glass in Mn1.5Co0.5FeAl below an irreversible temperature. The H–T phase space diagram ensures that it follows the Ising spin model. Furthermore, the glassy phase of the system is confirmed by magnetic relaxation, memory effect, and the presence of an exchange bias instead of a minor loop below spin-freezing temperature (Tf ∼ 33 K). [ABSTRACT FROM AUTHOR]

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]

Semiconductor spintronics has brought about revolutionary application prospects in future electronic devices. The tunnel junction plays a key role in achieving efficient spin injection in semiconductors. This work employed the GaN semiconductor as a room-temperature spin injection system, taking advantage of its weak spin–orbit coupling and spin scattering. By introducing a lattice-matched AlN barrier layer to improve the tunneling interface, advanced spin injection and transport were realized compared with traditional oxide barriers. The spin polarization was further improved by modulating the applied bias, and a bias-controlled tunneling enhancement mechanism was revealed. Consequently, we demonstrated a high record of spin polarization of 20.5%. This work paves a feasible route for achieving efficient spin injection and transport in GaN, which will further promote the development of room-temperature and high-performance spintronic devices. [ABSTRACT FROM AUTHOR]

The magnetic tunnel junctions (MTJs) based on van der Waals (vdW) materials possess atomically smooth interfaces with minimal element intermixing. This characteristic ensures that spin polarization is well maintained during transport, leading to the emergence of richer magnetoresistance behaviors. Here, using all 2D vdW MTJs based on magnetic metal Fe3GeTe2 and non-magnetic semiconductor MoSe2, we demonstrate that the magnitude and even sign of the magnetoresistance can be tuned by the applied voltage. The sign inversion of the magnetoresistance is observed in a wide temperature range below the Curie temperature. This tunable magnetoresistance sign may be attributed to the spin polarizations of the tunneling carriers and the band structure of the two ferromagnetic electrodes. Such robust electrical tunability of magnetoresistance extends the functionalities of low-dimensional spintronics and makes it more appealing for next-generation spintronics with all-vdW MTJs. [ABSTRACT FROM AUTHOR]

The recent emergence of two-dimensional metal-organic framework (MOF) materials with nontrivial magnetic and electronic properties has attracted great interest in spintronics. Here, we theoretically demonstrate the synthesis of a coloring-triangle latticed 2D MOF by assembling 2,3,6,7,10,11-hexahydroxytriphenylene (H6HOTP) species and threefold coordinated Mn atoms, namely, 2D Mn-HOTP. The electronic structure calculations shown that 2D Mn-HOTP exhibits coexistence of bipolar magnetic semiconducting and topological behavior. 2D Mn-HOTP is an intrinsic bipolar magnetic semiconductor with a small spin-flip band gap of 0.21 eV and relatively large spin-conserving band gaps of 0.34 and 0.74 eV. Electrical/hole doping can induce the transformation of 2D Mn-HOTP into half-metal conduction with controllable spin polarization direction. In addition, the organic HOTP ligands containing coloring-triangle lattice enable the formation of p-orbital single polarized Dirac cones and flat bands, which exhibit the topological properties such as nonzero Chern number and nontrivial edge states near the Fermi level. The Dirac points and flat bands can be selectively detected at the Fermi level with experimentally achievable electron and hole concentrations of 5.19 and 0.91 × 1013 cm−2, respectively. These results not only highlight that 2D Mn-HOTP MOF is a promising candidate for developing spintronic devices but also provide an ideal platform to explore kagome-like correlated quantum states. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) intrinsic ferromagnetic (FM) materials with high Curie temperatures (Tc), large perpendicular magnetic anisotropy (PMA), and large spin polarization are desirable for atomically thin spintronic devices. Herein, we propose a 2D intrinsic FM material Mn2GeI2 monolayer with thermodynamical stability and outstanding FM properties using first-principles calculations. Our calculations show that Mn2GeI2 monolayer is a half-metal with a spin gap of 1.76 eV, which ensures 100% spin polarization ratio at the Fermi level. Importantly, Mn2GeI2 monolayer has a large PMA energy of 2.90 meV and a high Tc of 648 K, ideal for practical applications at room temperature. Further in-depth investigation of microscopic coupling in the Mn2GeI2 monolayer reveals that the robust ferromagnetism mainly resulted from the synthetic effect of Ruderman–Kittel–Kasuya–Yosida exchange interaction between the Mn ion layers and superexchange interaction within the Mn ion layers. Our results give insights into the structure and electronic and magnetic properties of Mn2GeI2 monolayer and provide a promising candidate for 2D spintronic devices. [ABSTRACT FROM AUTHOR]

Exploring the spin transport characteristics of magnetic tunnel junctions based on half-metallic Heusler holds significance, not only in unraveling the fundamental physics at play but also in advancing applications of spintronic devices. Here, density functional theory in conjunction with non-equilibrium Green's functions has been systematically employed to investigate two prominent Heusler alloys, Co2CrAl and CoFeCrAl, which are of direct interest to the candidates of magnetic tunnel junction. The electronic structures of two Hesler alloys reveal that both exhibit characteristics of half-metallic ferromagnets, featuring a substantial spin-down bandgap and achieving 100% spin polarization. The tunneling magnetoresistance ratios obtained for Co2CrAl/AlP/Co2CrAl and CoFeCrAl/AlP/CoFeCrAl magnetic tunnel junctions are determined to be 173% and 59%, respectively, with the former exhibiting superior device characteristics. Therefore, the Co2CrAl/AlP-based magnetic tunnel junction demonstrates ideal performance, providing new opportunities for two-dimensional spintronics. [ABSTRACT FROM AUTHOR]

Randomly mixing ferromagnetic (FM) and antiferromagnetic (AFM) elements in high-entropy alloys (HEAs) can create fluctuating local magnetic moments that influence the energetics of point defects. In this study, we employed first-principles calculations to investigate the influence of magnetic properties on vacancy migration energy in Fe49.5Mn29.4Co10.1Cr10.1C0.9, alongside equiatomic NiCoFeCrMn alloy. By examining structures with paramagnetism, ferromagnetism, and no spin polarization, our study reveals significant impacts of magnetic interactions on vacancy migration barriers, potentially altering the sequence of elemental migration energies if overlooked. In Fe49.5Mn29.4Co10.1Cr10.1C0.9, the order of vacancy migration barriers is Co > Fe > Mn > Cr across all magnetic states, suggesting the dominant roles of atomic properties and inherent chemical bonding. Conversely, the NiCoFeCrMn HEA exhibits a pronounced magnetic state-dependent elemental migration energy order, indicating that magnetic interactions significantly influence vacancy migration behavior in this alloy. In addition, while FM elements generally exhibit higher migration barriers, AFM elements display lower barriers in the investigated Cantor alloys, with notable variations between the studied compositions. These findings underscore the critical role of magnetism in accurate migration energy calculations, which is important for studying chemically biased diffusion and radiation-induced segregation in HEAs. [ABSTRACT FROM AUTHOR]

The spintronic properties of cubic ZrO2 (c-ZrO2) nanosheets with intrinsic defects and transition metal (TM) elements doping have been systematically studied by first-principle calculation. The results show that impurity Fe has the lowest formation energy in each monolayer compared to other defects. The most stable (111) nanosheet, coupled with the higher defect formation energy, tends to disintegrate. Only Zr vacancy (VZr) on the (110) surface or O vacancy (VO) on the (111) surface can generate a ferromagnetic ground state, while other intrinsic defects cannot introduce spin polarization. Ni-doped (110) monolayer cannot introduce a local magnetic moment, while Fe and Co can. The magnetic moments produced by Fe, Co, and Ni in the (111) sheet are 2, 4, and 1 µB, respectively. Further investigation revealed that the magnetism was mainly contributed by the d orbitals of the TM atom and the p orbitals of the surrounding O atoms. Magnetic couplings show that only Co–Co doped monolayers can produce macroscopic magnetism. These are predicted to produce TCs Curie temperature above room temperature when Co–Co distances are 5.070 and 6.209 Å on the (110) surface and 7.170 and 9.485 Å on the (111) surface. The research is beneficial to the refinement of the development of spintronics. [ABSTRACT FROM AUTHOR]