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Electrical generation and transduction of polarized electron spins in semiconductors (SCs) are of central interest in spintronics and quantum information science. While spin generation in SCs is frequently realized via electrical injection from a ferromagnet (FM), there are significant advantages in nonmagnetic pathways of creating spin polarization. One such pathway exploits the interplay of electron spin with chirality in electronic structures or real space. Here, utilizing chirality-induced spin selectivity (CISS), the efficient creation of spin accumulation in n-doped GaAs via electric current injection from a normal metal (Au) electrode through a self-assembled monolayer (SAM) of chiral molecules (α-helix l-polyalanine, AHPA-L), is demonstrated. The resulting spin polarization is detected as a Hanle effect in the n-GaAs, which is found to obey a distinct universal scaling with temperature and bias current consistent with chirality-induced spin accumulation. The experiment constitutes a definitive observation of CISS in a fully nonmagnetic device structure and demonstration of its ability to generate spin accumulation in a conventional SC. The results thus place key constraints on the physical mechanism of CISS and present a new scheme for magnet-free SC spintronics.

The propagation of spin waves in magnetically ordered systems has emerged as a potential means to shuttle quantum information over large distances. Conventionally, the arrival time of a spin wavepacket at a distance, d, is assumed to be determined by its group velocity, vg. Here, we report time-resolved optical measurements of wavepacket propagation in the Kagome ferromagnet Fe3Sn2 that demonstrate the arrival of spin information at times significantly less than d/vg. We show that this spin wave "precursor" originates from the interaction of light with the unusual spectrum of magnetostatic modes in Fe3Sn2. Related effects may have far-reaching consequences toward realizing long-range, ultrafast spin wave transport in both ferromagnetic and antiferromagnetic systems.

Molecular semiconductors (MSCs), characterized by a longer spin lifetime than most of other materials due to their weak spin relaxation mechanisms, especially at room temperature, together with their abundant chemical tailorability and flexibility, are regarded as promising candidates for spintronic applications. Molecular spintronics, as an emerging subject that utilizes the unique properties of MSCs to study spin-dependent phenomena and properties, has attracted wide attention. In molecular spintronic devices, MSCs play the role as medium for information transport, process, and storage, in which the efficient spin inject–transport process is the prerequisite. Herein, we focus mainly on summarizing and discussing the recent advances in theoretical principles towards spin transport of MSCs in terms of the injection of spin-polarized carriers through the ferromagnetic metal/MSC interface and the subsequent transport within the MSC layer. Based on the theoretical progress, we cautiously present targeted design strategies of MSCs that contribute to the optimization of spin-transport efficiency and give favorable approaches to exploring accessional possibilities of spintronic materials. Finally, challenges and prospects regarding current spin transport are also presented, aiming to promote the development and application of the rosy and energetic field of molecular spintronics. [ABSTRACT FROM AUTHOR]

The intrinsic properties of predesignable topologies and tunable electronic structures, coupled with the increase of electrical conductivity, make two‐dimensional metal–organic frameworks (2D MOFs) highly prospective candidates for next‐generation electronic/spintronic devices. In this Minireview, we present an outline of the design principles of 2D MOF‐based spintronics materials. Then, we highlight the spin‐transport properties of 2D MOF‐based organic spin valves (OSVs) as a notable achievement in the progress of 2D MOFs for spintronics devices. After that, we discuss the potential for spin manipulation in 2D MOFs with bipolar magnetic semiconductor (BMS) properties as a promising field for future research. Finally, we provide a brief summary and outlook to encourage the development of novel 2D MOFs for spintronics applications. [ABSTRACT FROM AUTHOR]

Here we propose a mechanism by which spin-polarization can be generated dynamically in chiral molecular systems undergoing photoinduced electron transfer. The proposed mechanism explains how spin-polarization emerges in systems where charge transport is dominated by incoherent hopping, mediated by spin-orbit and electronic exchange couplings through an intermediate charge transfer state. We derive a simple expression for the spin-polarization that predicts a nonmonotonic temperature dependence, consistent with recent experiments, and a maximum spin-polarization that is independent of the magnitude of the spin-orbit coupling. We validate this theory using approximate quantum master equations and the numerically exact hierarchical equations of motion. The proposed mechanism of chirality induced spin selectivity should apply to many chiral systems, and the ideas presented here have implications for the study of spin transport at temperatures relevant to biology and provide simple principles for the molecular control of spins in fluctuating environments.

Single‐molecule magnetic junctions serve as an important component for the manipulation of spin‐polarized currents by chemical modifications and control of magnetic interactions in spintronic devices. We employed the nonequilibrium green function and spin‐polarized density functional theory simulations to investigate the performance of molecular junctions bearing an organic radical as spin filters. A spin‐polarized current could be generated using the junctions and, moreover, the spin‐filtering efficiency could be tuned by varying the number of magnetic units. Spin orbital and density of states analyses revealed the relationship effect of the shapes and energy levels of the dominant electron‐conducting channels in the spin‐filtering efficiency. Thus, the use of a tunable organic magnetic molecular junction system is an appealing approach for regulating spin‐polarized currents in spintronic devices. [ABSTRACT FROM AUTHOR]

Because spin‐orbit coupling in wurtzite semiconductors is relatively weak compared with that in zincblende ones, the III‐nitride semiconductor GaN is a promising material for high‐performance optical semiconductor spintronic devices such as spin lasers. For the purpose of reducing the operating power of spin lasers, it is necessary to demonstrate highly efficient electrical spin injection from a ferromagnetic material into GaN with a low‐resistance contact. Here, an epitaxial half‐metallic Heusler alloy Co2FeAlxSi1−x(CFAS)/GaN heterostructure is developed by inserting an ultrathin Co layer between the CFAS and GaN. The CFAS/n+‐GaN heterojunctions clearly show tunnel conduction with very small rectification and a low resistance‐area product of ≈3.8 kΩµm2, which is several orders of magnitude smaller than those reported in previous work, at room temperature. Nonlocal spin signals and a Hanle effect curve are observed at low temperatures using lateral spin‐valve devices with the CFAS/n+‐GaN contacts, suggesting pure spin current transport in bulk GaN. The spin transport is observed at temperatures as high as room temperature, with a high spin polarization of 0.2 at a low bias voltage less than 2.0 V. This study is expected to open a path to GaN‐based spintronic devices with highly spin‐polarized and low‐resistance contacts. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJs) based on novel states of two-dimensional (2D) magnetic materials will significantly improve the value of the tunneling magnetoresistance (TMR) ratio. However, most 2D magnetic materials exhibit low critical temperatures, limiting their functionality to lower temperatures rather than room temperature. Moreover, most MTJs experience the decay of TMR ratio at large bias voltages within a low spin injection efficiency (SIE). Here, we construct a series of MTJs with Weyl half-semimetal (WHSM, e.g. MnSiS _3 , MnSiSe _3 , and MnGeSe _3 monolayers) as the electrodes and investigate the spin-dependent transport properties in these kind of lateral heterojunctions by employing density functional theory combined with non-equilibrium Green’s function method. We find that an ultrahigh TMR (∼10 ^9 %) can be obtained firmly at a small bias voltage and maintains a high SIE even at a large bias voltage, and MnSiSe _3 monolayer is predicted to exhibit a high critical temperature. Additionally, we reveal that the same structure allows for the generation of fully spin-polarized photocurrent, irrespective of the polarization angle. These findings underscore the potential of WHSMs as candidate materials for high-performance spintronic devices.

Abstract Because spin‐orbit coupling in wurtzite semiconductors is relatively weak compared with that in zincblende ones, the III‐nitride semiconductor GaN is a promising material for high‐performance optical semiconductor spintronic devices such as spin lasers. For the purpose of reducing the operating power of spin lasers, it is necessary to demonstrate highly efficient electrical spin injection from a ferromagnetic material into GaN with a low‐resistance contact. Here, an epitaxial half‐metallic Heusler alloy Co2FeAlxSi1−x(CFAS)/GaN heterostructure is developed by inserting an ultrathin Co layer between the CFAS and GaN. The CFAS/n+‐GaN heterojunctions clearly show tunnel conduction with very small rectification and a low resistance‐area product of ≈3.8 kΩµm2, which is several orders of magnitude smaller than those reported in previous work, at room temperature. Nonlocal spin signals and a Hanle effect curve are observed at low temperatures using lateral spin‐valve devices with the CFAS/n+‐GaN contacts, suggesting pure spin current transport in bulk GaN. The spin transport is observed at temperatures as high as room temperature, with a high spin polarization of 0.2 at a low bias voltage less than 2.0 V. This study is expected to open a path to GaN‐based spintronic devices with highly spin‐polarized and low‐resistance contacts.

Organic spintronics has caused a huge revolution in creating highly efficient low‐power circuits. Spin manipulation in organic cocrystals has become a promising strategy to uncover more chemicophysical properties for diverse applications. In this Minireview, we summarize the recent advancements of spin properties in organic charge‐transfer cocrystals, and briefly describe the possible mechanisms behind them. Beside the known spin properties (spin multiplicity, mechanoresponsive spin, chiral orbit and spin‐crossover) in binary/ternary cocrystals, other spin phenomena in radical cocrystals and spin transport are also summarized and discussed. Hopefully, deep understanding of current achievements, challenges and perspectives will offer the clear direction for the introduction of spin in organic cocrystals. [ABSTRACT FROM AUTHOR]

The propagation of spin waves in magnetically ordered systems has emerged as a potential means to shuttle quantum information over large distances. Conventionally, the arrival time of a spin wavepacket at a distance, d, is assumed to be determined by its group velocity, vg. Here, we report time-resolved optical measurements of wavepacket propagation in the Kagome ferromagnet Fe3Sn2 that demonstrate the arrival of spin information at times significantly less than d=vg. We show that this spin wave "precursor" originates from the interaction of light with the unusual spectrum of magnetostatic modes in Fe3Sn2. Related effects may have far-reaching consequences toward realizing long-range, ultrafast spin wave transport in both ferromagnetic and antiferromagnetic systems. [ABSTRACT FROM AUTHOR]

Two-dimensional magnets offer a new platform for exploring fundamental properties in van der Waals (vdW) heterostructures and their device applications. Here, we investigated heterostructure devices of itinerant metallic vdW ferromagnet Fe3GeTe2 (FGT) with monolayer chemical vapor deposited graphene. The anomalous Hall effect measurements of FGT Hall-bar devices exhibit robust ferromagnetism with strong perpendicular anisotropy at low temperatures. The electrical transport properties measured in FGT/graphene heterostructure devices exhibit a tunneling transport with weak temperature dependence. We assessed the suitability of such FGT/graphene heterostructures for spin injection and detection and investigated the presence of FGT on possible spin absorption and spin relaxation in the graphene channel. These findings will be useful for engineering spintronic devices based on vdW heterostructures. [ABSTRACT FROM AUTHOR]

It is well known that the Dresselhaus spin-orbit coupling (SOC) in semiconductor two dimensional electron gases (2DEGs) possesses both linear and cubic in momentum contributions. Nevertheless, the latter is usually neglected in most theoretical studies. However, recent Kerr rotation experiments have revealed a significant enhancement of the cubic Dresselhaus interaction by increasing the drift velocities in 2DEGs hosted in GaAs quantum wells. Here, we present a study of the optical spin Hall conductivity in 2DEGs under the simultaneous presence of Rashba and (linear plus cubic) Dresselhaus SOC. The work was done within the Kubo formalism in linear response. We show that the coexistence of the Rashba and cubic Dresselhaus SOC in 2DEGs promotes a strong anisotropy of the band spin splitting which in turn leads to a very characteristic frequency dependence of the spin Hall conductivity. We find that the spin Hall conductivity response could be very sensible to sizeable cubic-Dresselhaus coupling strength. This may be of relevance for the optical control of spin currents in 2DEGs with non-negligible cubic-Dresselhaus SOC. [ABSTRACT FROM AUTHOR]

The GEp-III and GEp-2γ experiments, carried out in Jefferson Lab's Hall C from 2007–2008, consisted of measurements of polarization transfer in elastic electron–proton scattering at momentum transfers of Q2=2.5,5.2,6.8, and 8.54 GeV 2. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio R=μpGEp∕GMp at large values of Q2 and to search for effects beyond the Born approximation in polarization transfer observables at Q2=2.5GeV2. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2γ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties.

The GEp-III and GEp-2γ experiments, carried out in Jefferson Lab's Hall C from 2007–2008, consisted of measurements of polarization transfer in elastic electron–proton scattering at momentum transfers of Q2=2.5,5.2,6.8, and 8.54 GeV 2. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio R=μpGEp∕GMp at large values of Q2 and to search for effects beyond the Born approximation in polarization transfer observables at Q2=2.5GeV2. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2γ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties.

We address spin transport in the easy-axis Heisenberg spin chain subject to different integrability-breaking perturbations. We find subdiffusive spin transport characterized by dynamical exponent z = 4 up to a timescale parametrically long in the anisotropy. In the limit of infinite anisotropy, transport is subdiffusive at all times; for finite anisotropy, one eventually recovers diffusion at late times but with a diffusion constant independent of the strength of the perturbation and solely fixed by the value of the anisotropy. We provide numerical evidence for these findings, and we show how they can be understood in terms of the dynamical screening of the relevant quasiparticle excitations and effective dynamical constraints. Our results show that the diffusion constant of near-integrable diffusive spin chains is generically not perturbative in the integrability-breaking strength. [ABSTRACT FROM AUTHOR]

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

We fabricated Fe3O4/alkyl-sulfonic acid and Fe3O4/alkyl-benzene sulfonic molecules hybrid nanoparticles using self-assembled monolayers to investigate the impact of benzene ring insertion on the spin tunneling through molecules. The results showed that benzene ring insertion decreased the tunnel barrier height, slightly tuned the magnetoresistance values, and enhanced the intramolecular spin diffusion length by ∼1.5 times. We proposed an extended model to explore the interfacial magnetic properties. The fitting results indicated that benzene ring insertion changed the magnetic properties of the shell layer. This work first demonstrated that benzene ring insertion enhanced the intramolecular spin diffusion length during the tunneling process. [ABSTRACT FROM AUTHOR]

We examine the coherent spin-dependent transport properties of the van der Waals (vdW) ferromagnet Fe 4 GeTe 2 using density functional theory combined with the nonequilibrium Green's function method. Our findings reveal that the conductance perpendicular to the layers is half-metallic, meaning that it is almost entirely spin-polarized. This property persists from the bulk to a single layer, even under significant bias voltages and with spin-orbit coupling. Additionally, using dynamical mean field theory for quantum transport, we demonstrate that electron correlations are important for magnetic properties but minimally impact the conductance, preserving almost perfect spin-polarization. Motivated by these results, we then study the tunnel magnetoresistance (TMR) in a magnetic tunnel junction consisting of two Fe 4 GeTe 2 layers with the vdW gap acting as an insulating barrier. We predict a TMR ratio of ∼500%, which can be further enhanced by increasing the number of Fe 4 GeTe 2 layers in the junction.

While the recent prediction and observation of magnetic skyrmions bears inspiring promise for next-generation spintronic devices, how to detect and track their position becomes an important issue. In this work, we investigate the spin transport in a two-dimensional magnetic nanoribbon with the Hall-bar geometry in the presence of Rashba spin-orbit coupling and magnetic skyrmions. We employ the Kwant tight-binding code to compute the Hall conductance and local spin-polarized current density. We consider two versions of the model: One with single skyrmion and one with two separate skyrmions. It is found that the size and position of the skyrmions strongly modulate the Hall conductance near the Hall-bar position. The geometry of the Hall bar also has a strong influence on the Hall conductance of the system. With the decreasing of the width of Hall leads, the peak of Hall conductance becomes sharper. We also show the spatial distribution of the spin-polarized current density around a skyrmion located at different positions. We extend this study toward two separate skyrmions, where the Hall conductance also reveals a sizable dependence on the position of the skyrmions and their distance. Our numerical analysis offers the possibility of electrically detecting the skyrmion position, which could have potential applications in ultrahigh-density storage design., (© 2024 IOP Publishing Ltd.)

In this paper, the effect of the direction of a magnetic field has been studied in leads (electrodes with limited width) on thermoelectric properties of Al 12 N 12 cage with and without considering inelastic electron–phonon interactions. Results showed that the biggest (smallest) value of total conductivity is observed in the case of the maximum value of elastic conductivity ( G σ , σ ′ M ) with respect to the direction of the magnetic field for antiparallel ( ↑ ↓ or ↓ ↑) , parallel configurations ( ↓ ↓ or ↑ ↑) for the left ( σ = ↑ ↓) and the right ( σ ′ = ↑ ↓) lead spins, i.e., G ↓ , ↑ M (G ↑ , ↑ M) . The maximum number of conduction heights was seen for σ = ↓ and σ ′ = ↑ . With respect to the direction of magnetic field in the leads, the maximum value of electronic thermal conductance (K e , σ σ ′ max) can be arranged in the following order: K e , ↓ ↑ max > K e , ↓ ↓ max > K e , ↑ ↓ max > K e , ↑ ↑ max . The direction of the magnetic field in the leads affects the numbers, height and width peaks and valleys of the first derivative of thermopower (TP). We observe the highest (deepest) peak (valley) when σ = ↑ and σ ′ = ↓ ( σ = ↑ and σ ′ = ↑ ). Also, the effect of temperature on current and tunnel magnetoresistance (TMR) was considered in this paper. [ABSTRACT FROM AUTHOR]

It is well known that the Dresselhaus spin-orbit coupling (SOC) in semiconductor two dimensional electron gases (2DEGs) possesses both linear and cubic in momentum contributions. Nevertheless, the latter is usually neglected in most theoretical studies. However, recent Kerr rotation experiments have revealed a significant enhancement of the cubic Dresselhaus interaction by increasing the drift velocities in 2DEGs hosted in GaAs quantum wells. Here, we present a study of the optical spin Hall conductivity in 2DEGs under the simultaneous presence of Rashba and (linear plus cubic) Dresselhaus SOC. The work was done within the Kubo formalism in linear response. We show that the coexistence of the Rashba and cubic Dresselhaus SOC in 2DEGs promotes a strong anisotropy of the band spin splitting which in turn leads to a very characteristic frequency dependence of the spin Hall conductivity. We find that the spin Hall conductivity response could be very sensible to sizeable cubic-Dresselhaus coupling strength. This may be of relevance for the optical control of spin currents in 2DEGs with non-negligible cubic-Dresselhaus SOC.

A mesoscopic multi-terminal superconducting Nb strip with a spin injection terminal has been developed. We investigate the influence of spin polarization on the relaxation process of the quasiparticle in the superconducting Nb. The position dependence of the nonlocal voltage provides the quasiparticle relaxation length. The relaxation length for the spin-polarized quasiparticle is found to show a 12.5% increase from that for the un-polarized quasiparticle. This demonstration opens a new avenue for utilization of the spin current in a superconducting device. [ABSTRACT FROM AUTHOR]

Antiferromagnets offer unique advantages in the development of spintronics because of the absence of stray field, insensitivity to external disturbances and the ultrafast terahertz eigenfrequency, advancing the development of devices toward small‐size and high‐speed. However, the ultralow read‐out signals of antiferromagnetic spintronics are notoriously smaller than their ferromagnetic counterpart, seriously hindering the development of antiferromagnets. Thus, experimental realization of large read‐out signals in antiferromagnets, especially in vertical devices, is intensely pursued. Here the antiferromagnetic magnon drag effect and a giant on–off ratio of ≈1000 are realized in a vertical sandwich structure of heavy metal/antiferromagnetic insulator/heavy metal (Pt/α‐Fe2O3/Pt). The read‐out signal can exist up to room temperature, and the detected signal owing to the transmission and blocking of magnon strongly relies on the relative orientation between spin polarization and Néel vector. Benefiting from the nonvolatile characteristic of Fe2O3, zero‐field vertical magnon transport is achieved. The giant on–off signals in vertical devices that can be tightly packed, can greatly promote the practical application of antiferromagnetic magnon devices toward smaller, faster, and lower energy consumption. [ABSTRACT FROM AUTHOR]

Abstract Spintronics is the most promising technology to develop alternative multi-functional, high-speed, low-energy electronic devices. Due to their unusual physical characteristics, emerging two-dimensional (2D) materials provide a new platform for exploring novel spintronic devices. Recently, 2D spintronics has made great progress in both theoretical and experimental researches. Here, the progress of 2D spintronics has been reviewed. In the last, the current challenges and future opportunities have been pointed out in this field.

The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe). The spin control is achieved by the application of the chirality-induced spin-dependent electron transfer effect and is probed by two different methods: spin-controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.

The transport properties of a molecular bio-electronic device based on the alanine amino-acid are investigated. The considered device consists of an alanine molecule as the central potential-dot coupled to two zigzag graphene nanoribbon (ZGNR) conducting electrodes. The current–voltage characteristics of this dual tunnelling molecular junction are studied at two different optimised compositions of the central molecule. The proposed amino-acid based structure utilises the tunnelling coupling similar to that of semiconducting single-electron transistors (SETs) to avoid complications due to the atomic interfaces. The current–voltage characteristics show polarity-dependent behaviour making the device feasible of being applied as a molecular rectifier. Negative differential resistance (NDR) along with tuneable peak-current position has been also observed in the current–voltage characteristics. The device is also capable of being applied as a switch controllable by the central molecule orientation. [ABSTRACT FROM AUTHOR]

Magnetic field dependence of the electronic spin polarization (P), polarization decay and spin oscillation in gallium arsenide quantum wells is investigated by spin-resolved photoluminescence measurements. In the presence of a magnetic field in the Voigt configuration, the spin-polarized electrons, generated by a circularly polarized light, are drifted by an electric field. The results show that P decays and oscillates with time as well as with the magnetic field. However, the electric field is found to play a vital role in spin dynamics and exchange coupling between the electron and hole spins in the wells. [ABSTRACT FROM AUTHOR]

Electrical generation and transduction of polarized electron spins in semiconductors (SCs) are of central interest in spintronics and quantum information science. While spin generation in SCs is frequently realized via electrical injection from a ferromagnet (FM), there are significant advantages in nonmagnetic pathways of creating spin polarization. One such pathway exploits the interplay of electron spin with chirality in electronic structures or real space. Here, utilizing chirality-induced spin selectivity (CISS), the efficient creation of spin accumulation in n-doped GaAs via electric current injection from a normal metal (Au) electrode through a self-assembled monolayer (SAM) of chiral molecules (α-helix l-polyalanine, AHPA-L), is demonstrated. The resulting spin polarization is detected as a Hanle effect in the n-GaAs, which is found to obey a distinct universal scaling with temperature and bias current consistent with chirality-induced spin accumulation. The experiment constitutes a definitive observation of CISS in a fully nonmagnetic device structure and demonstration of its ability to generate spin accumulation in a conventional SC. The results thus place key constraints on the physical mechanism of CISS and present a new scheme for magnet-free SC spintronics., (© 2024 Wiley‐VCH GmbH.)

Molecular semiconductor (MSC) is a promising candidate for spintronic applications benefiting from its long spin lifetime caused by light elemental-composition essence and thus weak spin-orbit coupling (SOC). According to current knowledge, the SOC effect, normally dominated by the elemental composition, is the main spin-relaxation causation in MSCs, and thus the molecular structure-induced SOC change is one of the most concerned issues. In theoretical study, molecular isomerism, a most prototype phenomenon, has long been considered to possess little difference on spin transport previously, since elemental compositions of isomers are totally the same. However, here in this study, quite different spin-transport performances are demonstrated in ITIC and its structural isomers BDTIC experimentally, for the first time, though the charge transport and molecular stacking of the two films are very similar. By further experiments of electron-paramagnetic resonance and density-functional-theory calculations, it is revealed that noncovalent-conformational locks (NCLs) formed in BDTIC can lead to enhancement of SOC and thus decrease the spin lifetime. Hence, this study suggests the influences from the structural-isomeric effect must be considered for developing highly efficient spin-transport MSCs, which also provides a reliable theoretical basis for solving the great challenge of quantificational measurement of NCLs in films in the future., (© 2024 Wiley‐VCH GmbH.)

A novel experimental optical method, based on photoluminescence and photo-induced resonant reflection techniques, is used to investigate the spin transport over long distances in a new, recently discovered collective state—magnetofermionic condensate. The given Bose–Einstein condensate exists in a purely fermionic system (ν = 2 quantum Hall insulator) due to the presence of a non-equilibrium ensemble of spin-triplet magnetoexcitons—composite bosons. It is found that the condensate can spread over macroscopically long distances of approximately 200 μm. The propagation velocity of long-lived spin excitations is measured to be 25 m/s. [ABSTRACT FROM AUTHOR]

Spin‐related phenomena in optoelectronic materials can revolutionize several technological applications in the areas of data processing and storage, quantum computing, lighting, energy harvesting, sensing, and healthcare. A fundamental boost to this promising field can be envisaged thanks to the use of two emerging materials, which have recently been receiving increasing scientific attention: organic semiconductors (OSCs) and halide perovskites (HPs). Here, the first progress in the resulting fields, organic‐ and perovskite‐based spintronics, is reviewed, which will enable the manipulation of spin, charges, and photons in spin/optoelectronic devices. A link between these two classes of materials is created by highlighting the pros and cons of each technology, and their potential applications in new multifunctional spintronic devices are discussed. Current challenges in the field are also outlined, and convenient approaches to overcome them are proposed. [ABSTRACT FROM AUTHOR]

The behavior of spin for incoherently hopping carriers is critical to understand in a variety of systems such as organic semiconductors, amorphous semiconductors, and muon-implanted materials. This work specifically examined the spin relaxation of hopping spin/charge carriers through a cubic lattice in the presence of varying degrees of energy disorder when the carrier spin is treated classically and random spin rotations are suffered during the hopping process (to mimic spin--orbit coupling effects) instead of during the wait time period (which would be more appropriate for hyperfine coupling). The problem was studied under a variety of different assumptions regarding the hopping rates and the random local fields. In some cases, analytic solutions for the spin relaxation rate were obtained. In all the models, we found that exponentially distributed energy disorder led to a drastic reduction in spin polarization losses that fell nonexponentially. [ABSTRACT FROM AUTHOR]

Herein, the spin‐dependent transport properties of a zigzag graphene nanoribbon (zGNR) with edges decorated with a fluoranthene group are studied. Atomically perfect zigzag edge, including phenyl‐edge functionalization, was synthesized by Ruffieux et al. in a bottom‐up chemical technique. By performing nearest‐neighbor tight‐binding model in combination with Landauer formalism and Green's function approach, as well as considering Coulomb electronic interaction computed both with density functional calculations and mean‐field approximation of the Hubbard model, the magnetic and spin‐resolved transmissions are studied. Both the model Hamiltonian and density functional theory (DFT) descriptions yield very similar results. Importantly, by generating a special supercell, three different antiferromagnetic alignments for phenyl‐edge zGNR have been calculated, which was not developed in previous studies. The results show that by adding pentagon rings on both sides of the zGNR, the conductance loses its step‐like behavior. Our structure of interest is a semiconductor with a transport gap of 0.56 eV. This kind of defective structure will enable the spin‐feature characteristic, such as spin filtering, and add the spin degree of freedom to graphene‐based logic devices. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the influence of topological magnon phases on quantum correlation and spin transport on layered ferrimagnets which is a fascinating topic in condensed matter physics. In the study of topological phases manipulated by an external magnetic field in layered ferrimagnets for the field applied along the easy axis, the system can transfer between a nodal-loop semimetal phase and a Weyl semimetal phase in perpendicularly and laterally magnetized geometries, respectively. The anisotropic nature of these materials means that the interactions between spins depend on their relative orientations in different directions. We analyze the effect of topological magnon bands induced by the coupling parameters on quantum correlation. The influence of these coupling parameters is also investigated on spin conductivity longitudinal and transversal as well. • The ground state properties are discussed. • Entanglement negativity as a function of the coupling parameters is analyzed. • Transport coefficients are calculated, [ABSTRACT FROM AUTHOR]

A Ti2NiAl inverse Heusler alloy based current-perpendicular-to-plane (CPP) spin valve (SV) with various kinds of atomic terminated interfaces has been designed to explore the potential application of Heusler alloys in spintronics devices. By performing first principles calculations combined with the nonequilibrium Green’s function, it is revealed that spin magnetic moments of interfacial atoms suffer a decrease, and the electronic structure shows that the TiNiB-terminated structure possesses the largest interface spin polarization of ≈55%. Our study on spin-transport properties indicates that the total transmission coefficient at the Fermi level mainly comes from the contribution from the spin up electrons, which are regarded as the majority of the spin electrons. When the two electrodes of the CPP-SV device are in parallel magnetization configuration, the interface containing Ti and Ni atoms possesses a higher spin up transmission coefficient than the interface containing Ti and Al atoms. The device with the TiNiB-terminated interface possesses the largest magnetoresistance ratio of 3.28 × 105, and it has great application potential in spintronics devices.

Graphene is considered as a promising material in spintronics due to its long spin relaxation time and long spin relaxation length. However, its spin transport properties have been studied at low carrier density only, beyond which much is still unknown. In this study, we explore the spin transport and spin precession properties in multilayer graphene at high carrier density using ionic liquid gating. We find that the spin relaxation time is directly proportional to the momentum relaxation time, indicating that the Elliott-Yafet mechanism still dominates the spin relaxation in multilayer graphene away from the charge neutrality point. Image 1 [ABSTRACT FROM AUTHOR]

The spin‐dependent transmission properties of (0,8) graphene nanoribbons (GNRs) with two substitutional Fe atom impurities (2Fe‐aGNRs) have been studied by the non‐equilibrium Green's function (NEGF) method in conjunction with density functional theory (DFT). Emphasis is placed on the spin‐filtering activity of current transmission elements derived from these structures. In particular, it is shown that devices based on 2Fe‐aGNR approach the limit of half‐metallicity, where the magnitude and the sign of the current spin polarization is controlled by the bias across the device as well as the spin state of the 2Fe subsystem. This effect is rationalized by electronic structure and partial‐density‐of‐states (PDOS) analysis of the transmission element. An occupied spin minority state, induced by the Fe‐atom moiety and close to the Fermi energy of 2Fe‐aGNR, accounts for the predominance of minority spin polarization. Comparison with nanosystems obtained from 2Fe‐aGNR, involving vacancies rather than impurities, or both types of defects, reveals that substantial degrees of current spin polarization prevail across a wide variety of device types. [ABSTRACT FROM AUTHOR]

π-Conjugated semiconductors, primarily composed of elements with low atomic number, are regarded as promising spin-transport materials due to the weak spin–orbit coupling interaction and hence long spin relaxation time. Moreover, a large number of additional functions of organic semiconductors (OSCs), such as the abundant photo-electric properties, flexibility, and tailorability, endow the organic spintronic devices more unique properties and functionalities. Particularly, the integration of the photo-electric functionality and excellent spin transport property of OSCs in a single spintronic device has even shown great potential for the realization of spin manipulation in OSCs. In this review, the application of OSCs in spintronic study will be succinctly discussed. As the most important and extensive application, the long-distance spin transport property of OSCs will be discussed first. Subsequently, several multifunctional spintronic devices based on OSCs will be summarized. After that, the organic-based magnets used for the electrodes of spintronic devices will be introduced. Finally, according to the latest progress, spin manipulation in OSCs via novel spintronic devices together with other prospects and challenges will be outlined.

Significant attention has been drawn to electronic transport in chiral materials coupled to ferromagnets in the chirality-induced spin selectivity (CISS) effect. A large magnetoresistance (MR) is usually observed, which is widely interpreted to originate from spin (dependent) transport. However, there are severe discrepancies between the experimental results and the theoretical interpretations, most notably the apparent failure of the Onsager reciprocity relations in the linear response regime. We provide an alternative mechanism for the two terminal MR in chiral systems coupled to a ferromagnet. For this, we point out that it was observed experimentally that the electrostatic contact potential of chiral materials on a ferromagnet depends on the magnetization direction and chirality. The mechanism that we provide causes the transport barrier to be modified by the magnetization direction, already in equilibrium, in the absence of a bias current. This strongly alters the charge transport through and over the barrier, not requiring spin transport. This provides a mechanism that allows the linear response resistance to be sensitive to the magnetization direction and also explains the failure of the Onsager reciprocity relations. We propose experimental configurations to confirm our alternative mechanism for MR.