Over the recent years, crossroads of magnetism and superconductivity led to the emerging field of superconducting spintronics. A cornerstone of this venture is the generation of equal-spin triplet Cooper pairs in superconductor-ferromagnet hybrids, enabling long-range spin-polarized supercurrents and magnetic control over superconducting quantum states for the development of energy-efficient cryogenic devices. Until now, nearly all superconducting spintronic devices have relied on direct interfaces between superconductors and ferromagnets, since it was believed that an insulating barrier would decouple spin and charge transport. This assumption, however, appears to be invalid when a thin spin- and orbit-filtering barrier couples epitaxial ferromagnet and the superconductor. Symmetry filtering plays a crucial role in enhancing giant tunneling magnetoresistance (TMR) by selectively allowing specific electronic states to tunnel through the barrier. Such a mechanism is key for high-performance spintronic devices like magnetic random access memories, magnetic sensors or spin-light emitting diodes. This manuscript provides a comprehensive review of superconducting spintronics driven by electron symmetry filtering and interfacial SOC. It emphasizes the critical role of a crystalline MgO barrier in selectively transmitting specific electronic states between V(100) and Fe(100). The manuscript also highlights how interfacial SOC enables symmetry mixing, allowing for the interaction between ferromagnetic and superconducting orderings though MgO(100). This mutual interaction, mediated by interfacial SOC, facilitates the conversion of spin-singlet to spin-triplet Cooper pairs. The work provides key insights into designing SOC based superconductor-ferromagnet hybrid structures for advanced superconducting spintronic functionalities.

Spin light-emitting diodes (spin-LEDs) convert carrier-spin polarization into photon circular polarization via electrical control of spin injection. They are key building blocks for spin-optoelectronic technologies, which hold great potential for a wide range of applications, such as optical communications, 3D displays and biomedical analysis. In this Review, we summarize the main developments in spin-LED injectors and emitters and identify strategies to overcome the key obstacles toward high, electrically controllable circular polarization. We first outline approaches to develop spin injectors that enable efficient electrical control of spin injection. We then present III–V semiconductors, 2D materials and hybrid perovskites as suitable material platforms for spin-photon interconversion. We argue that spin-injector engineering is necessary to achieve high circular polarization, eliminate external magnetic fields, and enable electrical switching of polarization helicity. Finally, we highlight future research directions aimed at high-speed polarization modulation, spin-laser operation and spin-based single-photon sources for quantum optics. Spin light-emitting diodes convert electrically injected carrier spin into circularly polarized light. This Review highlights advances in spin injectors and emitter materials, and strategies for high electrically controlled polarization without magnetic fields for circular polarization-based spin-optoelectronic applications like optical communications.

GaN-based spin light-emitting diodes (spin-LEDs) are attractive for realizing room-temperature spin-controlled light emission in efficient, color-tunable devices. In this work, we demonstrate spin injection in a GaN spin-LED fabricated on a Si substrate using wafer-bonding technology. An inverted n-i-p LED structure with n-type GaN on top facilitates the injection of spin-polarized electrons from a ferromagnetic Au/Co/MgO spin-injector layer grown by molecular beam epitaxy. At room temperature, an electroluminescence circular polarization of approximately 8% is measured under an applied 1 T out-of-plane magnetic field in a surface-emitting geometry. After considering contributions from the Zeeman effect and magnetic circular dichroism, about 6% circular polarization is attributed to the pure spin injection into GaN. This work is focused on the detailed structural and interface characterization of the spin-LED and allows to understand its spin and optoelectronic properties. These results highlight the potential of GaN-based spin-optoelectronic devices compatible with Si platforms.

Lateral heterostructures are important for exploring exotic physics, developing new devices and achieving device miniaturization1-8. Endo-epitaxial growth occurring in patterned templates presents a promising strategy to realize extensive patterned areas in heterostructures, as recently demonstrated with two-dimensional (2D) covalent materials9-13. However, the conventional lithography and etching processes used to prepare patterned templates are too aggressive for 2D lead halide perovskites, owing to their inherently soft and unstable ionic lattice14-16. Here we create square holes of controllable size within 2D lead halide perovskites, enabling the fabrication of continuous lateral heterostructures over large areas. We demonstrate that the square holes form through spontaneous etching, a process initiated by internal strain and stabilized along the [100]/[010] crystallographic direction. Furthermore, the size of the square holes can be controlled by adjusting the etching time and temperature. Moreover, by incorporating a rapid solvent evaporation growth technique, the edges of the square holes act as templates for epitaxial growth of another type of perovskite, incorporating different halide or metal ions. Finally, we realized a series of mosaic lateral heterostructures that can emit various colours for light-emitting devices. This synthesis of diverse 2D perovskite mosaic lateral heterostructures provides valuable insights into the structural characteristics of perovskites and offers a versatile material platform for the development of complex integrated emitting devices.

The time dynamics of spin-injected, electrically contacted quantum dots were investigated with a focus on the time evolution of photon statistics. Photon statistics can provide insights into whether the device functions as an effective single-photon emitter or exhibits higher-order emissions. Through these investigations, we found that the shape of the electrical excitation pulse has a direct impact on photon statistics. Specifically, the rising edge of the pulse corresponds to a significantly higher number of higher-order photon states, which decay much faster than single photons associated with the falling edge of the electrical pulse. This relationship implies that the pulse shape can be tailored to optimize the device as either a better single-photon source or a generator of higher-order photon states, with potential applications in creating deterministic higher-order photon Fock states. The ability to easily modify the pulse shape is a unique feature of electrically excited quantum dots.

Memristors are emerging as key electronic components that retain resistance states without power. Their nonvolatile nature and ability to mimic synaptic behavior make them ideal for next-generation memory technologies and neuromorphic computing systems inspired by the human brain. In this study, we present a novel organic spintronic memristor based on a La0.67Sr0.33MnO3 (LSMO)/poly(vinylidene fluoride) (PVDF)/Co heterostructure exhibiting biologically inspired synaptic behavior. Driven by fluorine atom migration within the PVDF layer, the device demonstrates both long-term depression and long-term potentiation under controlled electrical polarization. Distinctively, the resistance states can also be modulated by an external magnetic field via the tunneling magnetoresistance effect, introducing a nonelectrical means of tuning synaptic plasticity. This magnetic control mechanism enables multistate modulation without compromising device performance or endurance. Furthermore, convolutional neural network simulations incorporating this magnetic tuning capability reveal enhanced pattern recognition accuracy and improved training stability, especially at high learning rates. These findings underscore the potential of organic spintronic memristors as high-performance, low-power neuromorphic elements, particularly suited for applications in flexible and wearable electronics.

Spin light-emitting diodes (spin-LEDs), which converts carrier spin information to optical polarization, are important for modern display application and future technologies including spin-based electronic circuits and quantum information science. Spin-LEDs operate through spin-polarized carrier injection, directly converting spin angular momentum into photon helicity. Recent advances in materials and mechanism understanding have significantly improved spin injection efficiency and device performance. This review discusses the fundamental principles and operation mechanisms of spin-LEDs, where we examine conventional spin injection approaches and their constraints. We then highlight the emerging role of chiral-induced spin selectivity (CISS) in spin-LEDs, exploring how this novel mechanism could enhance circularly polarized electroluminescence efficiency and enable new device architectures. Finally, we provide perspectives on current challenges.

Shaping the electrical excitation pulse of spin injected quantum dots reveals a correlation between the time dynamics of higher-order photon emission and the pulse shape. This opens new pathways for integrated quantum light sources.

By measuring the shot noise, a consequence of charge quantization, in super-conductor/insulator/ferromagnet (V/MgO/Fe) junctions, we discover a giant increase, orders of magnitude larger than expected. The origin of this giant noise is a peculiar realization of a superconducting proximity effect, where a simple superconductor influences its neighbors. Our measurements reveal largely unexplored implications of orbital-symmetry-controlled proximity effects. The importance of orbital symmetries and the accompanying spin-orbit coupling is manifested by an unexpected emergence of another superconducting region, strikingly different from the parent superconductor. Unlike vanadium's common spin-singlet superconductivity, the broken inversion symmetry in V/MgO/Fe junctions and the resulting interfacial spin-orbit coupling lead to the formation of spin-triplet superconductivity across the ferromagnetic iron. Here, we show that the enhanced shot noise, known from Josephson junctions with two superconductors, is measured even in a single superconductor. This discovery motivates revisiting how the spin-orbit coupling and superconducting proximity effects can transform many materials.

Recent studies have revealed magnetically controllable thermoelectric effects in superconductor/ferromagnet (S/F) structures. A tunable cryogenic thermoelectric generator needs not only a high conversion factor between electricity and heat, but also a large change in the thermoelectric output when switching the magnetic state of the device. However, the reported modifications in thermoelectric power are either minimal, involve superconductors with relatively low critical temperatures (below 1 K), or do not utilize commercially available spintronic materials. Here, we experimentally measure and numerically model thermoelectric effects in fully epitaxial ferromagnet/superconductor/ferromagnet (F/S/F) junctions based on commercially available easily grown materials, as well as their dependence on the magnetic configuration of the ferromagnetic (F) electrodes. We observe sizeable Seebeck coefficients for the parallel alignment of the F electrodes, reaching values of about 100 μV/K. Importantly, we find a decrease of the thermoelectric signal of more than an order of magnitude when switching from a parallel to an antiparallel configuration, constituting a large thermoelectric spin-valve effect. Theoretical modeling based on a self-consistent nonequilibrium Keldysh-Usadel Green’s function theory, combined with micromagnetic simulations, qualitatively reproduce the experimental findings. The thermoelectric effect is optimized when there is a large spin-dependent electron-hole asymmetry in the superconductor combined with spin-dependent transmission through the interfaces. These findings pave the way for the development of efficient and versatile cryogenic thermoelectric heat engines.

Quantum well (QW) states formed in a double-barrier magnetic tunnel junction (DMTJ) enable the coherent resonant tunneling of electrons. This phenomenon is significant for both the fundamental understanding of quantum transport and the development of advanced functionalities in spintronic devices. Careful engineering of the structural and chemical disorders at the QW/barrier interface is essential to maintain strong electron phase coherence, thereby ensuring reliable conductance oscillations in DMTJ. In this study, we systematically investigate the influence of interfacial disorders and band structure on QW-induced conductance oscillations in epitaxial Fe/MgAlOx/Fe (QW)/MgAlOx/Co/Fe DMTJs grown by molecular beam epitaxy. It is found that the amplitude of QW oscillations is reduced to one-third due to chemical disorders caused by the incorporation of 2-4 monolayers of Co at the Fe (QW)/MgAlOx interface. In contrast, structural disorder induced by the incorporation of a single Fe monolayer completely suppresses the oscillations. In addition, the QW oscillation depends on the available majority Delta(1) states of the injecting electrons at the Fermi level (E-F) with k(//) = 0 from the upper electrode. Replacing the Fe upper electrode with Fe4N, which lacks a majority of Delta(1) states at E-F, significantly reduces the oscillation amplitude. Instead, using the bcc Co upper electrode, which possesses majority Delta(1) states, results in no change in QW oscillation. Our findings highlight the critical role of interfacial disorder and band structure in QW-induced conductance oscillations, advancing the development of spin-dependent quantum resonant tunneling applications.

The low -energy electronic spin precession is measured in the molecular field of a CoAl thin film. Designed to have a low Curie temperature, the variation of the CoAl molecular field results in an electronic spin precession angle that varies with temperature. The behavior is observed for injection energies between 0.9 and 1.2 eV and the results are explained on the basis of an exchange field varying with temperature.

Over the past decade, it has been proposed theoretically and confirmed experimentally that long-range spin-triplet (LRT) superconductivity can be generated in superconductor/ferromagnet hybrids either by the presence of spin textures (ST-LRT) or owing to spin-orbit coupling (SOC-LRT). Nevertheless, there has been no theoretical or experimental investigation to date suggesting that both contributions could simultaneously exist within an experimental system. To disentangle these contributions, we present a comprehensive study of superconducting quasiparticle interference effects taking place inside a ferromagnetic layer interfacing a superconductor, through the investigation of above-gap conductance anomalies (CAs) related to MacMillan- Rowell resonances. The bias dependence of the CAs has been studied under a wide range of in-plane (IP) and out-of-plane (OOP) magnetic fields in two types of epitaxial, V/MgO/Fe-based ferromagnet-superconductor junctions with interfacial spin-orbit coupling. We observe an anisotropy of the CA amplitude under small IP and OOP magnetic fields while remaining weakly affected by high fields, and implement micromagnetic simulations to help us distinguish between the ST-LRT and SOC-LRT contributions. Our findings suggest that further exploration of Fabry-P & eacute;rot-type interference effects in electron transport could yield valuable insights into the hybridization between superconductors and ferromagnets induced by spin-orbit coupling and spin textures.

Controlling the intensity of emitted light and charge current is the basis of transferring and processing information 1 . By contrast, robust information storage and magnetic random-access memories are implemented using the spin of the carrier and the associated magnetization in ferromagnets 2 . The missing link between the respective disciplines of photonics, electronics and spintronics is to modulate the circular polarization of the emitted light, rather than its intensity, by electrically controlled magnetization. Here we demonstrate that this missing link is established at room temperature and zero applied magnetic field in light-emitting diodes 2 – 7 , through the transfer of angular momentum between photons, electrons and ferromagnets. With spin–orbit torque 8 – 11 , a charge current generates also a spin current to electrically switch the magnetization. This switching determines the spin orientation of injected carriers into semiconductors, in which the transfer of angular momentum from the electron spin to photon controls the circular polarization of the emitted light 2 . The spin–photon conversion with the nonvolatile control of magnetization opens paths to seamlessly integrate information transfer, processing and storage. Our results provide substantial advances towards electrically controlled ultrafast modulation of circular polarization and spin injection with magnetization dynamics for the next-generation information and communication technology 12 , including space–light data transfer. The same operating principle in scaled-down structures or using two-dimensional materials will enable transformative opportunities for quantum information processing with spin-controlled single-photon sources, as well as for implementing spin-dependent time-resolved spectroscopies.

Integrating tunneling magnetoresistance (TMR) effect in memristors is a long-term aspiration because it allows to realize multifunctional devices, such as multi-state memory and tunable plasticity for synaptic function. However, the reported TMR in different multiferroic tunnel junctions is limited to 100%. This work demonstrates a giant TMR of -266% in La0.6Sr0.4MnO3(LSMO)/poly(vinylidene fluoride)(PVDF)/Co memristor with thin organic barrier. Different from the ferroelectricity-based memristors, this work discovers that the voltage-driven florine (F) motion in the junction generates a huge reversible resistivity change up to 106% with nanosecond (ns) timescale. Removing F from PVDF layer suppresses the dipole field in the tunneling barrier, thereby significantly enhances the TMR. Furthermore, the TMR can be tuned by different polarizing voltage due to the strong modification of spin-polarization at the LSMO/PVDF interface upon F doping. Combining of high TMR in the organic memristor paves the way to develop high-performance multifunctional devices for storage and neuromorphic applications.

We investigate the growth of Au/FexNy/MgO trilayers on GaAs(001) substrates by plasma-assisted molecular beam epitaxy. The optimization of the growth conditions made it possible to obtain the compound of stoichiometric Fe4N. Microstructural studies show that Fe4N forms 3D islands at the initial stages of growth. As the Fe4N thickness increases, a columnar growth sets in leading to a strong texturing and to the formation of grains having the same crystallographic orientation. The growth is epitaxial with the relationship GaAs (001) [110]//MgO (001) [110]//Fe4N (001) [110]//Au (012) [0-32]. A chemical analysis at the nanoscale reveals that the interfaces are rather sharp with a limited interdiffusion. Magnetic characterizations show that a trilayer containing a 1-nm-thick Fe4N layer is already ferromagnetic. The easy magnetization axis is in-plane independent of the Fe4N layer thickness (from 1 to 6 nm). This study shows the potential to use Fe4N as a spin injector for spin-optoelectronic applications.