Spin-Orbit-Torque-Driven Two-Terminal Giant Magnetoresistance Memristive Devices for In-Memory Computing.

The rising complexity of artificial intelligence and data-intensive applications drives the demand for memristive devices to support high-performance and scalable processing-in-memory (PIM) architectures. While three- and four-terminal spintronic PIM solutions show promise, they face scalability challenges due to large footprints. This study demonstrates a two-terminal spin-orbit torque (SOT)-driven giant magnetoresistance (GMR) memristive device utilizing a Pt/Co/Cu/CoTb stack, integrating data storage and logic functions within a single unit.

Topological transformation of synthetic ferromagnetic skyrmions: thermal assisted switching of helicity by spin-orbit torque.

This study demonstrates the controllable switching of skyrmion helicity using spin-orbit torque, enhanced by thermal effects. Electric current pulses applied to a [Pt/Co]/Ru/[Co/Pt] multilayer stripe drive skyrmions in a direction opposite to the current flow. Continuous pulsing results in an unexpected reversal of skyrmion motion.

Energy-efficient superparamagnetic Ising machine and its application to traveling salesman problems.

The growth of artificial intelligence leads to a computational burden in solving non-deterministic polynomial-time (NP)-hard problems. The Ising computer, which aims to solve NP-hard problems faces challenges such as high power consumption and limited scalability. Here, we experimentally present an Ising annealing computer based on 80 superparamagnetic tunnel junctions (SMTJs) with all-to-all connections, which solves a 70-city traveling salesman problem (TSP, 4761-node Ising problem).

Spin-based magnetic random-access memory for high-performance computing.

Spin-based memory technology is now available as embedded magnetic random access memory (eMRAM) for fast, high-density and non-volatile memory products, which can significantly boost computing performance and ignite the development of new computing architectures.

Field-Free Spin-Orbit Torque Driven Switching of Perpendicular Magnetic Tunnel Junction through Bending Current.

Current-induced spin-orbit torques (SOTs) enable fast and efficient manipulation of the magnetic state of magnetic tunnel junctions (MTJs), making them attractive for memory, in-memory computing, and logic applications. However, the requirement of the external magnetic field to achieve deterministic switching in perpendicularly magnetized SOT-MTJs limits its implementation for practical applications. Here, we introduce a field-free switching (FFS) solution for the SOT-MTJ device by shaping the SOT channel to create a "bend" in the SOT current.

Bloch Chirality Induced by an Interlayer Dzyaloshinskii-Moriya Interaction in Ferromagnetic Multilayers.

Chiral spin textures stabilized by the interfacial Dzyaloshinkii-Moriya interaction, such as skyrmions and homochiral domain walls, have been shown to exhibit qualities that make them attractive for their incorporation in a variety of spintronic devices. However, for thicker multilayer films, mixed textures occur in which an achiral Bloch component coexists with a chiral Néel component of the domain wall to reduce the demagnetization field at the film surface. We show that an interlayer Dzyaloshinkii-Moriya interaction can break the degeneracy between Bloch chiralities.

Spin-Orbit Torque Magnetization Switching in MoTe /Permalloy Heterostructures.

The ability to switch magnetic elements by spin-orbit-induced torques has recently attracted much attention for a path toward high-performance, nonvolatile memories with low power consumption. Realizing efficient spin-orbit-based switching requires the harnessing of both new materials and novel physics to obtain high charge-to-spin conversion efficiencies, thus making the choice of spin source crucial. Here, the observation of spin-orbit torque switching in bilayers consisting of a semimetallic film of 1T'-MoTe adjacent to permalloy is reported.

Anisotropic Picosecond Spin-Photocurrent from Weyl Semimetal WTe.

The generation and detection of ultrafast spin current, preferably reaching a frequency up to terahertz, is the core of spintronics. Studies have shown that the Weyl semimetal WTe is of great potential in generating spin currents. However, the prior studies have been limited to the static measurements with the in-plane spin orientation.

Magnetization switching by magnon-mediated spin torque through an antiferromagnetic insulator.

Widespread applications of magnetic devices require an efficient means to manipulate the local magnetization. One mechanism is the electrical spin-transfer torque associated with electron-mediated spin currents; however, this suffers from substantial energy dissipation caused by Joule heating. We experimentally demonstrated an alternative approach based on magnon currents and achieved magnon-torque-induced magnetization switching in BiSe/antiferromagnetic insulator NiO/ferromagnet devices at room temperature.

All-electric magnetization switching and Dzyaloshinskii-Moriya interaction in WTe/ferromagnet heterostructures.

All-electric magnetization manipulation at low power is a prerequisite for a wide adoption of spintronic devices. Materials such as heavy metals or topological insulators provide good charge-to-spin conversion efficiencies. They enable magnetization switching in heterostructures with either metallic ferromagnets or with magnetic insulators.

Nonlinear magnetotransport shaped by Fermi surface topology and convexity.

The nature of Fermi surface defines the physical properties of conductors and many physical phenomena can be traced to its shape. Although the recent discovery of a current-dependent nonlinear magnetoresistance in spin-polarized non-magnetic materials has attracted considerable attention in spintronics, correlations between this phenomenon and the underlying fermiology remain unexplored. Here, we report the observation of nonlinear magnetoresistance at room temperature in a semimetal WTe, with an interesting temperature-driven inversion.

Anomalous Photothermoelectric Transport Due to Anisotropic Energy Dispersion in WTe.

Band structures are vital in determining the electronic properties of materials. Recently, the two-dimensional (2D) semimetallic transition metal tellurides (WTe and MoTe) have sparked broad research interest because of their elliptical or open Fermi surface, making distinct from the conventional 2D materials. In this study, we demonstrate a centrosymmetric photothermoelectric voltage distribution in WTe nanoflakes, which has not been observed in common 2D materials such as graphene and MoS.

Electric-field control of spin accumulation direction for spin-orbit torques.

Electric field is an energy-efficient tool that can be leveraged to control spin-orbit torques (SOTs). Although the amount of current-induced spin accumulation in a heavy metal (HM)/ferromagnet (FM) heterostructure can be regulated to a certain degree using an electric field in various materials, the control of its direction has remained elusive so far. Here, we report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device.

Observation of Out-of-Plane Spin Texture in a SrTiO_{3}(111) Two-Dimensional Electron Gas.

We explore the second order bilinear magnetoelectric resistance (BMER) effect in the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO_{3}(111) surface. We find evidence of a spin-split band structure with the archetypal spin-momentum locking of the Rashba effect for the in-plane component. Under an out-of-plane magnetic field, we find a BMER signal that breaks the sixfold symmetry of the electronic dispersion, which is a fingerprint for the presence of a momentum-dependent out-of-plane spin component.

Field-Free Spin-Orbit Torque Switching from Geometrical Domain-Wall Pinning.

Spin-orbit torques, which utilize spin currents arising from the spin-orbit coupling, offer a novel method for the electrical switching of the magnetization with perpendicular anisotropy. However, the necessity of an external magnetic field to achieve deterministic switching is an obstacle for realizing practical spin-orbit torque devices with all-electric operation. Here, we report field-free spin-orbit torque switching by exploiting the domain-wall motion in an anti-notched microwire with perpendicular anisotropy, which exhibits multidomain states stabilized by the domain-wall surface tension.

Room-Temperature Nanoseconds Spin Relaxation in WTe and MoTe Thin Films.

The Weyl semimetal WTe and MoTe show great potential in generating large spin currents since they possess topologically protected spin-polarized states and can carry a very large current density. In addition, the intrinsic non-centrosymmetry of WTe and MoTe endows with a unique property of crystal symmetry-controlled spin-orbit torques. An important question to be answered for developing spintronic devices is how spins relax in WTe and MoTe.

Nonvolatile infrared memory in MoS/PbS van der Waals heterostructures.

Optoelectronic devices for information storage and processing are at the heart of optical communication technology due to their significant applications in optical recording and computing. The infrared radiations of 850, 1310, and 1550 nm with low energy dissipation in optical fibers are typical optical communication wavebands. However, optoelectronic devices that could convert and store the infrared data into electrical signals, thereby enabling optical data communications, have not yet been realized.

Electric field control of deterministic current-induced magnetization switching in a hybrid ferromagnetic/ferroelectric structure.

All-electrical and programmable manipulations of ferromagnetic bits are highly pursued for the aim of high integration and low energy consumption in modern information technology. Methods based on the spin-orbit torque switching in heavy metal/ferromagnet structures have been proposed with magnetic field, and are heading toward deterministic switching without external magnetic field. Here we demonstrate that an in-plane effective magnetic field can be induced by an electric field without breaking the symmetry of the structure of the thin film, and realize the deterministic magnetization switching in a hybrid ferromagnetic/ferroelectric structure with Pt/Co/Ni/Co/Pt layers on PMN-PT substrate.

Piezo Voltage Controlled Planar Hall Effect Devices.

The electrical control of the magnetization switching in ferromagnets is highly desired for future spintronic applications. Here we report on hybrid piezoelectric (PZT)/ferromagnetic (Co2FeAl) devices in which the planar Hall voltage in the ferromagnetic layer is tuned solely by piezo voltages. The change of planar Hall voltage is associated with magnetization switching through 90° in the plane under piezo voltages.

Spin-orbit torque in Pt/CoNiCo/Pt symmetric devices.

Current induced magnetization switching by spin-orbit torques offers an energy-efficient means of writing information in heavy metal/ferromagnet (FM) multilayer systems. The relative contributions of field-like torques and damping-like torques to the magnetization switching induced by the electrical current are still under debate. Here, we describe a device based on a symmetric Pt/FM/Pt structure, in which we demonstrate a strong damping-like torque from the spin Hall effect and unmeasurable field-like torque from Rashba effect.

Rational Design of Ultralarge Pb1-x Snx Te Nanoplates for Exploring Crystalline Symmetry-Protected Topological Transport.

Ultralarge topological crystalline insulator Pb1-x Snx Te nanoplates are developed by controlling substrate surface chemical properties in a cost-efficient chemical vapor deposition (CVD) process. Dominant topological surface transport is demonstrated by a gate-voltage-controlled weak (anti)localization effect, indicating the potential application of these nanoplates to low-dissipation topological transistors.

Strong enhancement of photoresponsivity with shrinking the electrodes spacing in few layer GaSe photodetectors.

A critical challenge for the integration of optoelectronics is that photodetectors have relatively poor sensitivities at the nanometer scale. Generally, a large electrodes spacing in photodetectors is required to absorb sufficient light to maintain high photoresponsivity and reduce the dark current. However, this will limit the optoelectronic integration density.