Explore the vast range of titles available.

Two-dimensional (2D) crystals offer a unique platform due to their remarkable and contrasting spintronic properties, such as weak spin–orbit coupling (SOC) in graphene and strong SOC in molybdenum disulfide (MoS 2 ). Here we combine graphene and MoS 2 in a van der Waals heterostructure (vdWh) to demonstrate the electric gate control of the spin current and spin lifetime at room temperature. By performing non-local spin valve and Hanle measurements, we unambiguously prove the gate tunability of the spin current and spin lifetime in graphene/MoS 2 vdWhs at 300 K. This unprecedented control over the spin parameters by orders of magnitude stems from the gate tuning of the Schottky barrier at the MoS 2 /graphene interface and MoS 2 channel conductivity leading to spin dephasing in high-SOC material. Our findings demonstrate an all-electrical spintronic device at room temperature with the creation, transport and control of the spin in 2D materials heterostructures, which can be key building blocks in future device architectures. Two-dimensional materials are unique to build heterostructures with contrasting spintronic properties. Here, Dankert and Dash utilize a van der Waals heterostructure with graphene and MoS 2 to demonstrate an all-electrical device for creation, transport and control of the spin current up to room temperature.

Unique electronic spin textures in topological states of matter are promising for emerging spin-orbit driven memory and logic technologies. However, there are several challenges related to the enhancement of their performance, electrical gate-tunability, interference from trivial bulk states, and heterostructure interfaces. We address these challenges by integrating two-dimensional graphene with a three-dimensional topological insulator (TI) in van der Waals heterostructures to take advantage of their remarkable spintronic properties and engineer proximity-induced spin-charge conversion phenomena. In these heterostructures, we experimentally demonstrate a gate-tunable spin-galvanic effect (SGE) at room temperature, allowing for efficient conversion of a non-equilibrium spin polarization into a transverse charge current. Systematic measurements of SGE in various device geometries via a spin switch, spin precession, and magnetization rotation experiments establish the robustness of spin-charge conversion in the Gr-TI heterostructures. Importantly, using a gate voltage, we reveal a strong electric field tunability of both amplitude and sign of the spin-galvanic signal. These findings provide an efficient route for realizing all-electrical and gate-tunable spin-orbit technology using TIs and graphene in heterostructures, which can enhance the performance and reduce power dissipation in spintronic circuits. The spin-galvanic effect allows for the conversion of non-equilibrium spin density into a charge current. Here, by combining graphene in a van de Waals heterostructure with a topological insulator, the authors demonstrate a large, gate-tunable spin-galvanic effect.

Transition metal dichalcogenide (TMD) heterobilayers provide a versatile platform to explore unique excitonic physics via the properties of the constituent TMDs and external stimuli. Interlayer excitons (IXs) can form in TMD heterobilayers as delocalized or localized states. However, the localization of IX in different types of potential traps, the emergence of biexcitons in the high-excitation regime, and the impact of potential traps on biexciton formation have remained elusive. In our work, we observe two types of potential traps in a MoSe 2 /WSe 2 heterobilayer, which result in significantly different emission behavior of IXs at different temperatures. We identify the origin of these traps as localized defect states and the moiré potential of the TMD heterobilayer. Furthermore, with strong excitation intensity, a superlinear emission behavior indicates the emergence of interlayer biexcitons, whose formation peaks at a specific temperature. Our work elucidates the different excitation and temperature regimes required for the formation of both localized and delocalized IX and biexcitons and, thus, contributes to a better understanding and application of the rich exciton physics in TMD heterostructures. The authors investigate the optical response of marginally twisted MoSe 2 /WSe 2 heterobilayers and identify two types of trapped excitons depending on laser excitation power and temperature: excitons trapped in shallow defects and excitons trapped in the moire potential. At strong excitation powers, interlayer biexcitons are identified.

The unique electronic properties of topological quantum materials, such as protected surface states and exotic quasiparticles, can provide an out-of-plane spin-polarized current needed for external field-free magnetization switching of magnets with perpendicular magnetic anisotropy. Conventional spin–orbit torque (SOT) materials provide only an in-plane spin-polarized current, and recently explored materials with lower crystal symmetries provide very low out-of-plane spin-polarized current components, which are not suitable for energy-efficient SOT applications. Here, we demonstrate a large out-of-plane damping-like SOT at room temperature using the topological Weyl semimetal candidate TaIrTe 4 with a lower crystal symmetry. We performed spin–torque ferromagnetic resonance (STFMR) and second harmonic Hall measurements on devices based on TaIrTe 4 /Ni 80 Fe 20 heterostructures and observed a large out-of-plane damping-like SOT efficiency. The out-of-plane spin Hall conductivity is estimated to be (4.05 ± 0.23)×10 4 (ℏ ⁄ 2 e ) (Ωm) −1 , which is an order of magnitude higher than the reported values in other materials. Topological semimetals offer the potential for new-generation spintronic devices. Here, the authors demonstrate a large out-of-plane damping-like spin–orbit torque efficiency in a heterostructure based on the Weyl semimetal TaIrTe 4 .

Silicon-based spintronics In spintronics, the electron spin degree of freedom replaces the electron charge, the basic unit of conventional electronics, as the information carrier in future spin-based electronic, data storage and computing technologies. Motivated by the prevalence of silicon in present-day electronics, efforts have been made to realize silicon-based spintronics devices, but so far, successful control of the charge carriers' spin in such devices has been limited to low temperatures and to one type of carrier (electrons) only, thus limiting their technological potential. Now a team at the University of Twente has produced a silicon-based three-terminal device in which they demonstrate the successful room-temperature injection, manipulation and detection of spin polarization of both electrons and their positively charged counterparts known as 'holes'. Spintronics aims to represent digital information using spin orientation rather than electron charge, ideally at room temperature and in silicon, which is already ubiquitous in present-day technologies. But so far successful control of spin has only been achieved for electrons and at low temperatures. Now room-temperature injection, manipulation and detection of spin polarization of both electrons and their positively charged counterparts (holes) brings the realization of silicon spintronic devices closer. The control and manipulation of the electron spin in semiconductors is central to spintronics 1 , 2 , which aims to represent digital information using spin orientation rather than electron charge. Such spin-based technologies may have a profound impact on nanoelectronics, data storage, and logic and computer architectures. Recently it has become possible to induce and detect spin polarization in otherwise non-magnetic semiconductors (gallium arsenide and silicon) using all-electrical structures 3 , 4 , 5 , 6 , 7 , 8 , 9 , but so far only at temperatures below 150 K and in n-type materials, which limits further development. Here we demonstrate room-temperature electrical injection of spin polarization into n-type and p-type silicon from a ferromagnetic tunnel contact, spin manipulation using the Hanle effect and the electrical detection of the induced spin accumulation. A spin splitting as large as 2.9 meV is created in n-type silicon, corresponding to an electron spin polarization of 4.6%. The extracted spin lifetime is greater than 140 ps for conduction electrons in heavily doped n-type silicon at 300 K and greater than 270 ps for holes in heavily doped p-type silicon at the same temperature. The spin diffusion length is greater than 230 nm for electrons and 310 nm for holes in the corresponding materials. These results open the way to the implementation of spin functionality in complementary silicon devices and electronic circuits operating at ambient temperature, and to the exploration of their prospects and the fundamental rules that govern their behaviour.

Two dimensional atomically thin crystals of graphene and its insulating isomorph hexagonal boron nitride (h-BN) are promising materials for spintronic applications. While graphene is an ideal medium for long distance spin transport, h-BN is an insulating tunnel barrier that has potential for efficient spin polarized tunneling from ferromagnets. Here, we demonstrate the spin filtering effect in cobalt|few layer h-BN|graphene junctions leading to a large negative spin polarization in graphene at room temperature. Through nonlocal pure spin transport and Hanle precession measurements performed on devices with different interface barrier conditions, we associate the negative spin polarization with high resistance few layer h-BN|ferromagnet contacts. Detailed bias and gate dependent measurements reinforce the robustness of the effect in our devices. These spintronic effects in two-dimensional van der Waals heterostructures hold promise for future spin based logic and memory applications.

Two-dimensional quantum material heterostructures can offer a promising platform for energy-efficient non-volatile spin-based technologies. However, spin dynamics experiments to understand the basic spin-orbit torque phenomena are so far lacking. Here, we demonstrate unconventional out-of-plane magnetization dynamics, and energy-efficient and field-free spin-orbit torque switching in a van der Waals heterostructure comprising out-of-plane magnet Fe 3 GaTe 2 and topological Weyl semimetal TaIrTe 4 . We measured non-linear second harmonic Hall signal in TaIrTe 4 /Fe 3 GaTe 2 devices to evaluate the magnetization dynamics, which is characterized by large and tunable out-of-plane damping-like torque. Energy-efficient and deterministic field-free SOT magnetization switching is achieved at room temperature with a very low current density. First-principles calculations unveil the origin of the unconventional charge-spin conversion phenomena, considering the crystal symmetry and electronic structure of TaIrTe 4 . These results establish that van der Waals heterostructures provide a promising route to energy-efficient, field-free, and tunable spintronic devices. Weyl semimetals with low crystal symmetry, such as TaIrTe4, are known to host large unconventional spin-orbit torques. Here, Pandey et al combine TaIrTe4 with the van der Waals ferromagnet, Fe3GaTe2, and achieve room temperature field-free magnetization switching with an extremely low critical current density.

The two-dimensional atomically thin insulator hexagonal boron nitride （h-BN） constitutes a new paradigm in tunnel based devices. A large band gap, along with its atomically flat nature without dangling bonds or interface trap states, makes it an ideal candidate for tunnel spin transport in spintronic devices. Here, we demonstrate the tunneling of spin-polarized electrons through large area monolayer h-BN prepared by chemical vapor deposition in magnetic tunnel junctions. In ferromagnet/h-BN/ferromagnet heterostructures fabricated on a chip scale, we show tunnel magnetoresistance at room temperature. Measurements at different bias voltages and on multiple devices with different ferromagnetic electrodes establish the spin polarized tunneling using h-BN barriers. These results open the way for integration of 2D monolayer insulating barriers in active spintronic devices and circuits operating at ambient temperature, and for further exploration of their properties and prospects.

The ability to engineer new states of matter and control their spintronic properties by electric fields is at the heart of future information technology. Here, we report a gate-tunable spin-galvanic effect in van der Waals heterostructures of graphene with a semimetal of molybdenum ditelluride at room temperature due to an efficient spin-charge conversion process. Measurements in different device geometries with control over the spin orientations exhibit spin-switch and Hanle spin precession behavior, confirming the spin origin of the signal. The control experiments with the pristine graphene channels do not show any such signals. We explain the experimental spin-galvanic signals by theoretical calculations considering the spin-orbit induced spin-splitting in the bands of the graphene in the heterostructure. The calculations also reveal an unusual spin texture in graphene heterostructure with an anisotropic out-of-plane and in-plane spin polarization. These findings open opportunities to utilize graphene-based heterostructures for gate-controlled spintronic devices. By using 2D materials heterostructures it is possible to exploit the properties of both materials at the interface, for instance, spin-dependent transport for application in spintronic devices. Here, using a heterostructure of MoTe2/Graphene the authors demonstrate a proximity induced spin-galvanic effect which can be controlled by the gate voltage.

Thermal conductivity enhancement in polymers is vital for advanced applications. This study introduces a novel method to align hexagonal boron nitride (hBN) nanosheets within polydimethylsiloxane (PDMS) matrices using a Halbach array to create a highly uniform magnetic field. This technique achieves significant improvements in thermal conductivity by effectively aligning hBN nanosheets. This research shows that hBN nanosheets, when aligned, can drastically enhance thermal conductivity in PDMS composites. Specifically, 10 wt.% vertically aligned hBN nanosheets in a rotating magnetic field achieve a thermal conductivity of 3.58 W mK−1, an impressive 1950% increase over pure PDMS. Additionally, the study explores the effects of orientation on dielectric properties, finding that the orientation of hBN nanosheets also improves electrical insulation and increases the dielectric constant while maintaining extremely low dielectric losses. For a vertically oriented sample, the dielectric constant reaches ≈14, and dielectric losses are as low as 0.0049 at 100 Hz, highlighting their potential for energy storage capacitors. This approach not only enhances thermal management but also maintains or improves electrical insulation, offering promising advances for polymer composites in various technological applications. This study examines the magnetic field alignment of hBN in polymer matrices using a Halbach array. Aligning 10 wt.% hBN within PDMS achieves notable thermal conductivity improvements, reaching up to 3.58 W mK−1. The composites also maintain high electrical insulation, enhanced dielectric properties, and potential functionality as magnetic actuators, enabling applications in energy storage, electronics, and heat management.