Efficient magnetic switching is a cornerstone for advancing spintronics, particularly for energy-efficient data storage and memory devices. Here, we report the electrical switching of spin-flips in V-doped WSe2 multilayers, a van der Waals (vdW)-layered diluted magnetic semiconductor (DMS), demonstrating ultralow-power switching operation at room temperature. Our study reveals unique linear magnetoresistance and parabolic magnetoresistance states, where electrical modulation induces transitions between interlayered ferromagnetic, ferrimagnetic, and antiferromagnetic configurations. We identify an unconventional linear magnetoresistance hysteresis characterized by electrically driven spin flip/flop switching, distinct from conventional random network disorder or linear band-dispersion mechanisms. Applying an electrical voltage across vertical vdW layered V-doped WSe2 multilayers generates the spin currents at room temperature, driving spin-flip transitions from ferromagnetic to antiferromagnetic states due to a strong spin transfer torque effect. Notably, the critical current density reaches an ultralow value of 10-1Acm-2, accompanied by pico-watt power consumption, a record-low spin current density by a six-order-of-magnitude improvement over conventional spintronic devices. These findings establish the V-doped WSe2 multilayer device as a transformative platform for ultralow power spintronics, underscoring the potential of vdW-layered DMS systems for next generation energy-efficient spintronic technologies. <<more>>

Linear resistivity–temperature (R–T) at low temperatures, referred to as strange metal (SM), is an unusual characteristic observed in strongly correlated systems. SM is often mingled with superconductivity and magnetism in various materials. Here, we report a linear R–T relation in a hole-doped, degenerate spin-valley (SV) semiconductor, V0.25W0.75Se2, with hole pockets in the valence band. SM emerges over a wide temperature range (1.8–150 K) without any apparent superconductivity down to 110 mK. This finding opens possible routes for understanding strange metal behavior through the interplay of strong SOC and strong Coulomb interactions. <<more>>

Fluctuations are ubiquitous in magnetic materials and can cause random telegraph noise. Such noise is of potential use in systems such as spiking neuron devices, random number generators and probability bits. Here we report electrically tunable magnetic fluctuations and random telegraph noise in multilayered vanadium-doped tungsten diselenide (WSe2) using vertical tunnelling heterostructure devices composed of graphene/vanadium-doped WSe2/graphene and magnetoresistance measurements. We identify bistable magnetic states through discrete Gaussian peaks in the random telegraph noise histogram and the 1/f2 features of the noise power spectrum. Three categories of fluctuation are detected: small resistance fluctuations at high temperatures due to intralayer coupling between the magnetic domains; large resistance changes over a wide range of temperatures; and persistent large resistance changes at low temperatures due to magnetic interlayer coupling. We also show that the bistable state and cut-off frequency of the random telegraph noise can be modulated with an electric bias. <<more>>

Doping van der Waals layered semiconductors with magnetic atoms is a simple and effective approach to induce magnetism. However, investigation of the electrical properties of such two-dimensional (2D) semiconductors and the modulation of their magnetic order for spintronics is still lacking. Herein, we report a giant Zeeman shift from the spin-polarized state in tungsten diselenide (WSe2) doped with a small amount of vanadium (V) atoms (~0.1%). The Zeeman shift was measured via resonant magnetotunneling spectroscopy with a vertical graphite/V-WSe2/graphite heterojunction. The p-type doping state near the valence band is substantially shifted under an external magnetic field by 7.8 meV/T, equivalent to a giant g factor of approximately 135, an order of magnitude higher than that of other two-dimensional magnetic semiconductors. The ferromagnetic order of the spin glass state and its long-range interaction are revealed by the remanence of magnetoresistance between the zero-field cooling and field-cooling processes as well as magnetoresistance hysteresis. The ferromagnetic glass order is fully established at 50K, whereas the long-range interaction persists at higher temperatures of up to 300K in V-doped WSe2 flakes with an approximate thickness of 5 nm. Our work sheds light on the magnetic nature of V-doped WSe2 semiconductors and paves the way for future spintronics based on two-dimensional van der Waals magnetic semiconductors. <<more>>

Diluted magnetic semiconductors including Mn‐doped GaAs are attractive for gate‐controlled spintronics but Curie transition at room temperature with long‐range ferromagnetic order is still debatable to date. Here, the room‐temperature ferromagnetic domains with long‐range order in semiconducting V‐doped WSe2 monolayer synthesized by chemical vapor deposition are reported. Ferromagnetic order is manifested using magnetic force microscopy up to 360 K, while retaining high on/off current ratio of ≈105 at 0.1% V‐doping concentration. The V‐substitution to W sites keeps a V–V separation distance of 5 nm without V–V aggregation, scrutinized by high‐resolution scanning transmission electron microscopy. More importantly, the ferromagnetic order is clearly modulated by applying a back‐gate bias. The findings open new opportunities for using 2D transition metal dichalcogenides for future spintronics.  <<more>>

Multilayer graphene and its stacking order provide both fundamentally intriguing properties and technological engineering applications. Several approaches to control the stacking order have been demonstrated, but a method of precisely controlling the number of layers with desired stacking sequences is still lacking. Here, we propose an approach for controlling the layer thickness and crystallographic stacking sequence of multilayer graphene films at the wafer scale via Cu–Si alloy formation using direct chemical vapour deposition. C atoms are introduced by tuning the ultra-low-limit CH4 concentration to form a SiC layer, reaching one to four graphene layers at the wafer scale after Si sublimation. The crystallographic structure of single-crystalline or uniformly oriented bilayer (AB), trilayer (ABA) and tetralayer (ABCA) graphene are determined via nano-angle-resolved photoemission spectroscopy, which agrees with theoretical calculations, Raman spectroscopy and transport measurements. The present study takes a step towards the layer-controlled growth of graphite and other two-dimensional materials.

 <<more>>