Research Projects

The demand for high-speed and low-power consuming computing architectures with the quest for continuous miniaturization have led to significant attention towards development of new materials and devices with novel functionalities at reduced dimensions. A possible avenue pertains to the utilization of charge, spin, orbital degrees of freedom in magnetic devices, known as spin-orbitronics. Previous studies have focussed on the utilization of intrinsic or interfacial spin-orbit coupling (SOC) heavy metal (HM)/ferromagnet (FM) or antiferromagnet (AFM) heterostructures, where the injection of charge current leverages SOC in the HM layer, converting into spin current, resulting in a torque (spin-orbit torque (SOT)) on the adjacent FM (or AFM). My previous works have demonstrated mesoscopic/nano-metric proof-of-concept SOT-induced magnetic memory devices, solid-state neuromorphic devices with potential advantages of operation speed and unconventional computing. However, the major roadblocks towards its practical implementation requires significant enhancement of SOT efficiency beyond conventional SOC regime, reduction of operating current and power consumption. To address these issues, the aim of the project is to explore a new disruptive avenue where 2D van der Waals (vdW) materials and devices takes the centre stage for emerging quantum spin-orbitronic architectures. The robust intrinsic long range magnetic order down to monolayer limit, low-crystalline symmetry, seamless hetero-assembly and relative twisting of individual layers (Moiré superlattices) in few-layer devices offers new degrees of freedom to effectively modulate fundamental electronic structures, providing an novel approach to generation and manipulation of hitherto unexplored non-equilibrium spin dynamics. Our group has already established vdW single crystal synthesis and fabrication of few-layer vdW-devices (detailed in technical document). Recent studies have predicted that the low crystalline symmetry in vdW devices can lead to remarkable manifestations resulting in new intrinsic SOTs, unique anisotropy-like SOTs and torques arising from quantum correlations between spin and pseudospin angular momentum in 2D heterostructures, resilient to disorder and virtually non-existent in quasi-3D or 3D regime. The sequential stacking and control of the relative rotation between different layers also allows band engineering though Moiré superlattices while proximity effects could reveal unprecedented manifestations of entanglement and many-body physics, possibly leading to emergent SOTs beyond the conventional SOC effects in solid-state systems. Investigations of the spin-dynamics and SOTs in all-vdW heterostructures will be carried out by our home-built ferromagnetic resonance and low-frequency Harmonic measurement techniques. The proposed investigations on 2D vdW heterostructures are expected to initiate an unexplored avenue for the development of functional quantum spin-orbitronic devices.