Research Projects

Spin-orbit torque (SOT) has emerged as a leading mechanism for efficient current-induced magnetization switching in spintronic devices. It offers a scalable alternative to magnetic field-based switching by utilizing the spin Hall effect (SHE) or Rashba-Edelstein effects (REE) at heavy metal (HM)/ferromagnet (FM) interfaces. Conventionally, SOT switching has been studied using ST-FMR and harmonic Hall measurements. However, recent research has shifted focus toward higher-order harmonic signals, especially third harmonic detection, as they provide enhanced sensitivity to nonlinear spin transport processes, which include thermally induced magnetization reduction, magnetoelastic effect, and thermally induced SOT effect. Our proposal aims to design and engineer heterostructures combining FMs and AFM with high SOC materials like HMs and 2-dimensional electron gases (2DEGs) at the oxide interface to address the various gaps in studying the SOT phenomena. The schematic illustration in the figure (uploaded in the methodology section) provides a comprehensive outline of the planned investigations on the mechanisms underlying SOT phenomena across different material systems. The following major unexplored areas will be investigated systematically. • Systematic Study of SOT and Accurate Quantification of Torque Components: Systematically study SOTs under a controlled condition by employing spin Hall magnetoresistance (SMR) and harmonic (second and third) Hall measurements by isolating the nonlinear thermal effects. • Strain Control of SOT: The effect of piezo strain can modulate magnetic anisotropy thereby influencing both the damping-like and field-like components of the SOT. The torque tunability and deterministic switching need to be explored through strain engineering. • Study of SOT Phenomena at Oxide Interface: The 2DEG at the oxide interface shows high spin transparency, giant spin-charge interconversion, and enhanced spin mixing conductance. The detailed investigation on 2DEG-based SOT will be carried out to explore Rashba-type spin–orbit coupling beyond conventional spin Hall effect (SHE) contributions. It will also be important to distinguish the SOT-induced voltages and the additional contribution of thermal effects like the anomalous Nernst effect (ANE) and spin Seebeck effect (SSE), which are expected to be prominent in oxide-based systems. • Efficient Magnetization Switching in Oxide-based PMA Systems: In HM/FM SOT heterostructures, the thickness of the ferromagnetic layer is typically limited to a few nanometers due to the short spin coherence length resulting from rapid spin dephasing. In this context, oxide-based PMA magnets have gained considerable attention for their ability to sustain PMA up to higher thickness. Efficient magnetization switching is proposed in oxide magnets due to the lower damping and reduced saturation magnetization, which are critical for reducing the switching current density.