Giant Damping-like Spin-Torque Conductivity in a GeTe/Py van der Waals Heterostructure

TL;DR

This paper reports a record-high damping-like spin-torque conductivity in a GeTe/Py heterostructure, driven by multiple spin-orbit effects, enabling efficient room-temperature magnetization control for low-power spintronics.

Contribution

It demonstrates the highest reported damping-like spin-torque conductivity in a ferromagnet/van der Waals heterostructure, combining experimental measurement and first-principles calculations.

Findings

Record-high spin-torque conductivity comparable to heavy metals.

Unconventional spin-orbit torque arising from multiple effects.

Potential for efficient room-temperature spintronic devices.

Abstract

Recent observations of large unconventional spin-orbit torques in van der Waals (vdW) materials are driving intense interest for energy-efficient spintronic applications. A key limitation of ferromagnet (FM)/vdW heterostructures is their lower value of damping-like torque conductivity ($\sigma{\rm_{DL}^{y}}$) compared to the conventional heavy metal-based systems, limiting their prospects for commercial spintronic devices. Here, we report both a giant $\sigma{\rm_{DL}^{y}}$ of $-(1.25 \pm 0.11)\times 10^{5}~\hbar/ 2e~\Omega^{-1}$m$^{-1}$ and an unconventional spin-orbit torque in a heterostructure comprising an FM (Ni$_{80}$Fe$_{20}$) and the vdW material GeTe. The value of $\sigma{\rm_{DL}^{y}}$ represents the highest reported torque conductivity for any FM/vdW interface and is comparable to benchmark heavy metal heterostructures. First-principles calculations reveal that this substantial torque originates from the cooperative interplay of the spin Hall effect, orbital Hall effect, and orbital Rashba effect, assisted by interfacial charge transfer. These findings demonstrate the potential of carefully engineered vdW heterostructures to achieve highly efficient electrical manipulation of magnetization at room temperature, paving the way for next-generation low-power spintronic devices.