Energy-efficient field-free unconventional spin-orbit torque magnetization switching dynamics in van der Waals heterostructures

The van der Waals (vdW) heterostructure of emerging two-dimensional (2D) quantum materials, with control over their quantum geometries, crystal symmetries, spin-orbit coupling, and magnetic anisotropies, provides a new platform for generating unconventional nonlinear Hall effects, spin polarization and efficiently controlling the magnetization dynamics for non-volatile spin-based computing. However, so far, the generation of a large out-of-plane spin polarization is limited to achieve energy-efficient field-free magnetization switching and spin dynamics measurements in all-2D vdW heterostructure are so far missing, where the interplay between spins and magnetization dynamics should enable the design of ultrafast spintronic devices. Here, we demonstrate magnetization dynamics and energy-efficient field-free spin-orbit torque (SOT) switching of out-of-plane magnet Fe3GaTe2 due to unconventional Berry curvature-induced out-of-plane spin polarization from a topological Weyl semimetal TaIrTe4 in a vdW heterostructure at room temperature. We observed a large non-linear 2nd harmonic Hall signal at room temperature and evaluated the SOT-induced magnetization dynamics with a large damping-like torque of 4.83±0.59 mT per MAcm ^(-2) . Deterministic field-free SOT magnetization switching in vdW heterostructure of TaIrTe4/Fe3GaTe2 is observed at room temperature with a low current and power density of 1.81 ×10 ¹⁰ A/m ² and 0.175×10 ¹⁵ W/m ³ , respectively, which is an order of magnitude better than that of conventional systems. From the magnetization switching experiments, the SOT efficiency is found to be 3.95 with a very large spin Hall conductivity of 7.39×10 ⁶ ħ/2e (Ω m) ^(–1) . These findings on all-vdW heterostructures offer a promising route to energy-efficient and external field-free ultrafast spintronic technologies.