Giant orbital torque-driven picosecond switching in magnetic tunnel junctions

Orbital effects and orbital torque (OT) were recently discovered as a novel pathway for driving the magnetic moment. However, the development of OT-based magnetic memories suffers from low orbital-to-spin conversion efficiency and incompatibility with magnetic tunnel junctions (MTJs). Here we demonstrate OT-MTJ devices based on Ru/W bilayer, achieving an effective spin-orbit Hall conductivity of -12,600 ħ/2e Ω^-1 cm^-1. The giant orbital torque originates from the strong orbital effects in the Ru layer and an orbital-to-spin conversion efficiency exceeding 90% in the α-W layer because of the large orbit-spin diffusivity. By harnessing the giant orbital torque, we experimentally achieve switching of OT-MTJs by short pulses down to 28.7 ps, with picosecond-switching dynamics captured. Compared with β-W-based spin-orbit torque-MTJs, the OT-MTJs offer a five to eight-fold reduction in driving voltages, and a highly uniform resistance distribution of <1 Ω across write channels. Our work bridges the critical gap between orbital effects and magnetic memory applications.