Highly efficient field-free switching by orbital Hall torque in a MoS2-based device operating at room temperature

Abstract: Charge-to-spin and spin-to-charge conversion mechanisms in high spin-orbit materials are the new frontier of memory devices. They operate via spin-orbit torque (SOT) switching of a magnetic electrode, driven by an applied charge current. In this work, we propose a novel memory device based on the semiconducting two-dimensional centrosymmetric transition metal dichalcogenide (TMD) MoS2, that operates as a SOT device in the writing process and a spin valve in the reading process. We demonstrate that stable voltage states at room temperature can be deterministically controlled by a switching current density as low as 3.2x10^4 A/cm^2 even in zero field, owed to a tilted geometry and a differential voltage architecture. An applied field of 50-100 Oe can be used as a characterizing control parameter for the state switching. Ab initio calculations of spin Hall effect (SHE) and orbital Hall effect (OHE) point to the latter as the most likely responsible for the generation of the SOT in the magnetic electrode. The large value of OHC in bulk MoS2 makes our device competitive in terms of energetic efficiency and could be integrated in TMD heterostructures to design memory devices with multiple magnetization states for non-Boolean computation.