Field-Free Spin–Orbit Torque Switching in Janus\nChromium Dichalcogenides

We predict a very\nlarge spin–orbit torque (SOT) capability\nof magnetic chromium-based transition-metal dichalcogenide (TMD) monolayers\nin their Janus forms CrXTe, with X = S, Se. The structural inversion\nsymmetry breaking, inherent to Janus structures is responsible for\na large SOT response generated by giant Rashba splitting, equivalent\nto that obtained by applying a transverse electric field of ∼100\nV nm<sup>–1</sup> in non-Janus CrTe<sub>2</sub>, completely\nout of experimental reach. By performing transport simulations on\ncarefully derived Wannier tight-binding models, Janus systems are\nfound to exhibit an SOT performance comparable to the most efficient\ntwo-dimensional materials, while additionally allowing for field-free\nperpendicular magnetization switching, due to their reduced in-plane\nsymmetry. Altogether, our findings evidence that magnetic Janus TMDs\nstand as suitable candidates for ultimate SOT-MRAM devices in an ultracompact\nself-induced SOT scheme.