Atomic-scale characterization of few-layer Cr₅Se₈

The realization of magnetic order at the two-dimensional limit is currently a priority for Materials Science. In this arena, self-intercalated 2D transition metal chalcogenides have emerged as candidate magnetic materials with unprecedented robust chemical stability, which could enable their integration in durable, flexible magnetic devices [1]. Here we perform combined atomic-scale structural and electronic characterization of few layer Cr₅Se₈ with its mesoscopic magnetic characterization. We have studied the atomic, electronic and magnetic structure of MBE-grown few-layer Cr₅Se₈ on graphene substrates (BLG/SiC(0001) and HOPG) by means of 4.2K-STM/STS and XMCD measurements. STM imaging reveals that Cr₅Se₈ present both Se- and Cr-terminations, the latter showing a 2x2 periodicity in the Cr plane stable up to room temperature. Both terminations exhibit a semiconducting behavior with an accused layer-dependent gap value maximized at 1.2 eV for ML. Lastly, our XMCD measurements are compatible with a weak ferromagnetic ground state down to 2K.