Understanding the correlation between electronic structure and asymmetric defect distribution in dual-metal Janus FeReS3 monolayer

Spin-related electronic structure plays an important role in designing new-type spintronic devices. Herein, we unravel the ferromagnetic and optical behaviors of double-faced FeReS3 with asymmetric defects based on the density functional theory. Different from conventional two-dimensional materials, the spontaneous spin polarization strongly relates with the spatial distribution of anion defects. The superficial and intrastratal S defects make the occupation of Fe-3d orbital unfilled, leading to a distinguishable spin polarization. Our results indicate that structural deformation can regulate the strong exchange interactions between spin sites for achieving room temperature ferromagnetism; interestingly, the S defects at opposite surface cannot give rise to this behavior. We propose to identify the types of S defects in double-faced FeReS3 by comparing their absorption fingerprints.