Prediction of Two-Dimensional High-TC f-electron Ferromagnetic Semiconductor

Two-dimensional (2D) ferromagnetic semiconductors (FMSs) exhibit novel spin-dependent electronic and optical properties, opening up exciting opportunities for nanoscale spintronic devices. However, experimentally confirmed 2D FMSs based on transition metal ions are rather limited and their performances are not satisfied, e.g. typically with low Curie temperatures and small magnetic signals. Different from most known 2D magnets based on d-electron, here an exotic 2D FMS based on rare-earth ion with f-electrons, GdI2 monolayer, is predicted to own a large magnetization (8 μB/f.u.), whose ferromagnetism can survive near room temperature (241 K). In addition, with a small exfoliation energy from its layered van der Waals (vdW) bulk, this GdI2 monolayer holds excellent dynamical and thermal stabilities, making our prediction quite promising in experiments. Our prediction not only offers a compelling FMS for spintronics, but also provides an alternative route to acquire more high-performance 2D FMSs, going beyond pure d-electron compounds.