Exchange Bias Effects in Ferromagnetic MnSb2Te4 down to a Monolayer

The exchange bias (EB) effect is a fundamental phenomenon in conventional systems containing interfaces of ferromagnetic (FM) and antiferromagnetic (AFM) materials and plays a crucial role in magnetic memory technologies. Due to the rapid development of van der Waals (vdW) magnets, the EB effect can be constructed by assembling vdW FM and AFM materials together without the constraints of lattice matching, greatly broadening the understanding of two-dimensional (2D) magnetism. However, the EB effect in singular 2D magnets down to a monolayer has not been realized, where material design plays an important role. Here, we report a distinct EB effect in singular FM MnSb2Te4 flakes, which can be achieved by applying asymmetric field-sweeping ranges. We conjecture that the EB effect is related to the Mn–Sb site-mixing behavior in MnSb2Te4, giving rise to the presence of the pinning sites. The EB field can reach more than 30 mT at 2 K, and its direction and magnitude can be modulated by changing the field-sweeping range, providing a degree of freedom for controlling the EB effect. This work reveals intriguing EB effects in singular vdW magnetic materials and paves the way for low-dimensional spintronic devices.