Control of spin currents and antiferromagnetic moments via topological surface states for ultralow energy consumption

The efficient electrical detection and manipulation of antiferromagnetic moments is challenging. We show that the spin current and antiferromagnetic moments in the topological insulator/antiferromagnetic insulator bilayer (Bi,Sb) 2 Te 3 /α-Fe 2 O 3 can be controlled via topological surface states. The spin current can control the moment rotation in the antiferromagnetic insulator by means of a giant spin-orbit torque (SOT) generated by the topological surface states, where the switching is detected by the magnetoresistance signal at the interface, named as Rashba-Edelstein magnetoresistance (RE-MR). The required threshold switching current density is 3.5 × 10 ⁶ A cm ⁻² at room temperature, which is one order of magnitude smaller than that required in heavy-metal/antiferromagnetic insulator systems, exhibiting the potential for ultralow energy consumption. Notably, the topological surface states of (Bi,Sb) 2 Te 3 can be modulated by applying a gate voltage, giving rise to electrically controllable RE-MR and SOT switching. Consequently, when the Fermi-level location of (Bi,Sb) 2 Te 3 is tailored by electric fields, the signal of RE-MR is enhanced and the threshold switching current density is further decreased.