Current-induced magnetization switching in all-oxide heterostructures*

The electrical switching of magnetization through spin-orbit torque (SOT) holds promise for application in information technologies. Materials with strong spin-orbit coupling, such as heavy metals can convert a charge current into a spin current. The spin current can then execute a transfer torque on the magnetization of a neighboring magnetic layer, usually a ferromagnetic metal like CoFeB, and reverse its magnetization. Here, we combine a ferromagnetic transition metal oxide with an oxide with strong spin-orbit coupling to demonstrate all-oxide SOT devices. We show current-induced magnetization switching in SrIrO3/SrRuO3 bilayer structures. By controlling the magnetocrystalline anisotropy of SrRuO3 on (001)- and (110)-oriented SrTiO3 (STO) substrates, we designed two types of SOT switching schemes. For the bilayer on the STO(001) substrate, a magnetic-field-free switching was achieved, which remained undisturbed even when the external magnetic field reached 100 mT. The charge-to-spin conversion efficiency for the bilayer on the STO(110) substrate ranged from 0.58 to 0.86, depending on the directionality of the current flow with respect to the crystalline symmetry.