Joule Heating Effect on Field-Free Spin-Orbit Torque Magnetization Switching in Exchange Biased Systems*

Deterministic spin-orbit torque (SOT) switching of perpendicular magnetization is usually achieved with an external magnetic field, not desired for practical applications. However, it has been shown that field-free switching can be realized using the in-plane exchange bias (EB) at an antiferromagnet/ferromagnet (AFM/FM) interface. We study Pt/CoFe/IrMn system and achieve field-free switching. Then, we quantitatively investigate the Joule heating effect in AFM/FM structures, and show that applying high current densities for switching may raise the device’s temperature close to the blocking temperature. Consequently, if not properly designed, the in-plane EB may be lost after several switching cycles, and degrade the field-free switching. Next, to enable readout using magnetic tunnel junctions, we study IrMn/CoFeB/MgO structure, where IrMn (an AFM) provides both the EB and SOT. We show that field-free switching can be realized in this structure and we discuss the performance and heating effects, providing important insights for practical field-free SOT switching in AFM/FM systems.