  With ultra-fast writing capacity and high reliability, the spin-orbit torque
is regarded as a promising alternative to fabricate next-generation magnetic
random access memory. However, the three-terminal setup can be challenging when
scaling down the cell size. In particular, the thermal stability is an
important issue. Here we demonstrate that the current-pulse-induced
perpendicular exchange bias can significantly relieve the concern of thermal
stability. The switching of the exchange bias direction is induced by the
spin-orbit torque when passing current pulses through the Pt/Co system with an
inserted IrMn antiferromagnetic layer. Manipulating the current-pulse-induced
exchange bias, spin-orbit-torque switching at zero field between states with
unidirectional anisotropy is achieved and the thermal agitation of the magnetic
moment is strongly suppressed. The spin-orbit torque mechanism provides an
innovative method to generate and to control the exchange bias by electrical
means, which enables us to realize the new switching mechanism of highly stable
perpendicular memory cells.
