Field-free control of exchange bias by spin Hall currents

Abstract

A trilayer structure consisting of ferromagnetic alloy CoFeB/antiferromagnetic IrMn/heavy metal Pt layers was prepared, and the manipulation of its exchange bias effect was achieved without applying an external magnetic field. Spin polarized current, generated by the spin Hall effect of the electrical current through the Pt layer, was shown to be able to control the spin alignment state in the neighboring antiferromagnetic material as well as the corresponding exchange bias effect in the ferromagnet coupled to the antiferromagnet. The results demonstrated stable and reliable switching of the spin structure in antiferromagnets, providing a useful route to all-electrical manipulation of antiferromagnetic states without a need for the bulky global application of the external magnetic field. Therefore, with the results presented in the present work, precise control of magnetism including both ferromagnets and antiferromagnets on submicron to nanometer length scales can be expected.