  We report the control of vertical magnetization shift (VMS) and exchange bias
through spin-orbit torque (SOT) in Pt/Co/Ir25Mn75/Co heterostructure device.
The exchange bias accompanying with a large relative VMS of about 30 % is
observed after applying a single pulse 40 mA in perpendicular field of 2 kOe.
Furthermore, the field-free SOT-induced variations of VMS and exchange bias is
also observed, which would be related to the effective built-in out-of-plane
field due to unequal upward and downward interfacial spin populations. The
SOT-induced switched fraction of out-of-plane interfacial spins shows a linear
dependence on relative VMS, indicating the number of uncompensated pinned spins
are proportional to the switched interfacial spins. Our finding offers a
comprehensive understanding for electrically manipulating interfacial spins of
AFM materials.
