Tuning the direction of exchange bias in ferromagnetic/antiferromagnetic bilayer by angular-dependent spin-polarized current

The angular dependence of an external magnetic field applied with an in-plane alternating pulse that induces a new direction of exchange bias (EB) is observed in an NiFe/IrMn bilayer. Depending strongly on the direction of the external field, EB field gradually orients along the external field with the increase in current pulse, and the new direction of EB is finally established. Furthermore, the new direction of EB can also be induced along the external field at once when the applied pulse is larger than the critical current. Because the strength and direction of the EB is highly correlated with the micromagnetic state distribution of the antiferromagnet, the observations are explained by the spin torque exerted on the antiferromagnetic moments and provide evidence for the prediction of spin transfer and current-induced switching in antiferromagnets.