Electrical manipulation and detection of antiferromagnetism in magnetic tunnel junctions

Electrical manipulation and detection of antiferromagnetic order could be used to create reliable and fast spintronic memory devices. The state of antiferromagnets can be read out using signals such as the anisotropic magnetoresistance and anomalous Hall effect, but these signals remain low, which restricts device development. Here we report the electrical detection of antiferromagnetism in Pt/IrMn/CoFeB/MgO/CoFeB three-terminal magnetic tunnel junctions using tunnelling magnetoresistance. We measure a tunnelling magnetoresistance ratio of over 80%, which is achieved by imprinting the antiferromagnetic state of IrMn on the ferromagnetic CoFeB free layer. We show current-polarity-dependent switching of IrMn down to 0.8 ns and identify two switching mechanisms: a heat-driven mode and a spin–orbit-torque-driven mode. The dominant switching mechanism depends on the current pulse width. Numerical simulations suggest that the spin–orbit torque generated by Pt induces the precession of IrMn moments and that exchange coupling at the IrMn/CoFeB interface determines the switching polarity of IrMn.