UC Berkeley

Utilizing the magneto-optic Kerr effect and Kerr microscopy measurements, we investigated the antiferromagnetic (AFM) domain switching process at different magnetic fields in a single-crystalline Fe/CoO bilayer grown on MgO(001) substrate. In spite of the zero-net magnetic moment in the CoO layer, we find that the activation energy barrier of CoO AFM domain switching decreased at larger magnetic field. To separate the different behaviors of domain nucleation and domain wall motion during the CoO spin switching process, a new analytical method was developed. Using this method, we found that the CoO domain nucleation energy barrier exhibited a jump at a critical magnetic field while the CoO domain wall motion experienced only a tiny energy barrier variation. The field-dependent behaviors of the energy barriers were attributed to the formation of a spiral domain wall in the Fe layer during its magnetization reversal and this was supported by micromagnetic simulations.