Field dependence of antiferromagnetic domain switching in epitaxial Fe/CoO/MgO(001) systems

Abstract

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 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.

Antiferromagnetic domain switching modulated by an ultrathin Co interlayer in the Fe/Co/CoO/MgO(001) system

“…The magnetic hysteresis loop exhibits an EA square loop when H H FC , and the doublesplit hard-axis (HA) when H ⊥ H FC , as shown in Fig. 2(c) [28,29]. The magnitude of this exchange-coupling induced uniaxial anisotropy can be retrieved from the splitting field H S of the HA double-split loop, shown in Fig.…”

“…Recently, we reported that the activation energy barrier of CoO AFM domain switching in the Fe/CoO(001) system strongly decreases with the applied magnetic field, and this behavior was attributed to the FM noncollinear spin profile during its magnetization reversal [29]. It is possible that the FM spin structure near the CoO interface is modulated by the Co layer due to the difference of the anisotropy and exchange coupling constant between Fe and Co layers.…”

“…The 90°-switching process of CoO AFM domain driven by the exchange coupling was revealed by measuring the Fe remanent Kerr signal, and the AFM domain switching energy barrier can be characterized through a temperature-dependent measurement [28]. The AFM domain switching energy barrier in the Fe/CoO(001) system decreases with the applied field due to the spiral-like spin configuration in the Fe layer, which can be tailored by the field strength [29]. Generally speaking, the AFM domain evolution in a FM/AFM system is driven by the exchange coupling between FM and AFM layers, thus the magnetic property at the AFM/FM interface plays important role on AFM domain switching in the Fe/CoO(001) system.…”