Field-driven domain wall creep motion in ferrimagnetic Tb/CoFeB/MgO microwires

Abstract

We studied field-driven domain wall (DW) creep motion in ferrimagnetic Tb/CoFeB/MgO with respect to CoFeB thickness by using a real-time DW detection method. The DW velocity for Tb(5 nm)/CoFeB(1.0 ∼ 1.8 nm)/MgO microwires was measured at room temperature. The DW velocity increases with increasing the CoFeB thickness, which is contrary to a general trend in the ferromagnetic wire. From the creep-scaling analysis, the characteristic velocity at which the DW moves when the energy barrier vanishes is found to be a dominant contribution to the DW velocity. Our results clarify the ferrimagnetic DW dynamics in the creep regime.