Magnetization reversal of Co/Cu/Co elliptical elements studied by in-field magnetic force microscope and micromagnetic simulation

Abstract

The magnetization reversal process of 10 nm Au/5 nm Co/6 nm Cu/30 nm Co elements with a 100 nm×200 nm elliptical shape was studied using a magnetic force microscope (MFM) with a variable in-plane applied field and a high coercivity tip. MFM observations showed that the ground states of top and bottom Co layers are all single domain, and their magnetizations reverse sharply layer by layer. According to the contrast change of MFM images of a single elliptical element by a sweeping applied field, a two-step hysteresis loop characterized by sharp reversal of magnetization was obtained. Micromagnetic simulations exhibited that the sharp reversal of magnetization agrees with MFM observations, and the magnetization reversal mechanisms are “quasicoherent” and vortex for the top and bottom Co layers, respectively.