Anomalous Behavior of Magnetic Anisotropy of Amorphous Co40Fe43B17 Thin Film Sandwiched Between Mo Layers

Anomalous behavior of magnetic anisotropy in Co
₄₀
Fe
₄₃
B
₁₇
film sandwiched between Mo layers has been observed as a function of thermal annealing at different temperatures. The as-deposited amorphous film exhibits a uniaxial magnetic anisotropy, the origin of which can be traced to quenched-in stresses. With thermal annealing up to 300 °C, anisotropy remains unchanged. We observe an anomalous magnetic reversal near the hard axis (HA) in the samples annealed at 350 °C and above. The anomaly of the occurrence of nonuniform magnetization near HA can be explained in terms of distribution of easy magnetization direction, as evidenced by the ripple domain structure in Kerr microscopy images.