Anomalous Temperature Dependence of the Magnetocrystalline Anisotropy in Dilute Cobalt-Iron Alloys

Abstract

A study on the temperature dependence of the uniaxial magnetocrystalline anisotropy constant K u1 of Co–Fe alloys containing less than 4.21 at% Fe has been carried out. A strange behavior of K u1 with temperature was found in 0.84∼1.27 at%Fe alloys. On heating, K u1 decreases and changes its sign, followed by an anomalously drastic decrease, and then increases up to the h.c.p.→f.c.c. phase transition temperature. On cooling, K u1 decreases exhibiting a large temperature hysteresis and increases abruptly, becoming positive. This strange phenomenon is cyclic with temperature.