Magnetization Switching in Exchange-Coupled Systems

摘要

A new route for reducing the switching fieldn$(H_{mathrm{s}mathrm{w}})$nwhile maintaining the thermal stability of magnetization is indispensable for further increase in areal density of magnetic storage media. From the viewpoint of thermal stability of magnetization in nanoscale,n$L1_{0}-$n$ FePt is one of the candidate materials for the recording media because of its high uniaxial magnetic anisotropyn$(K_{mathrm{u}})$n. Thus, it is required thatn$H_{mathrm{s}mathrm{w}}$nofn$L1_{0}-$nFePt is effectively reduced only when data are written into magnetic bits. We previously reported that spin wave excitation remarkably reducedn$H_{mathrm{s}mathrm{w}}$nfor the exchange-coupledn$L1_{0}-$nFePt / Nin81nFen19n(Permalloy; Py) bilayer with in-plane magnetization [1]– [3]. From the practical point of view, however, suchn$H_{mathrm{s}mathrm{w}}$nreduction should be done for a bilayer with an out-of-plane configuration of magnetic moments.