High exchange bias field induced in ferrimagnetic bilayers of amorphous rare earth–transition-metal alloys

Abstract

The magnetic reversal processes of exchange-coupled double layers (ECDL) and corresponding single layers of rare-earth–transition metal were studied by magneto-optical Faraday rotation (FR). The dependence of FR on the temperature shows a transition of DyFeCo/TbFeCo ECDL from one type to another near the compensation temperature of single layers. Minor and major hysteresis loops allowed us to measure the exchange bias field induced by DyFeCo, which has also been calculated with an analytical model. We have also observed that an unusual hystersis loop appears few celsius degrees before this transition occurs. In this letter, we analyze and describe different magnetization states, and various kinds of magnetization processes, including the usual and unusual FR loops, are explained in detail.