Exchange effect in TM-TbCo/RE-TbCo double layer films

The High saturation magnetization (M-s) media are desired to yield large flux density for high resolution giant magnetoresistive head readout in Heat Assisted Magnetic Recording (HAMR). To ensure adequate stability of small size domains, the media for HAMR should possess large coercivity (Hc). In this work, we study of interface wall energy and the behavior of the magnetization of each layer in exchange coupled doubled-layered (ECDL) films. The Tb17Co83 (90 nm)/Tb30Co70 ECDL films with different Tb30Co70 thickness (20, 35, 50, 70, 90 nm) are made to increase the M, value. As the thickness of Tb30Co70 film increase from 20 to 90 nm, the coercivity of the films increases from 2.5 to 8 kOe. The enhanced coercivity of ECDL films is due to the formation of domain wall at the interface of the ECDL film. As the Tb30Co70 increases from 20 to 90 rim, the Ms value of the films decreases from 380 to 330 emu/cm(3). Due to Co has larger magnetic moment than that of Tb at room temperature, the resulting Ms value of the films decreases with increasing the thickness of Tb30Co70 layer.