A study on CoCrPtB/CoTb magnetically coupled media

Abstract

Magnetically coupled media were proposed to overcome the thermal stability problem in future ultra-high density magnetic recording media. Two-layer structure, i.e. a CoCrPtB magnetic layer with a CoTb stabilizing layer, was used in magnetically coupled media. The perpendicular magnetic property and magnetic thermal stability of films with the above structure were studied. It was found the perpendicular growth of CoCrPtB layer was achieved and the CoTb layer was amorphous. By changing the thickness and Tb content of the CoTb stabilizing layer, the magnetic and thermal properties of the media were enhanced greatly. It was found the thermal stability factor (SF) enhanced to a value 2-2.5 times of a CoCrPtB film without the stabilizing layer. The stabilizing layer also affected the magnetic reversal process, thus the coercivity of CoCrPtB film was enhanced. Hysteresis loops with three-step magnetization switching were observed, which indicates a strong exchange coupling effect between the two layers. In this loop a strong exchange coupling constant is estimated about 1.2 erg/cm2.