Ho-Coスパッター薄膜の磁気特性と構造

抄録

An experimental study of perpendicular magnetic anisotropy and microstructure of Ho-Co sputtered films fabricated at various bias voltages has been carried out. The perpendicular magnetic anisotropy constant K_u is not much changed by negative bias voltage (−V_b). However, a detailed examination of the cross-sectional structure made by high voltage electron microscopy and using a “micro-micro diffraction” technique reveals a strong dependence of film structure on (−V_b). The films made at V_b=0 consist of fine columns of 100 to 200Å diameter surrounded by a network of less dense materials of about 30Å thickness. With increasing (−V_b), a region near one side of film surface, giving rise to a spotty diffraction pattern, appears. With further increasing (−V_b), a highly porous region is found on one side of the film cross-section, but a columnar structure still exists on the other side.
The present result implies that a columnar structure is responsible for the perpendicular magnetic anisotropy for films made at no bias voltage, but other mechanisms must be taken into account for higher bias voltages.