For example, for the convenience of manufacture, the thickness of the insulating film 22 should preferably be 10 ??m or less. [0076] As for the materials for these first and second ferromagnetic layers 23 and 24, there is not any particular limitation, and therefore, it is possible to employ a metal such as Fe, Co, Ni or an alloy thereof; oxides such as CrO2, RXMnO3-y (R: rare earth element; X: Ca