PURPOSE: To obtain a Co-Cu artificial grating film large in a MR (magnetic resistance) ratio by a method wherein a sputtering process is carried out in an inert gas atmosphere of prescribed pressure to alternately laminate a layer mainly formed of Co and another layer mainly formed of Cu an a non-magnetic support for the formation of a Co-Cu artificial grating film.

CONSTITUTION: A sputtering process is carried out in an inert gas of 0.07 to 0.5Pa to alternately laminate a layer mainly formed of Co and another layer mainly formed of Cu on a non-magnetic support for the formation of a Co-Cu artificial grating film. At this point, the layer mainly formed of Co and the other layer mainly formed of Cu are formed as thick as 0.5 to 3nm and 1.7 to 4nm respectively. By this setup, a Co-Cu artificial grating film possessed of a large MR ratio even in a magnetic field lower than 0.1T at a room temperature or below can be obtained.