MICROSTRUCTURES AND MAGNETIC-PROPERTIES OF CO/CU LAYERED FILMS PREPARED BY EVAPORATION

Co/Cu multiple layered films with equal layer thicknesses were prepared by evaporation on copper buffer layers with a [111] texture. Transmission electron microscopy and X-ray diffraction measurements showed that the copper layers grew with a [111] texture, and that h.c.p. cobalt layers grew with a [0001] texture and f.c.c. cobalt layers with a [111] texture for thicknesses above and below about 5 nm respectively. The specimens were composed of columnar grains which grew perpendicularly to the copper buffer layer. Magnetic measurements using a room temperature vibrating sample magnetometer revealed that the easy axis of magnetization shifted from in-plane to normal to the specimens as the periodicities exceeded several tens of nanometres. Values of the saturation magnetization were close to those of bulk cobalt (about 1.4×106 A m-1) for cobalt thicknesses above 2.5 nm and somewhat lower below. Coercive forces decreased slowly with decreasing cobalt thickness and abruptly below a thickness of about 5 nm. © 1990.