NANOSTRUCTURE AND MAGNETIC-ANISOTROPY OF CO AU MULTILAYERS/

Multilayer Co/Au films were deposited on 40 nm Au underlayer by magnet ron sputtering. The Co thickness is kept constant at 0.5 nm while the Au thickness is varied from 0.5 to 8 nm. Magnetic measurements show th at the perpendicular anisotropy of the films changes from 3 x 10(6) to 1.5 x 10(6) erg/cm(3) as the Au thickness changes from 6 to 1 nm. Two films of (Co 0.5 nm/Au 6 nm)x9/Au 40 nm (denoted Au6) and (Co 0.5 nm/ Au 1 nm)x50/Au 40 nm (denoted Au1) were examined by transmission elect ron microscopy. For the Au6 film, a bright-field image reveals the cur vature of the multilayer. High-resolution electron microscopy shows th at the curvature consists of many atomic steps leading to a rough inte rface. The Au layer has the fee structure (ABCABC stacking) and the Co layer of two atomic layers interrupts the ABCABC stacking of Au and c ould be fitted to the AB stacking. In contrast to the Au6 film, the Au layers and the Co layers in the Au1 film cannot be identified in the high-resolution electron microscopy image. Bright field transmission e lectron microscopy images reveal the evidence of local clustering of A u and Co. A high density of 1/3[111]a dislocations is observed which s upports the clustering argument. The anisotropy of the films is discus sed in connection with the observed nanostructure involving the steps and the clustering of Au and Co. (C) 1997 American Institute of Physic s.