MAGNETIC-ANISOTROPY AND ITS MICROSTRUCTURAL ORIGIN IN EPITAXIALLY GROWN SMCO THIN-FILMS

Microstructural features and magnetic behavior of epitaxially grown Sm Co thin films with very high in-plane anisotropy are presented. Transm ission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using de and SQUID magneto meters. Two substrate orientations were studied, i.e., MgO(100)/Cr(100 )/SmCo(11 (2) over bar 0) and MgO(110)/Cr(211)/SmCo(1 (1) over bar 00) . In the former, the SmCo(11 (2) over bar 0) film shows a bicrystallin e microstructure, whereas in the latter, a uniaxial one is observed, B oth microstructures consist of grains with a mixture of SmCo3, Sm2Co7 and SmCo5 polytypoids. A deviation from the c-axes was observed in the in-plane anisotropy of the SmCo(11 (2) over bar 0) thin film. A stron g exchange interaction between the grains would, in principle, explain the observed deviation. On the other hand, both SmCo(11 (2) over bar 0) and (1 (1) over bar 00) thin films show very high coercivity values with pinning-type characteristics. Possible coercivity mechanisms rel ated to intergranular exchange interactions and local variation in mag netocrystalline anisotropy constants are discussed.