Magnetic anisotropy and its microstructural origin in epitaxially grown SmCo thin films

Microstructural features and magnetic behavior of epitaxially grown SmCo thin films with very high in-plane anisotropy are presented. Transmission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using de and SQUID magnetometers. 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 bicrystalline microstructure, whereas in the latter, a uniaxial one is observed, Both 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 strong 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 related to intergranular exchange interactions and local variation in magnetocrystalline anisotropy constants are discussed.