Domain Structure and Magnetic Properties of Epitaxial Rare Earth-Transition Metal Thin Films

Rare Earth-Transition Metal permanent magnet films were epitaxially grown by pulsed laser deposition on heated MgO single crystal substrates of different orientations. The epitaxial growth relation of film, buffer and substrate is studied by pole figure measurements and its consequences on the anisotropic magnetic behavior are discussed. In the investigated material systems, RCo5 (R = Sm, Pr) and Nd-Fe-B, high anisotropies and coercivities are achieved, the film morphology, domain structure and the coercivity mechanism are, however, distinctly different. The small scaled domain structure found for SmCo5 and PrCo5 films is a consequence of the small grain sizes and the magnetization process is dominated by strong pinning. Nd2Fe14B based films, on the other hand, are nucleation type magnets and coercivity is influenced by film morphology and roughness.