Textured growth and microstructure of pulsed laser deposited Nb/Cr/SmCo5 hybrid structures

Hybrid structures based on superconducting Nb and highly coercive ferromagnetic SmCo5 films grown on MgO(100) substrates were fabricated by pulsed laser deposition under UHV conditions. Thin film architectures of SmCo5 on Nb and the reversed system both with and without Cr spacer layer between superconductor and ferromagnet were examined by transmission electron microscopy and X-ray diffraction concerning their microstructure and epitaxial relationship, respectively. For SmCo5 on Nb with thick intermediate Cr spacer the epitaxial relationship MgO(001)[100]//Cr(001)[110]//Nb(001)[110]//Cr(001)[110]//SmCo5(11-20)[0001]//Cr(001)[110] was found. With decreasing thickness of the Cr spacer layer the strength of the texture decreases and finally crystallinity of SmCo5 is lost. In the reversed layer system, Nb on Cr on SmCo5, with decreasing thickness of the Cr spacer layer the epitaxial relationships change from SmCo5(11-20)[0001]//Nb(001)[110] to local SmCo5(11-20) [0001]//Nb(110)[1-11] and the Nb texture changes from the (001)[110] component to a < 110 > fibre. The orientation relationships observed are discussed with regard to elastic strain energy minimization. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim