Impact of microstructure on transport properties of nanometric epitaxial SrRuO3 films

We report on structural and magnetotransport properties of SrRuO3 films-grown on SrTiO3-and its dependence on thickness t (4 nmless than or equal totless than or equal to320 nm). At early stages of film growth, a self-ordered finger-like pattern of growth units is formed and gives rise to a prominent in-plane anisotropy of transport properties. We argue that this behavior originates from defective regions formed at grain-merging regions and we show that appropriate annealing allows eliminating these defects. In addition, there is a progressive shift towards a lower temperature of the characteristic feature associated with the onset of the ferromagnetism. Since the films are fully strained, we argue that both effects are not associated to homogeneous cell modifications, but reflects the microstructural disorder concomitant to the island growth observed at early stages of film growth, the resulting stress distribution and the polymorphism of SrRuO3. (C) 2003 American Institute of Physics.