Structural and electrical properties of La0.5Sr0.5CoO3 epitaxial films

Abstract

Epitaxial La0.5Sr0.5CoO3 films with very smooth surface morphology were grown on (100) SrTiO3 and (100) MgO substrates by pulsed laser deposition. Scanning tunneling microscopy reveals that the thin film is formed by the coalescence of many aligned square mesas. The growth proceeds from the edges of terraces which are stacked on the mesa. Spiral growth is never observed. Films display an crystallographically isotropic metallic-like electrical conductivity but become semiconductor-like after vacuum annealing. The energy for carrier activation is 0.3 eV. The change of the electrical resistivity of La0.5Sr0.5CoO3 with oxygen pressure at high temperature is much less sensitive than that of YBa2Cu3O7−x.