  Using pulsed laser deposition and a unique fast quenching method, we have
prepared SrCoOx epitaxial films on SiTiO3 substrates. As electrochemical
oxidation increases the oxygen content from x = 2.75 to 3.0, the films tend to
favor the discrete magnetic phases seen in bulk samples for the homologous
series SrCoO(3-n/8) (n = 0, 1, 2). Unlike bulk samples, 200nm thick films
remain single phase throughout the oxidation cycle. 300 nm films can show two
simultaneous phases during deoxidation. These results are attributed to finite
thickness effects and imply the formation of ordered regions larger than
approximately 300 nm.
