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 magne
tic 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.
We have synthesized and characterized laser-deposited film samples of perovskite BaCrO_{3}, a missing member of the perovskite-chromate family. The BaCrO_{3} films have a substantially larger lattice constant than other chromates, are insulating, and
exhibit weak ferromagnetism likely associated with canted antiferromagnetism. Comparison with the other sister compounds CaCrO_{3} and SrCrO_{3} suggest an anomalous Mott transition where magnetism is independent of whether the compound is metallic or insulating
We studied single-crystalline Pr0.5Sr0.5MnO3 by means of measurements of magnetic susceptibility and specific heat at ambient pressure (P), and electrical resistivity (r) in hydrostatic pressures up to 2 GPa. This material displays ferromagnetic (FM)
order, with Curie temperature TC ~ 255 K. A crystallographic transformation from I4/mcm to Fmmm is accompanied by the onset of antiferromagnetism (AFM), with Neel temperature TN ~ 161 K. The effect of pressure is to lower TC, and raise TN at the approximate rates of -3.2 K/GPa, and 14.2 K/GPa, respectively. Although the value of TN increases with P, due to the enhancement of the superexchange interactions, the AFM-Fmmm state is progressively suppressed, as pressure stabilizes the FM-I4/mcm phase to lower temperatures. The r vs T data suggest that the AFM phase should be completely suppressed near 2.4 GPa.
