Abstract
Thin films of the double perovskite La2CoMnO6 have been grown epitaxially on (001)-oriented SrTiO3 substrates at different oxygen background pressures (1 - 600 mTorr) using the pulsed laser deposition (PLD) technique. Scanning transmission electron microscopy (STEM) results confirm that the films grow epitaxially with a high degree of crystalline order, but show the presence of twin microdomains. The oxygen pressure during growth plays an essential role in determining the magnetic properties of the films. Magnetization measurements reveal the existence of two distinct ferromagnetic phases, the relative fraction of which varies as a function of oxygen pressure. Interpretation of the formation of the two phases is based on the hypothesis that introduction of high-spin Mn3+ from the formation of oxygen vacancies results in the concurrent formation of additional Mn3+ and intermediate-spin Co3+ at neighboring sites.