Fabrication and optical conductivities of strained epitaxial NaxCoO2 thin films: x=0.5, 0.7

From the spectroscopic ellipsometry analysis, we obtained optical constants as well as optical conductivities for Na0.5CoO2 and Na0.7CoO2 thin films. The energy splitting between eg and a1g increased as a result of the structural strain of the Na0.7CoO2 thin film.