Magneto-optic spectroscopy of La2/3Sr1/3MnO3films on SrTiO3(1 0 0) and (1 1 0) substrates

La 0.7 Sr 0.3 MnO 3 (LSMO) thin films grown by pulsed laser deposition on SrTiO 3 (STO) substrates with (1 0 0) and (1 1 0) crystallographic orientations are characterized by means of magneto-optic (MO) 'Kerr' spectroscopy at polar and longitudinal magnetizations combined with spectroscopic ellipsometry (SE) in the photon energy range between 1.2 and 4.8 eV. The LSMO film thickness, t , ranges from 10 to 50 nm. Amplitudes in the permittivity tensor spectra, determined from the MO and SE data, depend on t and substrate orientation. The magnetization onset is faster in the films grown on (1 1 0) substrates, probably due to lower strain induced by (1 1 0) substrates. In the films grown on (1 0 0) substrates, the polar and longitudinal MO 'Kerr' spectra can be reasonably explained assuming the diagonal elements of the permittivity tensor to be equal to each other and the off-diagonal elements deduced from the MO polar 'Kerr' spectroscopy. This approach applied to the films grown on (1 1 0) substrates also provides the expected spectral shape; the computed amplitudes are stronger than the observed ones which suggests that the surface morphology affects the permittivity tensor elements in some way. The agreement of the permittivity tensor spectra with those acquired on sintered samples and thick films confirms a perfectly developed perovskite structure even at 10 nm. The study shows that MO spectroscopy and SE can be used for a fast, cheap and efficient diagnostics of the LSMO films in the thickness range relevant for device applications. A low noise level in MO polar 'Kerr' spectra on the thinnest samples ( t ≈ 10 nm) indicates that the presence of the room temperature magnetization and LSMO characteristics in MO spectra can safely be detected in films of t ≈ 5 nm.