Magneto-Optical Characterization on the Ferromagnetic-Paramagnetic Transitions in the Composition-Spread Epitaxial Film of Sr1-xCaxRuO3

The composition-spread epitaxial thin film of Sr1-xCaxRuO3 (0.13 <= x <= 0.53) was synthesized by the pulsed laser deposition technique and its x-dependent magnetic properties were probed by the magneto-optical (MO) Kerr spectroscopy. The MO spectra in the energy region of the charge-transfer excitation (O 2p to Ru 4d) are observed to change their spectral intensity critically depending on temperature (T) and x while preserving the spectral shape. The contour mapping of the MO intensity in the x-T plane clarifies the continuous ferromagnetic-to-paramagnetic phase change with increase of not only T but also x, revealing the quantum-critical point around x = 0.5. (C) 2008 The Japan Society of Applied Physics