Optical Spectra Measured on Cleaved Surfaces of Double‐Exchange Ferromagnet La1—xSrxMnO3

Optical reflectivity spectra were measured on cleaved surfaces of La1-xSrxMnO3 single crystals (x=0.175, T_C=283 K) over a temperature range 10-295 K. The optical conductivity $sigma(\omega)$ shows, keeping single-component nature, incoherent-to-coherent crossover with increase of electrical conductivity. The $\sigma(\omega)$ spectrum of low-temperature ferromagnetic-metallic phase (10 K) exhibits a pronounced Drude-like component with large spectral weight, contrary to the previous result. The present result indicates that the optical spectrum of the manganites is sensitive to condition of sample surfaces.