Precise Measurement of Optical Reflectivity Spectra Using Defect-Free Surface of La1−xSrxMnO3: Evidence Against Extremely Small Drude Weight

Optical reflectivity spectra of La1−xSrxMnO3 (0≤x≤0.30) were measured on cleavage surfaces of single crystals. The optical conductivity σ(ω) of ferromagnetic-metal La0.70Sr0.30MnO3 is characterized by a Drude-like − but not simple-Drude − component with large spectral weight below ∼1.6 eV, which yields a large effective carrier number N eff consistent with the results of Hall coefficient and specific heat measurements. The present result demonstrates that the previous result of “small Drude weight” originates from the damage of the sample surface. The Sr-substitution effect on the electronic structure and the origin of the unconventional σ(ω) are also discussed. PACS numbers: 71.27.+a, 71.30.+h, 78.30.−j Typeset using REVTEX