Optical Reflectivity Spectra Measured on Cleaved Surfaces of La_{<b>1</b>-<i><i>x</i></i>}Sr_{<i><i>x</i></i>}MnO_<b>3</b>: Evidence Against Extremely Small Drude Weight

Abstract

Optical reflectivity spectra of La(1-x)Sr(x)MnO(3) (0&lt;=x&lt;=0.30) were measured\non cleavage surfaces of single crystals. The optical conductivity $\\sigma(w) of\nferromagnetic-metal La(0.70)Sr(0.30)MnO(3) is characterized by a Drude-like -\nbut not simple Drude - component with large spectral weight below 1.6 eV, which\nyields a large effective carrier number N*_eff consistent with the results of\nHall coefficient and specific heat measurements. The present result\ndemonstrates that the previous result of "small Drude weight" originates from\nthe damage of the sample surface. The Sr-substitution effect on the electronic\nstructure and the origin of the unconventional $\\sigma(w) are also discussed.\n