Optical Study of Metal-Insulator Transition in SmBaCo 2O 6-δ Single Crystal
Abstract
The optical reflectivity spectrum and its temperature dependence were measured on a cleaved (001) surface of SmBaCo2O5.6. With an increase in temperature, the reflectivity below 1 eV increases up to the metal-insulator transition temperature, T MI=360 K, and saturates above T MI. The spectrum of optical conductivity σ(ω) shows large variation in temperature which accompanies the transfer of spectral weight between a broad peak around 3 eV, which can be assigned to the O 2p Co 3d charge-transfer excitation, and the incoherent excitation of carriers below 1 eV. The transferred spectral weight is as large as 0.17 per Co ion, which implies that the effective mass of an electron, m*, can be estimated to be 6m0. The optical gap of 0.2 eV at 20 K is consistent with the resistivity measurement.
- Publication:
-
Journal of the Physical Society of Japan
- Pub Date:
- November 2000
- DOI:
- 10.1143/JPSJ.69.3525
- Bibcode:
- 2000JPSJ...69.3525S