Abstract
Optical conductivity data of the colossal magnetoresistance (CMR) pyrochlore are presented as functions of temperature (T) and external magnetic field Upon cooling and upon applying B near the Curie temperature, where the CMR manifests itself, shows a clear transition from an insulatorlike to a metallic electronic structure as evidenced by the emergence of a pronounced Drude-like component below Analyses on the spectra show that both T- and B-induced evolutions of the electronic structure are very similar to each other, and that they are universally related to the development of macroscopic magnetization In particular, the effective carrier density obtained from scales with over wide ranges of T and B. The contributions to the CMR from the carrier effective mass and scattering time are also evaluated from the data.
- Received 8 May 2001
DOI:https://doi.org/10.1103/PhysRevB.64.180409
©2001 American Physical Society