Charge dynamics in the colossal magnetoresistance pyrochlore Tl2Mn2O7 - art. no. 180409

Citation
H. Okamura et al., Charge dynamics in the colossal magnetoresistance pyrochlore Tl2Mn2O7 - art. no. 180409, PHYS REV B, 6418(18), 2001, pp. 0409
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHYSICAL REVIEW B
ISSN journal
0163-1829 → ACNP
Volume
6418
Issue
18
Year of publication
2001
Database
ISI
SICI code
0163-1829(20011101)6418:18<0409:CDITCM>2.0.ZU;2-Z
Abstract
Optical conductivity data [sigma(omega)] of the colossal magnetoresistance (CMR) pyrochlore Tl2Mn2O7 are presented as functions of temperature (T) and external magnetic field (B). Upon cooling and upon applying B near the Cur ie temperature, where the CMR manifests itself, sigma(omega) shows a clear transition from an insulatorlike to a metallic electronic structure as evid enced by the emergence of a pronounced Drude-like component below similar t o0.2 eV. Analyses on the sigma(omega) spectra show that both T- and B-induc ed evolutions of the electronic structure are very similar to each other. a nd that they are universally related to the development of macroscopic magn etization (M). In particular, the effective carrier density obtained from s igma(omega) scales with M-2 over wide ranges of T and B. The contributions to the CMR from the carrier effective mass and scattering time are also eva luated from the data.