corner
corner
APS » Journals » Phys. Rev. B » Volume 58 » Issue 24
< Previous Article | Next Article >

Phys. Rev. B 58, 16093–16102 (1998)

Optical conductivity of manganites: Crossover from Jahn-Teller small polaron to coherent transport in the ferromagnetic state

Download: PDF (325 kB) Buy this article Export: BibTeX or EndNote (RIS)

M. Quijada* and J. Černe
Laboratory for Physical Sciences, College Park, Maryland 20740

J. R. Simpson
Materials Research Laboratory, Department of Physics, University of Maryland, College Park, Maryland 20742

H. D. Drew
Laboratory for Physical Sciences, College Park, Maryland 20740
Materials Research Laboratory, Department of Physics, University of Maryland, College Park, Maryland 20742

K. H. Ahn and A. J. Millis
Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218

R. Shreekala, R. Ramesh, M. Rajeswari, and T. Venkatesan
Materials Research Laboratory, Department of Physics, University of Maryland, College Park, Maryland 20742

Received 16 March 1998; published in the issue dated 15 December 1998

We report on the optical properties of the hole-doped manganites Nd0.7Sr0.3MnO3, La0.7Ca0.3MnO3, and La0.7Sr0.3MnO3. The low-energy optical conductivity in the paramagnetic-insulating state of these materials is characterized by a broad maximum near 1 eV. This feature shifts to lower energy and grows in optical oscillator strength as the temperature is lowered into the ferromagnetic state. It remains identifiable well below Tc and transforms eventually into a Drude-like response. This optical behavior and the activated transport in the paramagnetic state of these materials are consistent with a Jahn-Teller small polaron. The optical spectra and oscillator strength changes compare well with models that include both double exchange and the dynamic Jahn-Teller effect in the description of the electronic structure.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.58.16093
DOI:
10.1103/PhysRevB.58.16093
PACS:
75.70.Pa, 78.20.-e, 78.30.-j

*Present address: Code 551, Goddard Space Flight Center, Greenbelt, MD 20771.

 
< Previous Article | Next Article >