Optical phase diagram of perovskite colossal magnetoresistance manganites near half doping

I. Kézsmárki, Y. Tomioka, S. Miyasaka, L. Demkó, Y. Okimoto, Y. Tokura

Research output: Contribution to journalArticle

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Abstract

We present a systematic optical study for a bandwidth-controlled series of nearly half-doped colossal magnetoresistive manganites RE0.55 AE0.45 Mn O3 (RE and AE being rare earth and alkaline earth ions, respectively) under the presence of quenched disorder over a broad temperature region T=10-800 K. The ground state of the compounds ranges from the charge and orbital ordered insulator through the spin glass to the ferromagnetic metal. The enhanced phase fluctuations, namely, the short-range charge and orbital correlations, dominate the paramagnetic region of the phase diagram above all the ground-state phases. This paramagnetic region is characterized by a full-gap to pseudogap crossover toward elevated temperatures where a broad low-energy electronic structure appears in the conductivity spectra over a large variation of the bandwidth. This pseudogap state with local correlations is robust against thermal fluctuations at least up to T=800 K. For a small bandwidth, the onset of the long-range charge order is accompanied by an instantaneous increase of the gap. The emergence of the ferromagnetic state is manifested in the optical spectra as a first-order insulator to a metal transition for compounds with a moderate bandwidth, while it becomes a second-order transition on the larger bandwidth side. An unusually large scattering rate of the metallic carriers is observed in the ferromagnetic state, which is attributed to orbital correlation effects.

Original languageEnglish
Article number075117
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume77
Issue number7
DOIs
Publication statusPublished - Feb 15 2008

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Colossal magnetoresistance
Manganites
Perovskite
Phase diagrams
Doping (additives)
phase diagrams
bandwidth
Bandwidth
orbitals
Ground state
insulators
Ferromagnetic materials
Spin glass
ground state
spin glass
Rare earths
Electronic structure
Transition metals
optical spectrum
crossovers

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Optical phase diagram of perovskite colossal magnetoresistance manganites near half doping. / Kézsmárki, I.; Tomioka, Y.; Miyasaka, S.; Demkó, L.; Okimoto, Y.; Tokura, Y.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 77, No. 7, 075117, 15.02.2008.

Research output: Contribution to journalArticle

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