Variation of electronic structure in La{sub 1{minus}x}Sr{sub x}MnO{sub 3} (0{le}x{le}0.3) as investigated by optical conductivity spectra
- Department of Applied Physics, University of Tokyo, Tokyo 113 (Japan)
Optical conductivity spectra and their variation with temperature and doping level x have been investigated for single crystals of La{sub 1{minus}x}Sr{sub x}MnO{sub 3} (0{le}x{le}0.3). For the low-doped insulating crystal (x=0.1) which shows a ferromagnetic insulating state at low temperature, the spectral weight of the optical conductivity increases only in the inner-gap region around 0.5 eV, but no Drude part emerges due to carrier localization effect. For x{ge}0.17, where the low-temperature ferromagnetic metallic state shows up, the optical conductivity spectrum above T{sub c} is characterized by interband transitions between the exchange-split conduction bands, and it gradually changes into that of intraband excitations below T{sub c}. The energy scale (up to {approx}2 eV) of the spectral weight transfer is determined by the effective Hund{close_quote}s-rule coupling energy. In the metallic phase, low-energy spectra arising from intraband excitations can be sorted into two parts: One is a nearly {omega}-independent broad structure (incoherent part), and the other a sharp coherent Drude peak with anomalously low spectral weight. This can hardly be reconciled with the simple double-exchange theory, but indicates that another degree of freedom (e.g., the orbital ordering and/or electron-lattice interactions) should be taken into account. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 450418
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 7; Other Information: PBD: Feb 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
{ital c}-axis optical spectra and charge dynamics in La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO{sub 4}
Infrared reflectivity of the solid solutions LaNi{sub 1{minus}x}Fe{sub x}O{sub 3} (0.00{le}x{le}1.00)