Extensive study of the optical spectra for high-temperature superconducting oxides and their related materials from the infrared to the vacuum-ultraviolet energy region

Journal Article · Wed Mar 01 04:00:00 EST 1989 · J. Opt. Soc. Am. B: Opt. Phys.; (United States)

DOI:https://doi.org/10.1364/JOSAB.6.000475· OSTI ID:6228649

Tajima, S; Ishii, H; Nakahashi, T; Takagi, T; Uchida, S; Seki, M; Suga, S; Hidaka, Y; Suzuki, M; Murakami, T; others, and

Optical reflectivity spectra of (La, Sr)/sub 2/CuO/sub 4/ and YBa/sub 2/Cu/sub 3/O/sub y/ have been measured over a wide spectral range as high as 40 eV. Although overall features of the observed spectra are explained well by the results of the available band calculations, the spectra differ significantly from the band calculation in the low-energy region below 5 eV, where the spectrum would presumably be dominated by the transitions between the states involving Cu 3d and O 2p or the charge-transfer (CT) excitation between the O 2p and Cu 3d states. In contrast to the calculation, the observed absorption that probably corresponds to the Cu--O CT process is weak and broad, even for insulating La/sub 2/CuO/sub 4/; thus we cannot firmly determine the CT energy that characterizes the electronic states of these cuprates. To estimate this parameter, the spectra of the cuprates are compared with those for isostructural (La, Sr)/sub 2/MO/sub 4/ (with M = Ni, Co, Fe) as well as with A-site-substituted Nd/sub 2/CuO/sub 4/. From this and also from the measurement of the anisotropy of the spectrum with respect to the Cu--O planes, we estimate the CT energy to be 2--4 eV for both cuprate superconductors. This value is larger than that predicted by the band theory, thus indicating the breakdown or great modification of the band picture in the low-energy region.

• Research Organization: Department of Applied Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113, Japan
• OSTI ID: 6228649
• Journal Information: J. Opt. Soc. Am. B: Opt. Phys.; (United States), Journal Name: J. Opt. Soc. Am. B: Opt. Phys.; (United States) Vol. 6:3; ISSN JOBPD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CERAMICS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRONIC STRUCTURE
INFRARED SPECTRA
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
REFLECTIVITY
SPECTRA
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TYPE-II SUPERCONDUCTORS
ULTRAVIOLET SPECTRA
VISIBLE SPECTRA
YTTRIUM COMPOUNDS
YTTRIUM OXIDES