Doping and charge-carrier density effects in the cuprate superconductors

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:538185

Tanner, D B; Yoon, Y D; Zibold, A ^[1]

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1. Univ. of Florida, Gainesville, FL (United States). Dept. of Physics; and others

The undoped phases of the copper-oxide materials are antiferromagnetic insulators, with a gap of 1.5--2 eV. Infrared spectroscopy of these compounds reveals weak absorption, possibly of magnetic origin, in this gap. When the materials are doped, oscillator strength is removed from the charge transfer band. This oscillator strength moves to low frequency, to become midinfrared and free carrier absorption. A systematic study of the electron-doped Nd{sub 2{minus}x}Ce{sub x}CuO{sub 4{minus}y} system reveals that the growth of low-frequency oscillator strength with doping concentration x is twice as rapid as in the case of hole-doped materials, such as La{sub 2{minus}x}Sr{sub x}CuO{sub 4}. This behavior is in accord with electronic structure models based on the 3-band Hubbard model and inconsistent with one-band behavior. However, an anomaly occurs for samples which are doped to the critical concentration for superconductivity; these have a greater than expected free-carrier concentration and weaker charge-transfer bands. 48 refs., 6 figs., 1 tab.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States)
• OSTI ID: 538185
• Report Number(s): CONF-960163--; ISBN 0-8194-2070-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARRIER DENSITY
CERIUM OXIDES
CHARGE CARRIERS
COPPER OXIDES
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
HIGH-TC SUPERCONDUCTORS
INFRARED SPECTRA
NEODYMIUM OXIDES
OPTICAL PROPERTIES
OSCILLATOR STRENGTHS