Abstract
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 2- xCe xCuO 4-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 2-xSr xCuO 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.
Original language | English |
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Title of host publication | Proceedings of SPIE - The International Society for Optical Engineering |
Editors | I. Bozovic, D. van der Marel |
Pages | 13-23 |
Number of pages | 11 |
Volume | 2696 |
Edition | 1/- |
Publication status | Published - 1996 Dec 1 |
Event | Spectroscopic Studies of Superconductors. Part 2 (of 2) - San Jose, CA, USA, Taiwan Duration: 1996 Jan 29 → 1996 Feb 1 |
Conference
Conference | Spectroscopic Studies of Superconductors. Part 2 (of 2) |
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Country | Taiwan |
City | San Jose, CA, USA |
Period | 1996/01/29 → 1996/02/01 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering