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Proceedings Paper

Effects of Ni doping on the optical conductivity of YBa2Cu3O6.95
Author(s): Christopher C. Homes; Q. Song; B. P. Clayman; D. A. Bonn; Ruixing Liang; Walter N. Hardy
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Paper Abstract

The optical conductivity ((sigma) 1) of twinned and untwinned single crystals of YBa2(Cu1-xNix)3O6.95 has been studied using infrared reflectance spectroscopy for x equals 0, 0.75 and 1.4% ('pure,' 'light' and 'heavily' doped). The optical properties have been calculated from a Kramers-Kronig analysis of the reflectance. Nickel acts as a point defect scatterer in the planes, but has only a small effect on Tc. (At the heaviest Ni doping, Tc is only suppressed by approximately equal to 4 K). In the pure, twinned samples for T very much less than Tc, there is a narrow, 'Drude'-like band at low frequency; the conductivity is observed to drop to a minimum of approximately equal to 1000 (Omega) -1 cm-1 at approximately equal to 500 cm-1 before gradually rising to join a temperature-independent midinfrared band. In the heavily- doped sample, there is a large amount of low-frequency residual conductivity; at 6 K some of the residual conductivity has been suppressed and a shoulder in (sigma) 1 is visible at approximately equal to 300 cm-1. In the lightly-doped sample, the approximately equal to 300 cm-1 shoulder is visible already at 12 K. However, in the same detwinned sample, the shoulder in (sigma) 1 is observed only for E (parallel) b, and is present in the normal state indicating that this feature is associated with the chains, and is not related to the superconductivity in these materials. The origin of this feature is discussed, and it is proposed that the shoulder at approximately equal to 300 cm-1 may be related to the pseudogap observed along the c axis in the oxygen-underdoped materials.

Paper Details

Date Published: 10 June 1996
PDF: 6 pages
Proc. SPIE 2696, Spectroscopic Studies of Superconductors, (10 June 1996); doi: 10.1117/12.241795
Show Author Affiliations
Christopher C. Homes, Simon Fraser Univ. (Canada)
Q. Song, Simon Fraser Univ. (Canada)
B. P. Clayman, Simon Fraser Univ. (Canada)
D. A. Bonn, Univ. of British Columbia (Canada)
Ruixing Liang, Univ. of British Columbia (Canada)
Walter N. Hardy, Univ. of British Columbia (Canada)

Published in SPIE Proceedings Vol. 2696:
Spectroscopic Studies of Superconductors
Ivan Bozovic; Dirk van der Marel, Editor(s)

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