th  - 1988 - 51st ENC Conference

TUE Eve 8-50 } Cu NQR OF YBa2Cu30 x WITH VARYING OXYGEN CONTENT:
A. J. Vega*, W. E. Farneth, R. K. Bordia, and E. M. McCarron, Central
Research and Development Department, E. I. du Pont de Nemours and
Company, Experimental Station, Wilmington, Delaware 19898~
The 63Cu and 65Cu NQR spectra of YBa2Cu30 x show a strong dependence
on the oxygen content when x is varied from 6 to 7. For x=7 two
signals are observed at room temperature. The room-temperature
signals generally consist of a short-T 1 (< 1 ms) and a long-T 1
component (~ 100 ms). The relative intensity of the short-T 1
component gradually decreases from 100% to 0% when x is decreased
from 7.0 to 6.0. In addition, the line shapes of the two T 1
components are strongly dependent on the oxygen content. While the
short Tl's are attributed to a Korringa-type relaxation mechanism
involving the conduction electrons, it may be assumed that the Cu
sites with the longer T 1 values are not directly associated with the
conduction process. The NQR data can thus be used to help interpret
the strong dependence of T c on the oxygen content of these
superconducting materials.
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