ANOMALOUS TRANSVERSE RELAXATION OF CU NQR IN YBA2CU3O7-DELTA)

To obtain information on the anomalous peak of Cu NQR transverse relaxation rate found at 35 K in the air annealed YBa2Cu3O7-delta, the carrier concentration was changed by oxygen anneal and Lanthanum substitution for Barium. Carrier injection by the oxygen-anneal has been found to suppress the peak at 35 K, instead, to produce another small peak at 50 K. Five percent substitution of Lanthanum for Barium with the oxygen-anneal, which could reduce the carrier concentration, has reproduced an overall feature found in the air-annealed sample including the peak at 35 K. These observations suggest that the carrier concentration would concern with the anomalous peak, but dynamics of oxygen vacancy in the Cu(1) chain would not do.