NMR and NQR studies of high Tc superconductors

✍ Scribed by W.W. Warren Jr.; R.E. Walstedt; R.F. Bell; G.F. Brennert; R.J. Cava; G.P. Espinosa; J.P. Remeika

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 330 KB
• Volume: 153-155
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(88)90498-4

✦ Synopsis

63'65Cu NMR and NQR studies of YBa2Cu307_ b are described for compositions, 6, of 0.0, 0.3, and 0.9. Spin-lattice relaxation rates in YBazCu307 reveal significantly different electron dynamics at the two Cu sites in both the normal and superconducting states. In YBa2Cu306.7, the relaxation rates of the sites giving a 31 MHz NQR line are dramatically lower (by a factor ~ 1/1500) than in YBa2Cu307 indicating the essential vanishing of mobile carrier density on these sites. In contrast, relaxation at the 22 MHz sites is reduced only about 30 %. Interpretation of these and other NMR and NQR data is discussed in relation to the question of assignment of the NQR lines to the appropriate crystalline sites.