Microscopic aspects of cobalt-doping in YBa2Cu3O7−δ : An Y-NMR study

✍ Scribed by W.J. Webster; D.P. Tunstall; P.F. Freeman; J.R. Cooper

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 167 KB
• Volume: 185-189
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)91763-t

✦ Synopsis

Cobalt-doping in YBCO is investigated using Y-89 NMR in aligned samples for the temperatures 150K to 300K.The aim is to understand where the extra susceptibility induced by the doping sits in the lattice. The observed NMR shifts are similar to those induced by oxygen vacancies, but the linewidth broadening is very different. We conclude that (i) the extra susceptibility sits on the chains in the YBCO structure (ii) Cobalt doping, although producing Curie-like terms in the susceptibility, does not lead to the dipolar fields normally associated with local moments and (iii) the hole concentration in the planes becomes disordered.