Inhomogeneity of charge and spin distribution in CuO sub(2) layers of high-T sub(c) superconductors: NQR/NMR studies of 1-2-3 compounds

• Published in: Journal of superconductivity Vol. 12; no. 1; pp. 113 - 115
• Main Authors: Teplov, M A, Bakharev, O N, Dooglav, A V, Egorov, A V, Mukhamedshin, I R, de Gronckel, H A M, Alloul, H, Mendels, P, Eremina, R M
• Format: Journal Article
• Language: English
• Published: 01.02.1999
• ISSN: 0896-1107

The copper NQR and ZFNMR and thulium NMR are studied in a series of 123 superconductors. It is found that in the aged 60-K superconductors RBa sub(2)Cu sub(3)O sub(6+x) the well known conducting (nonmagnetic) phase co-exists with the magnetically-ordered phase. Both microphases contain two types of inequivalent Cu(2) sites in CuO sub(2) planes. In the conducting phase, these sites differ only in the Cu(2) NQR frequency, whereas in the magnetic one they differ also in the value of hyperfine magnetic fields at Cu(2) nuclei. These differences and the occupation numbers of the two sites are found to be independent of x (in the range x identical with 0.5 divided by 0.6) and of the volume fraction of the magnetic phase. At low temperatures, the nuclear spin-lattice relaxation in both microphases proceeds via magnetic centers formed by hole-doped Cu-O-Cu chain fragments.