Copper NQR and NMR investingations of Metallic but Nonsuperconducting La4BaCu5O13+x

Copper nuclear quadrupole/magnetic resonance (NQR/NMR) has been observed for the pyramidal copper sites in a metallic but nonsuperconducting copper oxide with mixed valence, La 4 BaCu 5 O 13+ x . The electric quadrupole interaction, as well as the NMR shifts, was found to be quite similar to that observed for YBa 2 Cu 3 O 7 , while the nuclear spin-lattice relaxation rate was found to be much lower (1/ T 1 =190 sec -1 at 100 K) compared with that in the normal state of YBa 2 Cu 3 O 7 (1/ T 1 =2300 sec -1 at 100 K). These observations indicate that the behaviors of antiferromagnetic copper spin fluctuations of nonsuperconducting and superconducting oxides are very different.