TEMPERATURE-DEPENDENCE OF QUADRUPOLE INTERACTION IN HIGH-TC SUPERCONDUCTOR YBA2(CU0.9AG0.1)3O7-DELTA

The temperature dependence of quadrupole interaction in high-Tc superconductor YBa2(Cu0.9Ag0.1)3 O7-δ has been measured over temperature range 77-298K by using the perturbed angular correlation (PAC) spectroscopy. Two static electric field gradients (EFGs), the non-axially symmetric and the axial symmetric EFGs, have been derived from each time differential perturbed angular correlation (TDPAC) spectrum taken at a specific temperature between 114K and 298K, they are assigned to Cu(1) and Cu(2) sites in the oxygen-deficient perovskite structure respectively. The non-axially symmetric EFG shows a sudden transition around 90K. Nuclear relaxation phenomena are observed from the TDPAC spectra simultaneously. From the behavior of temperature dependence of normal state relaxation, we make the suggestion that the relaxation is magnetic in nature, and it seems that any dynamical field in the interactions due to particle motion has to be excluded. © 1990.