No abstract

The oxygen content dependence of 63 Cu NQR at the Cu(l) site and proton NMR have been measured in the antiferromagnetic phase of powdered samples of hydrogen-doped YBa 2 Cu 3 0 6+x .H v (0.07 < JC < 0.17 and y » 1) from 4.2 to 90 K. The spectrum of 1 H NMR is a single line and the line width increases below 15 Kdue to magnetic interactions. The enhancements of Tf 1 and 7^1 of 63 Cu(l)NQR occur around 35 and 15 K, respectively. These enhancements increase with increasing oxygen concentration. The maximum values of Tf 1 and T^ for the sample with x = 0.17 reach 200 sec -1 and more than 7 msec -1 , respectively. The predominant source for the relaxation mechanism of 63 Cu(l) NQR and the line broadening of 'H NMR are found to be the fluctuating magnetic field due to the staggered Cu 2+ moments.

The spin-lattice and spin-spin relaxation times T t and T 2 of 35 C1 NQR were measured for the high (I) and low (II) temperature phases of 4-chlorobenzyl alcohol in the range 50< T/K <338 (transition and melting points: 236 and 343.5 K, respectively). In phase II the T x behavior in the range 50< T/K<90 can be explained by lattice vibrations and that in the range 90260 K is explainable by another reorientation with £ a %4.7 kJ/mol. The T, vs. T curves revealed that in both phases the crystal dynamics is anomalous in the vicinity of the transition temperature. Lattice defects accumulated in phases I and II by the phase transition were found to be responsible for the extremely short inverse line width parameters (7^).