Dynamics of the pinned modulation wave in incommensurate bis (4-chlorophenyl) sulfone (BCPS)

We show that both the anomalously huge resonance-frequency dependence of the (35)Cl nuclear quadrupole resonance (NQR) spin-lattice relaxation time in BCPS, reported here for the first time, and its anomalous temperature dependence can be explained by large-scale fluctuations of the pinned modulation wave instead of small-scale fluctuations (phasons and amplitudons). The results were obtained by measuring the laboratory (T(1Q)) and rotating frame (T(1Q,rho)) (35)Cl relaxation times. This is the first time that an effective resonance frequency dependence of the spin-lattice relaxation rate was measured in pure NQR.