NMR detection of temperature-dependent magnetic inhomogeneities in URu2Si2

We present Si-29-NMR relaxation and spectral data in URu2Si2. Our echo-decay experiments detect slowly fluctuating magnetic field gradients. In addition, we find that the echo-decay shape (time dependence) varies with temperature T and its rate behaves critically near T-N indicating a correlation between the gradient fluctuations and the transition to small-moment order. T-dependent broadening contributions become visible below similar to 100 K and saturate somewhat above T-N, remaining saturated at lower temperatures. Together, the line width and shift suggest partial lattice distortions below T-N We propose an intrinsic minority phase below T-N and compare our results with one of the current theoretical models. (C) 2000 Elsevier Science B.V. All rights reserved.