Magnetic resonance (muSR and NMR) studies of f-electron non-Fermi-liquid (NFL) materials give clear evidence that structural disorder is a major factor in NFL behavior. Longitudinal-field muSR relaxation measurements at low fields reveal a wide distribution of muon relaxation rates and divergences in the frequency dependence of spin correlation functions in the NFL systems UCu_{5-x}Pd_x and CePtSi_{1-x}Ge_x. These divergences seem to be due to slow dynamics associated with quantum spin-glass behavior, rather than quantum criticality as in a uniform system, for two reasons: the observed strong inhomogeneity in the muon relaxation rate, and the strong and frequency-dependent low-frequency fluctuation observed in U(Cu,Pd)_5 and CePt(Si,Ge). In the NFL materials CeCu_{5.9}Au_{0.1}, Ce(Ru_{0.5}Rh_{0.5})_2Si_2, CeNi_2Ge_2, and YbRh_2Si_2 the low-frequency weight of the spin fluctuation spectrum is much weaker than in the disordered NFL systems.
@article{arxiv.cond-mat/0207461,
title = {muSR and NMR in f-electron non-Fermi liquid materials},
author = {D. E. MacLaughlin and M. S. Rose and Ben-Li Young and O. O. Bernal and R. H. Heffner and G. D. Morris and K. Ishida and G. J. Nieuwenhuys and J. E. Sonier},
journal= {arXiv preprint arXiv:cond-mat/0207461},
year = {2009}
}
Comments
10 pages, 4 figures. To be published in proceedings of muSR2002 (Physica B)