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Susceptibility inhomogeneity and non-Fermi liquid behavior in UCu_{5-x}Pt_x

D. E. MacLaughlin·M. S. Rose·O. O. Bernal·R. H. Heffner·G. J. Nieuwenhuys·R. Chau·M. B. Maple
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Abstract

Transverse-field muSR shifts and relaxation rates have been measured in the non-Fermi liquid (NFL) alloy system UCu_{5-x}Pt_x, x = 1.0, 1.5, and 2.5. At low temperatures the fractional spread in Knight shifts delta K/K approx deltachi/chi is gtrsim 2 for x = 1, but is only half this value for x = 1.5 and 2.5. In a disorder-driven scenario where the NFL behavior is due to a broadly distributed (Kondo or Griffiths-phase cluster) characteristic energy E, our results indicate that delta E/E_{rm av} approx (delta K/K)_{T=0} is similar for UCu_{5-x}Pd_x (x = 1 and 1.5) and UCu_4Pt, but is reduced for UCu_{5-x}Pt_x, x = 1.5 and 2.5. This reduction is due to a marked increase of E with increasing x; the spread delta E is found to be roughly independent of x. Our results correlate with the observed suppression of other NFL anomalies for x > 1 in UCu_{5-x}Pt_x but not in UCu_{5-x}Pd_x, and are further evidence for the importance of disorder in the NFL behavior of both these alloy systems.

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D. E. MacLaughlin, M. S. Rose, O. O. Bernal, R. H. Heffner, G. J. Nieuwenhuys, R. Chau, M. B. Maple. 2005-08-30. Susceptibility inhomogeneity and non-Fermi liquid behavior in UCu_{5-x}Pt_x. https://doi.org/10.1016/j.physb.2005.11.044

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