Indications of non-Fermi liquid behavior at the metamagnetic transition ofUPt3

The specific heat and resistivity of high purity needle crystals and the ma gnetization of a 300 mg piece of a Czochralski-process single crystal of UP t3 aligned so that B perpendicular to c were measured at 0, 18, 19, 20, 22, and 24 T applied fields between 0.5 and 10 K, where B-metamag. approximate to 20 T. The data for C/T, rho, and chi at 18 T and for C/T and rho at 24 T indicate that there is still Fermi liquid behavior at low temperatures fo r B not equal B-metamag. (For B less than or equal to 21 T, chi displays ap parent ferromagnetic behavior.) However, at B-metamag. C/T is found to be p roportional to -log T, or characteristic of non-Fermi liquid (nF1) behavior , over more than a decade in temperature while rho = rho(o) + AT(1.2) at 22 T (0.5 K less than or equal to T less than or equal to 3 K) and chi = chi( o) - aT at 20.5 T (0.5 K less than or equal to T less than or equal to 20 K )-also both characteristic of nF1 behavior. This C/T proportional to -log T behavior is a different nF1 temperature dependence than previously found f or CeRu2Si2 near its B-metamag, where C/T was found to decrease linearly wi th increasing temperature. Thus, although metamagnetism in these, and other , yet to be studied, highly correlated f-electron systems may be a route fo r attaining long range magnetic interactions that prohibit Fermi-liquid beh avior, already the first two systems studied show varying behavior. dHvA da ta at B-metamag for CeRu2Si2 and Shubnikov-de Haas (SdH) data at B-metamag. for UPt3, and theories thereof, will be compared. The SdH data shed light on the present chi(H) data for UPt3 for B > B-metamag. (C) 2000 Published b y Elsevier Science Ltd. All rights reserved.