Relaxation-time enhancement in the heavy-fermion systems CePd/sub 3/ and UPt/sub 3/

Journal Article · Wed Feb 01 00:00:00 EST 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.2377· OSTI ID:6485239

Awasthi, A M; Beyermann, W P; Carini, J P; Gruener, G

The frequency dependence of the electrical conductivity was measured at microwave- and millimeter-wave frequencies in the heavy-fermion materials CePd/sub 3/ and UPt/sub 3/. Although the conductivity is independent of the frequency at high temperatures, a substantial deviation from the dc conductivity develops in the low-temperature, ''coherent'' regime. The observed dependence on frequency agrees with a Drude expression sigma/sub 1/(..omega..) = sigma/sub d//sub c//(1+..omega../sup 2/tau/sup *//sup 2/), incorporating a renormalized relaxation time tau/sup */ typically around 10/sup -12/ s. From tau/sup */ and the measured sigma/sub dc/, the renormalized plasma frequency, ..omega../sub p//sup */ = (sigma/sub d//sub c//epsilon/sub 0/tau/sup */)/sup 1/2/ is evaluated. By comparison of ..omega../sub p//sup */ with the plasma frequency obtained at optical frequencies, where renormalization effects do not occur, an enhanced mass is extracted. Similar results are found by comparison of ..omega../sub p//sup */ with the linear specific-heat coefficient. The enhanced relaxation time is approximately given by the expression tau/sup *//tau = m/sup *//m/sub e/, where tau and m/sub e/ refer to the unrenormalized quantities, supporting the conjectures of Varma and Fukuyama, and the theoretical models advanced by Millis and co-workers, Auerbach and co-workers, and Coleman. An internally consistent analysis of sigma(..omega..) in terms of an enhanced relaxation time also suggests that a frequency-dependent density of states does not play a dominant role in the frequency-dependent response measured in the millimeter-wave spectral range.

• Research Organization: Department of Physics and Solid State Science Center, University of California, Los Angeles, California 90024
• OSTI ID: 6485239
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 39:4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERIUM ALLOYS
ELECTRIC CONDUCTIVITY
PALLADIUM ALLOYS
PLATINUM ALLOYS
URANIUM ALLOYS
FREQUENCY DEPENDENCE
RELAXATION TIME
RENORMALIZATION
ACTINIDE ALLOYS
ALLOYS
ELECTRICAL PROPERTIES
PHYSICAL PROPERTIES
PLATINUM METAL ALLOYS
RARE EARTH ALLOYS
360104* - Metals & Alloys- Physical Properties