Heavy fermions in Kondo lattice compounds (invited)

Journal Article · Mon Apr 15 04:00:00 EST 1985 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.335212· OSTI ID:5785033

Steglich, F; Rauchschwalbe, U; Gottwick, U; Mayer, H M; Sparn, G; Grewe, N; Poppe, U; Franse, J J.M.

Even in the absence of both magnetic order and superconductivity, Ce-based Kondo lattice systems show distinct anomalies in the low-temperature specific heat and thermopower. These features can be understood, in the frame of a microscopic treatment of the asymmetric Anderson model, by taking into account the periodicity of the Ce sites. A substantial variation in the observed phenomena between CeAl/sub 3/ and normal (n) state CeCu/sub 2/Si/sub 2/ on the one hand as well as CeRu/sub 2/Si/sub 2/ and CeCu/sub 6/ on the other highlight the importance of realistic band structure calculations for the quasiparticles (''heavy fermions'') in these different compounds. The temperature dependence of the upper critical magnetic field B/sub c//sub 2/(T) for the heavy-fermion superconductor CeCu/sub 2/Si/sub 2/ (T/sub c/approx. =0.6 K) shows a flat maximum at approx.0.2 T/sub c/, which is ascribed to coherence-derived structure in the n-state quasiparticle density of states. A dc Josephson effect with a critical pair current of ordinary size is observed for the first time on a weak link between CeCu/sub 2/Si/sub 2/ and Al. This proves that CeCu/sub 2/Si/sub 2/ is a superconductor with dominant spin-singlet pairing. No Josephson effect can be found, however, between heavy-fermion superconducting UPt/sub 3/ and Al, Nb, or UPt/sub 3/ as counterelectrodes, in accord with a possible anisotropic (L > or = 1, S = 0 or 1) pairing in UPt/sub 3/.

• Research Organization: Institut fuer Festkoerperphysik, Technische Hochschule Darmstadt, D-6100 Darmstadt, Federal Republic of Germany
• OSTI ID: 5785033
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 57:8; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTINIDE ALLOYS
ALLOYS
ALUMINIUM ALLOYS
CERIUM ALLOYS
COPPER ALLOYS
CRITICAL FIELD
CRYSTAL MODELS
ELECTRIC CONDUCTIVITY
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ELECTRICITY
JOSEPHSON JUNCTIONS
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KONDO EFFECT
MAGNETIC FIELDS
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
RARE EARTH ALLOYS
RUTHENIUM ALLOYS
SILICON ALLOYS
SPECIFIC HEAT
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
THERMOELECTRICITY
URANIUM ALLOYS