Nuclear magnetic resonance in the superconducting states of two heavy fermion superconductors, CeCu/sub 2/Si/sub 2/ and UBe/sub 13/

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6856710

Tien, C

Nuclear magnetic resonance (NMR) experiments were carried out in two heavy fermion superconductors, CeCu/sub 2/Si/sub 2/ and U/sub 1-x/Th/sub x/Be/sub 13/ (x = 0,0.0331). The unusual normal state and superconducting state behavior of CeCu/sub 2/Si/sub 2/ and UBe/sub 13/ has recently been discovered. Both compounds exhibit enormous values of the normal state low temperature magnetic susceptibility chi and the linear specific heat coefficient ..gamma... Standard analyses of chi and ..gamma.. results in a two order of magnitude enhancement of the conduction electron mass, but the ratio chi/..gamma.. retains a value appropriate to a free-electron gas. It is of interest to obtain as much microscopic information as possible. In one of the CeCu/sub 2/Si/sub 2/ superconducting specimens, the observed temperature dependence of the spin-lattice relaxation rate 1/T/sub 1/ (T) is consistent with a conventional quasi-particle excitation spectrum below the superconducting transition temperature T/sub c/. In the other superconducting CeCu/sub 2/Si/sub 2/ sample, the nuclear spin-lattice relaxation rate decreases drastically just below T/sub c/ without the apparent enhancement observed in the first sample. The spin lattice relaxation rate in UBe/sub 13/ varies approximately as T/sup 3/ well below the transition temperature T/sub c/., This behavior is consistent with a class of anisotropic pairing models for which the superconducting gap vanishes along lines on the Fermi surface.

• Research Organization: California Univ., Riverside (USA)
• OSTI ID: 6856710
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
360603* -- Materials-- Properties
ACTINIDE ALLOYS
ALLOYS
BERYLLIUM ALLOYS
CERIUM ALLOYS
COPPER ALLOYS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON GAS
FLUIDS
GASES
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
RELAXATION
RESONANCE
SILICON ALLOYS
SPIN-LATTICE RELAXATION
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
URANIUM ALLOYS