Connections between magnetism and superconductivity in UBe sub 13 doped with thorium or boron (invited)
- Los Alamos National Laboratory, Los Alamos, New Mexico (USA)
- ETH, Zurich c/o PSI, CH 5232, Villigen (Switzerland)
- Kamerlingh Onnes Laboratory, 2300 RA Leiden (The Netherlands)
- U. C. Riverside, Riverside (California 92521-04131)
Magnetism and superconductivity appear to be intimately connected in the heavy electron (HE) superconductors. For example, it has been conjectured but not proven that the exchange of antiferromagnetic spin fluctuations are responsible for pairing in HE superconductors. In this paper we review recent results in U{sub 1{minus}{ital x}}Th{sub {ital x}}Be{sub 13}, where specific heat, lower critical field, and zero-field muon-spin-resonance ({mu}SR) measurements reveal another second-order phase transition (below the superconducting transition) to a state which possesses small-moment magnetic correlations for 0.019{le}{ital x}{le}0.043. We present a new phase diagram for (U,Th)Be{sub 13} which indicates that the superconducting and magnetic order parameters are closely coupled. A discussion of the nature of the lower phase is presented, including the consideration of a possible magnetic (time-reversal-violating) superconducting state. When UBe{sub 13} is doped with B (UBe{sub 12.97}B{sub 0.03}) the Kondo temperature is decreased and the specific heat jump at the superconducting transition temperature is significantly enhanced. However, {mu}SR measurements reveal no magnetic signature in UBe{sub 12.97}B{sub 0.03}, unlike the case for Th doping. The correlation between changes in the Kondo temperature and changes in the superconducting properties induced by B doping provide evidence for the importance of magnetic excitations in the superconducting pairing interaction in UBe{sub 13}.
- OSTI ID:
- 5125883
- Journal Information:
- Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 70:10; ISSN 0021-8979; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTINIDE ALLOYS
ALLOYS
BERYLLIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
COMPARATIVE EVALUATIONS
CRITICAL FIELD
DIAGRAMS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EVALUATION
KONDO EFFECT
MAGNETIC FIELDS
MAGNETISM
MUON SPIN RELAXATION
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RELAXATION
SPECIFIC HEAT
SUPERCONDUCTIVITY
THERMODYNAMIC PROPERTIES
THORIUM ADDITIONS
THORIUM ALLOYS
URANIUM ALLOYS