Upper critical magnetic field of heavy-electron superconductors
The upper critical magnetic fields H/sub c2/(T) of the heavy electron superconductors UBe/sub 13/, UPt/sub 3/ and URu/sub 2/Si/sub 2/ were investigated. In addition, H/sub c2/(T) of the pseudobinary system (U/sub 1-x/Th/sub x/)Be/sub 13/ with 0 less than or equal to x less than or equal to 0.03 was determined. As a part of a research for other heavy electron systems, the physical properties of the U-compounds UCo, URu/sub 3/, U/sub 3/X (X = Ir, Si and Os), U/sub 2/X (X = transition metals) and UMSi/sub x/ (x = 1,2 and M = Ru, Rh, Os, Ir) were characterized. H/sub c2/(T) data for UBe/sub 13/ reveal an initial slope (dH/sub c2//dT)/sub T/sub c// of 420 kOe/K, the highest value that has ever been reported for any bulk superconductor. At lower temperature, H/sub c2/ increases linearly with decreasing temperature with a slope of -91 kOe/K for a monocrystalline sample, and with slight upturned for a polycrystalline sample. Substitution of Th impurities for U (Th concentration less than or equal to 3 at. %) in UBe/sub 13/ generally decreases the superconducting transition temperature T/sub c/ but leaves the value of (-dH/sub c2//dT)/sub T/sub c// and the shape of H/sub c2/(T) unchanged. Transport, thermal, and magnetic measurements on a polycrystalline URu/sub 2/Si/sub 2/ sample indicate that this compounds becomes a super-conductor with T/sub c/ approx. 1.5 K. A phase transition that involves the removing of an energy gap of approx. 11 meV opened over a portion of the Fermi surface was observed at T approx. 17.2 K.
- Research Organization:
- California Univ., San Diego (USA)
- OSTI ID:
- 6512256
- Country of Publication:
- United States
- Language:
- English
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