Inductive response of polished, single crystal of UPt3

Signore, P.J.C.; Meisel, Mark W.; Brown, Stuart; Fisk, Z.

doi:10.1016/0921-4526(94)91767-1

Cited by 2 publications

(2 citation statements)

References 9 publications

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“…This effect leads the authors to conclude that ''because of the observed sensitivity of the crystal surfaces to mechanical working, a more sophisticated surface preparation would seem necessary to determine a ␦ anisotropy unambiguously.'' Much the same conclusion may be reached from the studies of Signore et al (1994). Another cause for concern is the large value extracted at low temperature: (0)ϭ19 000 Ϯ5000 Å, a factor of 3 larger than expected.…”

Section: Temperature Dependencesupporting

confidence: 57%

“…Indeed, because the magnetic field penetrates only about 1 m into a sample of UPt 3 (0.2 m in YBa 2 Cu 3 O 7 ), a large fraction of that depth must be free of defects which perturb the screening currents, and be representative of the bulk. The surface-sensitive techniques that have been applied to UPt 3 are mainly dc magnetization (see, for example, Gross-Alltag et al, 1991) and ac susceptibility (see, for example, Signore et al, 1994), as well as other high-frequency inductive techniques (see, for example, Shivaram, Gannon, and Hinks, 1990;Bruls, 1995).…”

Section: Temperature Dependencementioning

confidence: 99%

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The superconducting phases ofUPt3

2002

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The heavy-fermion compound UPt 3 is the first compelling example of a superconductor with an order parameter of unconventional symmetry. To this day, it is the only unambiguous case of multiple superconducting phases. Twenty years of experiment and theory on the superconductivity of UPt 3 are reviewed, with the aim of accounting for the multicomponent phase diagram and identifying the superconducting phases. First, the state above the superconducting critical temperature at T c ϭ0.5 K is briefly described: de Haas-van Alphen and other measurements demonstrate that this state is a Fermi liquid, with degeneracy fully achieved at T c . This implies that the usual BCS theory of superconductivity should hold, although the strong magnetic interactions suggest the possibility of an unconventional superconducting order parameter. The role of the weak antiferromagnetic order below T N ϭ5 K in causing phase multiplicity is examined. A comprehensive analysis of which superconducting states are possible is given, and the theoretical basis for each of the main candidates is considered. The behavior of various properties at low temperature (TӶT c ) is reviewed. The experiments clearly indicate the presence of nodes in the superconducting gap function of all three phases. In particular, the low-temperature low-field phase has a gap with a line node in the basal plane and point nodes along the hexagonal c axis. The phase diagram in the magnetic-field-temperature plane has been determined in detail by ultrasound and thermodynamic measurements. Experiments under pressure indicate a coupling between antiferromagnetism and superconductivity and provide additional clues about the order parameter. Theoretically, Ginzburg-Landau theory is the tool that elucidates the phase diagram, while calculations of the temperature and field dependence of physical quantities have been used to compare different order parameters to experiment. On balance, the data point to a two-component order parameter belonging to either the E 1g or the E 2u representation, with degeneracy lifted by a coupling to the symmetry-breaking magnetic order. However, no single theoretical scenario is completely consistent with all the data. The coupling of superconductivity and magnetism may be the weakest link in the current picture of UPt 3 , and full understanding depends on the resolution of this issue.

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Section: Temperature Dependencesupporting

confidence: 57%