Theory of Equilibrium Flux Lattice inUPt3under Magnetic Field Parallel to Hexagonal Crystal Axis

Abstract

We investigate Abrikosov lattice structures in the unconventional superconductor UPt (3) under magnetic field parallel to the hexagonal crystal axis. Only the two-dimensional E2 superconducting state among the many other states of different symmetry is compatible with the recent observation [A. Huxley et al., Nature (London) 406, 160 (2000)] of the flux lattice in the A phase misaligned with crystallographic directions. It is shown that the inequality of the London penetration depths in the basal plane directions resulting from the superposition of hexagonal crystal and superconducting state anisotropies leads for E2 to a slightly distorted triangular flux lattice.

London Theory for Superconducting Phase Transitions in External Magnetic Fields: Application toUPt3

“…[5] for an overview). However, it appears that only those theories in which a doubly degenerate order parameter has its degeneracy broken by a symmetry breaking field are consistent with the recent SANS measurements of Huxley et al [6,7]. The two most popular variants of this class of models are based on the E 2u and the E 1g REPS of the hexagonal point group [5,8].…”

“…This problem has been addressed recently by Champel and Mineev in Ref. [7]. The result of this study is that the vortex lattice will be a stretched hexagonal lattice near H c1 .…”

Superconducting phases off-electron compounds

“…For instance, in a recent small angle neutron scattering study the magnetic field dependence of the flux line lattice has been established. The upshot of this study is that the three superconducting phases belong to the E 2u symmetry (see also (Champel and Mineev, 2001) for theoretical considerations on the flux line lattice). For an extended review and critical discussion of the various theoretical scenarios we refer to (Joynt and Taillefer, 2002).…”

Anomalous Field-Angle Dependence of the Specific Heat of Heavy-Fermion Superconductor UPt3

“…On theoretical grounds, various multi-component order parameters have been proposed so far. [1,15,16) One of the plausible scenarios is the E 2u model with spin-triplet pairing involving the SC order parameters k z (k small-angle neutron scattering [17,18) and junction experiments [19,20) performed in the A and B phases. However, a conflicting scenario, the spin-triplet E 1u model with the order parameters k x (5k 2 z − 1) and k y (5k 2 z − 1) has recently been proposed on the basis of the results of field-angle-resolved thermal-conductivity κ(φ) measurements performed in the B and C phases; [21,22) under a magnetic field H rotated around the c axis, κ(φ) exhibits a twofold oscillation at 50 mK only in the C phase.…”