CMT141
Chiral Phases of Superfluid 3He in an Anisotropic Medium
- Author(s):
J. A. Sauls
- Address: Department of Physics & Astronomy, Northwestern University, Evanston, IL 60208
- Date: July 29, 2013
- Journal:
Phys. Rev. B 88, 214503 (2013)
[DOI]
- Abstract:
I report theoretical analysis and predictions for the equilibrium phases of superfluid 3He
infused into
a low-density, homogeneous uniaxial aerogel. Ginzburg-Landau (GL) theory for a class of equal-spin-pairing
(ESP) states in a medium with uniaxial anisotropy is developed and used to analyze recent experiments on
uniaxially strained aerogels. For 3He in an axially "stretched" aerogel GL theory predicts a
transition
from normal liquid into a chiral ABM phase at
Tc1 in which the chirality axis, l, is aligned along the
strain axis. This orbitally aligned state, is protected from random fluctuations in the anisotropy direction,
has a positive NMR frequency shift, a sharp NMR resonance line and is identified with the high-temperature
ESP-1 phase of superfluid 3He in axially stretched aerogel. A second transition into a biaxial
phase is
predicted to onset at a slightly lower temperature, Tc2 < Tc1. This
phase is an ESP state, breaks
time-reversal symmetry, and is defined by an orbital order parameter that spontaneously breaks axial
rotation symmetry. This transition is driven by the coupling of an axially aligned 1D ``polar'' order
parameter to the two time-reversed 2D axial ABM states. The biaxial phase has a continuous degeneracy
associated with the projection of its chiral axis in the plane normal to the anisotropy axis. Theoretical
predictions for the NMR frequency shifts of the biaxial phase provide an identification of the ESP-2 as
the biaxial state, partially disordered by random anisotropy (Larkin-Imry-Ma effect). The ``width'' of the
jump in the NMR frequency shift at Tc2 provides an estimate of the orbital domain size,
ξLIM ≈ 5 μ-m at 18 bar.
- Comment: 15 pages, 6 figures
- Eprint:
[arXiv]
[PDF]
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