8 research outputs found
The absence of Ginzburg-Landau mechanism for vestigial order in the normal phase above a two-component superconductor
A two-component superconductor may hypothetically support a vestigial order
phase above its superconducting transition temperature, with rotational or
time-reversal symmetry spontaneously broken while remain non-superconducting.
This has been suggested as an explanation to the observed normal state
nematicity of the nematic superconductor BiSe. We examine the
condition for this vestigial order to occur within Ginzburg-Landau theory with
order parameter fluctuations, on both the nematic and chiral sides of the
theory. Contrary to prior theoretical results, we rule out a large portion of
parameter space for possible vestigial order. We argue that very extreme
anisotropy is one prerequisite for a stable vestigial phase, which is likely
not met in real materials.Comment: 14 pages, 7 figures; the accepted versio
S-matrix approach to quantum gases in the unitary limit II: the three-dimensional case
A new analytic treatment of three-dimensional homogeneous Bose and Fermi
gases in the unitary limit of negative infinite scattering length is presented,
based on the S-matrix approach to statistical mechanics we recently developed.
The unitary limit occurs at a fixed point of the renormalization group with
dynamical exponent z=2 where the S-matrix equals -1. For fermions we find T_c
/T_F is approximately 0.1. For bosons we present evidence that the gas does not
collapse, but rather has a critical point that is a strongly interacting form
of Bose-Einstein condensation. This bosonic critical point occurs at n lambda^3
approximately 1.3 where n is the density and lambda the thermal wavelength,
which is lower than the ideal gas value of 2.61.Comment: 26 pages, 16 figure