205 research outputs found
Composite Pairings in Chirally Stabilized Critical Fluids
We study a one-dimensional electron gas in a special antiferromagnetic
environment made by two spin-1/2 Heisenberg chains and the one-dimensional
two-channel Kondo-Heisenberg lattice away from half-filling. These models flow
to an intermediate fixed point which belongs to the universality class of
chirally stabilized liquids. Using a Toulouse point approach, the universal
properties of the models are determined as well as the identification of the
leading instabilities. It is shown that these models exhibit a non-Fermi liquid
behavior with strong enhanced composite pairing correlations.Comment: 4 page
Monte Carlo Calculation of the Spin-Stiffness of the Two-Dimensional Heisenberg Model
Using a collective-mode Monte Carlo method (the Wolff-Swendsen-Wang
algorithm), we compute the spin-stiffness of the two-dimensional classical
Heisenberg model. We show that it is the relevant physical quantity to
investigate the behaviour of the model in the very low temperature range
inaccessible to previous studies based on correlation length and susceptibility
calculations.Comment: 6 pages, latex, 3 postscript figures appended, DIM preprint 93-3
Comment on "Critical properties of highly frustrated pyrochlore antiferromagnets"
We argue that the analysis of Reimers {\it et al.} [ Phys. Rev. B {\bf 45},
7295 (1992)] of their Monte Carlo data on the Heisenberg pyrochlore
antiferromagnet, which suggests a new universality class, is not conclusive. By
re-analysis of their data, we demonstrate asymptotic volume dependence in some
thermodynamic quantities, which suggests the possibility that the transition
may be first order.Comment: 5 pages (RevTex 3.0), 3 figures available upon request, CRPS-93-0
Three-Component Fermi Gas in a one-dimensional Optical Lattice
We investigate the effect of the anisotropy between the s-wave scattering
lengths of a three-component atomic Fermi gas loaded into a one-dimensional
optical lattice. We find four different phases which support trionic
instabilities made of bound states of three fermions. These phases distinguish
themselves by the relative phases between the 2 atomic density waves
fluctuations of the three species. At small enough densities or strong
anisotropies we give further evidences for a decoupling and the stabilization
of more conventional BCS phases. Finally our results are discussed in light of
a recent experiment on Li atoms.Comment: 4 pages, published version. Experimental discussion has been extende
Phases of the generalized two-leg spin ladder: A view from the SU(4) symmetry
The zero-temperature phases of a generalized two-leg spin ladder with
four-spin exchanges are discussed by means of a low-energy field theory
approach starting from an SU(4) quantum critical point. The latter fixed point
is shown to be a rich multicritical point which unifies different competing
dimerized orders and a scalar chirality phase which breaks spontaneously the
time-reversal symmetry. The quantum phase transition between these phases is
governed by spin-singlet fluctuations and belongs to the Luttinger universality
class due to the existence of an exact U(1) self-duality symmetry.Comment: 5 pages, 1 figur
Spontaneous plaquette formation in the SU(4) Spin-Orbital ladder
The low-energy properties of the SU(4) spin-orbital model on a two-leg ladder
are studied by a variety of analytical and numerical techniques. Like in the
case of SU(2) models, there is a singlet-multiplet gap in the spectrum, but the
ground-state is two-fold degenerate. An interpretation in terms of
SU(4)-singlet plaquettes is proposed. The implications for general
two-dimensional lattices are outlined.Comment: 4 pages, 5 Postscript figure
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