465 research outputs found
Coordinate Representation of the Two-Spinon wavefunction and Spinon Interaction
By deriving and studying the coordinate representation for the two-spinon
wavefunction, we show that spinon excitations in the Haldane-Shastry model
interact. The interaction is given by a short-range attraction and causes a
resonant enhancement in the two-spinon wavefunction at short separations
between the spinons. We express the spin susceptibility for a finite lattice in
terms of the resonant enhancement, given by the two-spinon wavefunction at zero
separation. In the thermodynamic limit, the spinon attraction turns into the
square-root divergence in the dynamical spin susceptibility.Comment: 19 pages, 5 .eps figure
Breakdown of Luttinger liquid state in one-dimensional frustrated spinless fermion model
Haldane hypothesis about the universality of Luttinger liquid (LL) behavior
in conducting one-dimensional (1D) fermion systems is checked numerically for
spinless fermion model with next-nearest-neighbor interactions. It is shown
that for large enough interactions the ground state can be gapless (metallic)
due to frustrations but not be LL. The exponents of correlation functions for
this unusual conducting state are found numerically by finite-size method.Comment: 3 pages, 4 figures, RevTe
Thermodynamics of an one-dimensional ideal gas with fractional exclusion statistics
We show that the particles in the Calogero-Sutherland Model obey fractional
exclusion statistics as defined by Haldane. We construct anyon number densities
and derive the energy distribution function. We show that the partition
function factorizes in the form characteristic of an ideal gas. The virial
expansion is exactly computable and interestingly it is only the second virial
coefficient that encodes the statistics information.Comment: 10pp, REVTE
Superconductivity from doping a spin liquid insulator: a simple one-dimensional example
We study the phase diagram of a one-dimensional Hubbard model where, in
addition to the standard nearest neighbor hopping , we also include a
next-to-nearest neighbor hopping . For strong enough on-site repulsion,
this model has a transition at half filling from a magnetic insulator with
gapless spin excitations at small to a dimerized insulator with a spin
gap at larger . We show that upon doping this model exhibits quite
interesting features, which include the presence of a metallic phase with a
spin gap and dominant superconducting fluctuations, in spite of the repulsive
interaction. More interestingly, we find that this superconducting phase can be
reached upon hole doping the magnetic insulator. The connections between this
model and the two chain models, recently object of intensive investigations,
are also discussed.Comment: 19 pages, plain LaTex using RevTex, 7 postscript figures Modified
version which excludes some LaTex commands giving problems for the previous
versio
Wigner Crystals in the lowest Landau level at low filling factors
We report on results of finite-size numerical studies of partially filled
lowest Landau level at low electron filling factors. We find convincing
evidence suggesting that electrons form Wigner Crystals at sufficiently low
filling factors, and the critical filling factor is close to 1/7. At nu=1/7 we
find the system undergoes a phase transition from Wigner Crystal to the
incompressible Laughlin state when the short-range part of the Coulomb
interaction is modified slightly. This transition is either continuous or very
weakly first order.Comment: 5 papges RevTex with 8 eps figures embedded in the tex
The geometry of antiferromagnetic spin chains
We construct spin chains that describe relativistic sigma-models in the
continuum limit, using symplectic geometry as a main tool. The target space can
be an arbitrary complex flag manifold, and we find universal expressions for
the metric and theta-term.Comment: 31 pages, 3 figure
Haldane's Fractional Exclusion Statistics for Multicomponent Systems
The idea of fractional exclusion statistics proposed by Haldane is applied to
systems with internal degrees of freedom, and its thermodynamics is examined.
In case of one dimension, various bulk quantities calculated show that the
critical behavior of such systems can be described by conformal field
theories and conformal weights are completely characterized by statistical
interactions. It is also found that statistical interactions have intimate
relationship with a topological order matrix in Chern-Simons theory for the
fractional quantum Hall effect.Comment: 12 pages, Revtex, preprint YITP/K-107
Integral Representations of the Macdonald Symmetric Functions
Multiple-integral representations of the (skew-)Macdonald symmetric functions
are obtained. Some bosonization schemes for the integral representations are
also constructed.Comment: LaTex 21page
Spin Stiffness of Mesoscopic Quantum Antiferromagnets
We study the spin stiffness of a one-dimensional quantum antiferromagnet in
the whole range of system sizes and temperatures . We show that for
integer and half-odd integer spin case the stiffness differs fundamentally in
its and dependence, and that in the latter case the stiffness exhibits
a striking dependence on the parity of the number of sites. Integer spin chains
are treated in terms of the non-linear sigma model, while half-odd integer spin
chains are discussed in a renormalization group approach leading to a Luttinger
liquid with Aharonov-Bohm type boundary conditions.Comment: 12 pages, LaTe
Frustrated antiferromagnetic quantum spin chains for spin length S > 1
We investigate frustrated antiferromagnetic Heisenberg quantum spin chains at
T=0 for S=3/2 and S=2 using the DMRG method. We localize disorder and Lifshitz
points, confirming that quantum disorder points can be seen as quantum remnants
of classical phase transitions. Both in the S=3/2 and the S=2 chain, we observe
the disappearance of effectively free S=1/2 and S=1 end spins respectively. The
frustrated spin chain is therefore a suitable system for clearly showing the
existence of free end spins S'=[S/2] also in half-integer antiferromagnetic
spin chains with S>1/2. We suggest that the first order transition found for
S=1 in our previous work is present in all frustrated spin chains with S>1/2,
characterized by the disappearance of effectively free end spins with S'=[S/2].Comment: 6 pages, 8 ps figures, uses RevTeX, submitted to PR
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