1,798 research outputs found
A two-channel Kondo impurity in the spin-1/2 chain: Consequences for Knight shift experiments
A magnetic impurity in the spin-1/2 chain is a simple realization of the
two-channel Kondo problem since the field theoretical descriptions in the
spin-sector are identical. The correlation functions near the impurity can be
calculated. Using a modified version of the numerical transfer matrix DMRG, we
are able to accurately determine local properties close to the impurity in the
thermodynamic limit. The local susceptibilities (Knight-shifts) show an
interesting behavior in a large range around the impurities. We are able to
make quantitative experimental predictions which would allow to observe
two-channel Kondo physics for the first time directly by doping of spin-1/2
chain compounds.Comment: 2 pages in revtex format including 2 embedded figures (using epsf
Quantum Phase Transition in a Resonant Level Coupled to Interacting Leads
An interacting one-dimensional electron system, the Luttinger liquid, is
distinct from the "conventional" Fermi liquids formed by interacting electrons
in two and three dimensions. Some of its most spectacular properties are
revealed in the process of electron tunneling: as a function of the applied
bias or temperature the tunneling current demonstrates a non-trivial power-law
suppression. Here, we create a system which emulates tunneling in a Luttinger
liquid, by controlling the interaction of the tunneling electron with its
environment. We further replace a single tunneling barrier with a
double-barrier resonant level structure and investigate resonant tunneling
between Luttinger liquids. For the first time, we observe perfect transparency
of the resonant level embedded in the interacting environment, while the width
of the resonance tends to zero. We argue that this unique behavior results from
many-body physics of interacting electrons and signals the presence of a
quantum phase transition (QPT). In our samples many parameters, including the
interaction strength, can be precisely controlled; thus, we have created an
attractive model system for studying quantum critical phenomena in general. Our
work therefore has broadly reaching implications for understanding QPTs in more
complex systems, such as cold atoms and strongly correlated bulk materials.Comment: 11 pages total (main text + supplementary
A Kondo impurity in one dimensional correlated conduction electrons
A spin-1/2 magnetic impurity coupled to a one-dimensional correlated electron
system have been studied by applying the density renormalization group method.
The Kondo temperature is substantially enhanced by strong repulsive
interactions in the chain, but changes non-monotonically in the case of
electron attraction. The magnetization of the impurity at zero- temperature
shows local Fermi liquid behavior.Comment: 4 pages and 4 figures; ps-file
Spectral properties of one dimensional insulators and superconductors
Conformal field theory and Bethe ansatz are used to investigate the low
energy features of the spectral function in one dimensional models which
exhibit a gap in the spin or in the charge excitation spectrum. Exotic behavior
is found in the superconducting case, where the Green function displays
momentum dependent Luttinger Liquid exponents. The predictions of the formalism
are confirmed by Lanczos diagonalizations in the model up to 32 sites.
These results may be relevant in connection to photoemission experiments in
quasi one dimensional insulators or superconductors.Comment: 11 pages , RevTeX , 3 uuencoded picture
The continuum limit of the integrable open XYZ spin-1/2 chain
We show that the continuum limit of the integrable XYZ spin-1/2 chain on a
half-line gives rise to the boundary sine-Gordon theory using the perturbation
method.Comment: 8pages, LaTeX; typos in eq.(11) removed, one in reference correcte
Non-Hermitian Luttinger Liquids and Vortex Physics
As a model of two thermally excited flux liquids connected by a weak link, we
study the effect of a single line defect on vortex filaments oriented parallel
to the surface of a thin planar superconductor. When the applied field is
tilted relative to the line defect, the physics is described by a nonhermitian
Luttinger liquid of interacting quantum bosons in one spatial dimension with a
point defect. We analyze this problem using a combination of analytic and
numerical density matrix renormalization group methods, uncovering a delicate
interplay between enhancement of pinning due to Luttinger liquid effects and
depinning due to the tilted magnetic field. Interactions dramatically improve
the ability of a single columnar pin to suppress vortex tilt when the Luttinger
liquid parameter g is less than or equal to one.Comment: 4 pages, 5 eps figures, minor changes made, one reference adde
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