5,495 research outputs found
Solutions to the Multi-Component 1/R Hubbard Model
In this work we introduce one dimensional multi-component Hubbard model of
1/r hopping and U on-site energy. The wavefunctions, the spectrum and the
thermodynamics are studied for this model in the strong interaction limit
. In this limit, the system is a special example of Luttinger
liquids, exhibiting spin-charge separation in the full Hilbert space.
Speculations on the physical properties of the model at finite on-site energy
are also discussed.Comment: 9 pages, revtex, Princeton-May1
Majorana bound state in rotating superfluid 3He-A between parallel plates
A concrete and experimentally feasible example for testing the putative
Majorana zero energy state bound in a vortex is theoretically proposed for a
parallel plate geometry of superfluid He-A phase. We examine the
experimental setup in connection with ongoing rotating cryostat experiments.
The theoretical analysis is based on the well-established Ginzburg--Landau
functional, supplemented by microscopic calculations of the Bogoliubov--de
Gennes equation, both of which allow the precise location of the parameter
regions of the Majorana state to be found in realistic situations.Comment: 5 pages, 4 figure
On Models with Inverse-Square Exchange
A one-dimensional quantum N-body system of either fermions or bosons with
colors interacting via inverse-square exchange is presented in this
article. A class of eigenstates of both the continuum and lattice version of
the model Hamiltonians is constructed in terms of the Jastrow-product type wave
function. The class of states we construct in this paper corresponds to the
ground state and the low energy excitations of the model that can be described
by the effective harmonic fluid Hamiltonian. By expanding the energy about the
ground state we find the harmonic fluid parameters (i.e. the charge, spin
velocities, etc.), explicitly. The correlation exponent and the compressibility
of are also found. As expected the general harmonic relation(i.e.
) is satisfied among the charge and spin velocities.Comment: 26 page
Stability of half quantum vortex in rotating superfluid 3He-A between parallel plates
We have found the precise stability region of the half quantum vortex (HQV)
for superfluid He A phase confined in parallel plates with a narrow gap
under rotation. Standard Ginzburg-Landau free energy, which is well
established, is solved to locate the stability region spanned by temperature
and rotation speed (). This - stability region is wide
enough to check it experimentally in available experimental setup. The detailed
order parameter structure of HQV characterized by A core is given to
facilitate the physical reasons of its stability over other vortices or
textures.Comment: 5 pages, 4 figure
Entropy and Barrier-Hopping Determine Conformational Viscoelasticity in Single Biomolecules
Biological macromolecules have complex and non-trivial energy landscapes,
endowing them a unique conformational adaptability and diversity in function.
Hence, understanding the processes of elasticity and dissipation at the
nanoscale is important to molecular biology and also emerging fields such as
nanotechnology. Here we analyse single molecule fluctuations in an atomic force
microscope (AFM) experiment using a generic model of biopolymer viscoelasticity
that importantly includes sources of local `internal' conformational
dissipation. Comparing two biopolymers, dextran and cellulose, polysaccharides
with and without the well-known `chair-to-boat' transition, reveals a signature
of this simple conformational change as minima in both the elasticity and
internal friction around a characteristic force. A calculation of two-state
populations dynamics offers a simple explanation in terms of an elasticity
driven by the entropy, and friction by barrier-controlled hopping, of
populations on a landscape. The microscopic model, allows quantitative mapping
of features of the energy landscape, revealing unexpectedly slow dynamics,
suggestive of an underlying roughness to the free energy.Comment: 25 pages, 7 figures, naturemag.bst, modified nature.cls
(naturemodified.cls
Exact results for SU(3) spin chains: trimer states, valence bond solids, and their parent Hamiltonians
We introduce several exact models for SU(3) spin chains: (1) a
translationally invariant parent Hamiltonian involving four-site interactions
for the trimer chain, with a three-fold degenerate ground state. We provide
numerical evidence that the elementary excitations of this model transform
under representation 3bar of SU(3) if the original spins of the model transform
under rep. 3. (2) a family of parent Hamiltonians for valence bond solids of
SU(3) chains with spin reps. 6, 10, and 8 on each lattice site. We argue that
of these three models, only the latter two exhibit spinon confinement and a
Haldane gap in the excitation spectrum
Hepatitis C and the Social Hierarchy: How Stigma Is Built in Rural Communities
Although Hepatitis C has profound impacts on individuals living in communities, most research has been conducted in a hospital or laboratory setting. Additionally, there is a lack of research exploring the social effects of Hepatitis C in rural communities. In this qualitative study, we focus on perceptions on Hepatitis C within a rural community, describe how the local residents perceive social hierarchy within their community, and explore the process of stigma building. Informed by a grounded theory approach, we employed a snowball sampling strategy in a southern rural area to conduct in-depth, open-ended interviews. In our findings we describe how local restaurants were often utilized as places to exchange personal opinions on various community issues among the upper hierarchical members, consider the ways social hierarchy influences peopleās perceptions, and explore community membersā response to the problem of ignored viral infections within the community. We found the community leaders are earning the trust by living in the community for an extended period of time; therefore, they tend to be elderly yet remain active as members of various committees. Additionally, we argue that the common view of āfamily-like supportā in rural communities is largely a myth; it is a romanticized view of the rural living held and perpetuated by the upper-class people in the community. Therefore, instead of depending on idealized or imaginary social support, rural communities need to consider organizing a system of formal support
Magnetic Moment Formation in Graphene Detected by Scattering of Pure Spin Currents
Hydrogen adatoms are shown to generate magnetic moments inside single layer
graphene. Spin transport measurements on graphene spin valves exhibit a dip in
the non-local spin signal as a function of applied magnetic field, which is due
to scattering (relaxation) of pure spin currents by exchange coupling to the
magnetic moments. Furthermore, Hanle spin precession measurements indicate the
presence of an exchange field generated by the magnetic moments. The entire
experiment including spin transport is performed in an ultrahigh vacuum
chamber, and the characteristic signatures of magnetic moment formation appear
only after hydrogen adatoms are introduced. Lattice vacancies also demonstrate
similar behavior indicating that the magnetic moment formation originates from
pz-orbital defects.Comment: accepted to Phys. Rev. Let
Renormalized Harmonic-Oscillator Description of Confined Electron Systems with Inverse-Square Interaction
An integrable model for SU() electrons with inverse-square interaction
is studied for the system with confining harmonic potential. We develop a new
description of the spectrum based on the {\it renormalized
harmonic-oscillators} which incorporate interaction effects via the repulsion
of energy levels. This approach enables a systematic treatment of the
excitation spectrum as well as the ground-state quantities.Comment: RevTex, 7 page
Oscillatory Spin Polarization and Magneto-Optic Kerr Effect in Fe3O4 Thin Films on GaAs(001)
The spin dependent properties of epitaxial Fe3O4 thin films on GaAs(001) are
studied by the ferromagnetic proximity polarization (FPP) effect and
magneto-optic Kerr effect (MOKE). Both FPP and MOKE show oscillations with
respect to Fe3O4 film thickness, and the oscillations are large enough to
induce repeated sign reversals. We attribute the oscillatory behavior to
spin-polarized quantum well states forming in the Fe3O4 film. Quantum
confinement of the t2g states near the Fermi level provides an explanation for
the similar thickness dependences of the FPP and MOKE oscillations.Comment: to appear in Phys. Rev. Let
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