89,862 research outputs found
Chirality driven anomalous Hall effect in weak coupling regime
Anomalous Hall effect arising from non-trivial spin configuration (chirality)
is studied based on the - model. Considering a weak coupling case, the
interaction is treated perturbatively. Scattering by normal impurities is
included. Chirality is shown to drive locally Hall current and leads to overall
Hall effect if there is a finite uniform chirality. This contribution is
independent of the conventional spin-orbit contribution and shows distinct low
temperature behavior. In mesoscopic spin glasses, chirality-induced anomalous
Hall effect is expected below the spin-glass transition temperature.
Measurement of Hall coefficient would be useful in experimentally confirming
the chirality ordering
Controllable switching of vortex chirality in magnetic nanodisks by a field pulse
We propose a way of fast switching the chirality in a magnetic nanodisk by
applying a field pulse. To break the symmetry with respect to clockwise or
counterclockwise chirality a mask is added by which an inhomogeneous field
influences the vortex state of a nanodisk. Using numerical spin--lattice
simulations we demonstrate that chirality can be controllably switched by a
field pulse, whose intensity is above some critical value. A mathematical
definition for the chirality of an arbitrary shaped particle is proposed.Comment: REVTeX, 4 pages, 3 figure
Probing and controlling spin chirality in Mott insulators by circularly polarized laser
Scalar spin chirality, a three-body spin correlation that breaks
time-reversal symmetry, is revealed to couple directly to circularly polarized
laser. This is shown by the Floquet formalism for the periodically driven
repulsive Hubbard model with a strong-coupling expansion. A systematic
derivation of the effective low-energy Hamiltonian for a spin degree of freedom
reveals that the coupling constant for scalar spin chirality can become
significant for a situation in which the driving frequency and the on-site
interaction are comparable. This implies that the scalar chirality can be
induced by circularly polarized lights, or that it can be used conversely for
probing the chirality in Mott insulators as a circular dichroism.Comment: 10 pages, 8 figure
Chirality blockade of Andreev reflection in a magnetic Weyl semimetal
A Weyl semimetal with broken time-reversal symmetry has a minimum of two
species of Weyl fermions, distinguished by their opposite chirality, in a pair
of Weyl cones at opposite momenta that are displaced in the direction
of the magnetization. Andreev reflection at the interface between a Weyl
semimetal in the normal state (N) and a superconductor (S) that pairs
must involve a switch of chirality, otherwise it is blocked. We show that this
"chirality blockade" suppresses the superconducting proximity effect when the
magnetization lies in the plane of the NS interface. A Zeeman field at the
interface can provide the necessary chirality switch and activate Andreev
reflection.Comment: 15 pages, 9 figures. V2: added investigation of the dependence of the
chirality blockade on the direction of the magnetization and (Appendix C)
calculations of the Fermi-arc mediated Josephson effec
Monte Carlo studies of the ordering of the one-dimensional Heisenberg spin glass with long-range power-law interactions
The nature of the ordering of the one-dimensional Heisenberg spin-glass model
with a long-range power-law interaction is studied by extensive Monte Carlo
simulations, with particular attention to the issue of the spin-chirality
decoupling/coupling. Large system sizes up to are studied. With
varying the exponent describing the power-law interaction, we observe
three distinct types of ordering regimes. For smaller , the spin and
the chirality order at a common finite temperature with a common
correlation-length exponent, exhibiting the standard spin-chirality coupling
behavior. For intermediate , the chirality orders at a temperature
higher than the spin, exhibiting the spin-chirality decoupling behavior. For
larger , both the spin and the chirality order at zero temperature. We
construct a phase diagram in the versus the temperature plane, and
discuss implications of the results. Critical properties associated with both
the chiral-glass and the spin-glass transitions are also determined.Comment: 28 pages, 26 figures, to appear in J. Phys. Soc. Jp
Dynamical Local Chirality and Chiral Symmetry Breaking
We present some of the reasoning and results substantiating the notion that
spontaneous chiral symmetry breaking (SChSB) in QCD is encoded in local chiral
properties of Dirac eigenmodes. Such association is possible when viewing
chirality as a dynamical effect, measured with respect to the benchmark of
statistically independent left-right components. Following this rationale leads
to describing local chiral behavior by a taylor-made correlation, namely the
recently introduced correlation coefficient of polarization C_A. In this
language, correlated modes (C_A>0) show dynamical preference for local
chirality while anti-correlated modes (C_A<0) favor anti-chirality. Our
conclusion is that SChSB in QCD can be viewed as dominance of low-energy
correlation (chirality) over anti-correlation (anti-chirality) of Dirac sea.
The spectral range of local chirality, chiral polarization scale Lambda_ch, is
a dynamically generated scale in the theory associated with SChSB. One
implication of these findings is briefly discussed.Comment: 8 pages, 4 figures. Talk given at "Quark Confinement and the Hadron
Spectrum X", Munich, Germany, Oct. 8-12, 201
On the Microscopic Origin of Cholesteric Pitch
We present a microscopic analysis of the instability of the nematic phase to
chirality when molecular chirality is introduced perturbatively. We show that
previously neglected short-range biaxial correlations play a crucial role in
determining the cholesteric pitch. We propose an order parameter which
quantifies the chirality of a molecule.Comment: RevTeX 3.0, 4 pages, one included eps figure. Published versio
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