4,995 research outputs found
Vector chiral states in low-dimensional quantum spin systems
A class of exact spin ground states with nonzero averages of vector spin
chirality, , is presented. It is
obtained by applying non-uniform O(2) rotations of spin operators in the XY
plane on the SU(2)-invariant Affleck-Kennedy-Lieb-Tasaki (AKLT) states and
their parent Hamiltonians. Excitation energies of the new ground states are
studied with the use of single-mode approximation in one dimension for S=1. The
excitation gap remains robust. Construction of chiral AKLT states is shown to
be possible in higher dimensions. We also present a general idea to produce
vector chirality-condensed ground states as non-uniform O(2) rotations of the
non-chiral parent states. Dzyaloshinskii-Moriya interaction is shown to imply
non-zero spin chirality.Comment: 4 pages, 1 figur
Coupling of phonons and spin waves in triangular antiferromagnet
We investigate the influence of the spin-phonon coupling in the triangular
antiferromagnet where the coupling is of the exchange-striction type. The
magnon dispersion is shown to be modified significantly at wave vector (2pi,0)
and its symmetry-related points, exhibiting a roton-like minimum and an
eventual instability in the dispersion. Various correlation functions such as
equal-time phonon correlation, spin-spin correlation, and local magnetization
are calculated in the presence of the coupling.Comment: 6 pages, 5 figures; references added, minor text revisions, submitted
to PR
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