2 research outputs found
Interplay of anisotropy and frustration: triple transitions in a triangular-lattice antiferromagnet
The classical Heisenberg antiferromagnet on a triangular lattice with the
single-ion anisotropy of the easy-axis type is theoretically investigated. The
mean-field phase diagram in an external magnetic field is constructed. Three
finite-temperature Berezinskii-Kosterlitz-Thouless transitions are found by the
Monte Carlo simulations in zero field. The two upper transitions are related to
the breaking of the discrete symmetry group, while the lowest
transition is associated with a quasi-long-range ordering of transverse
components. The intermediate collinear phase between first and second
transitions is the sliding phase predicted by J. V. Jos\'e {\it et al}. [Phys.
Rev. B {\bf 16}, 1217 (1977)].Comment: 7 pages, 10 figures, section 2 profoundly changed, other minor
amendments, references updated; version for publicatio
Nonequilibrium relaxation study of the anisotropic antiferromagnetic Heisenberg model on the triangular lattice
Effect of exchange anisotropy on the relaxation time of spin and vector
chirality is studied for the antiferromagnetic classical Heisenberg model on
the triangular lattice by using the nonequilibrium relaxation Monte Carlo
method. We identify the Berezinskii-Kosterlitz-Thouless (BKT) transition and
the chiral transition in a wide range of the anisotropy, even for very small
anisotropy of 0.01%. As the anisotropy decreases, both the critical
temperatures steeply decrease, while the BKT critical region becomes
divergently wide. We elucidate a sharp "V shape" of the phase diagram around
the isotropic Heisenberg point, which suggests that the isotropic case is
exceptionally singular and the associated Z vortex transition will be isolated
from the BKT and chiral transitions. We discuss the relevance of our results to
peculiar behavior of the spin relaxation time observed experimentally in
triangular antiferromagnets.Comment: 5 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp