Nonequilibrium relaxation study of the anisotropic antiferromagnetic Heisenberg model on the triangular lattice

Abstract

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 $\sim$ 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.

arXiv comment5 pages, 4 figures, accepted for publication in J. Phys. Soc. Jpn

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Cited by in corpus (4)

• Phase diagram of the classical Heisenberg antiferromagnet on a triangular lattice in applied magnetic field
• First-Order Phase Transition with Breaking of Lattice Rotation Symmetry in Continuous-Spin Model on Triangular Lattice
• Softened magnetic excitations in the s = 3/2 distorted triangular antiferromagnet alpha-CaCr2O4
• Monte Carlo study on low-temperature phase diagrams of the $J_1$-$J_2$ classical $XY$ kagome antiferromagnet