1209.2520 (Ryo Tamura et al.)

Second-Order Phase Transition in Heisenberg Model on Triangular Lattice
with Competing Interactions    [PDF]

Ryo Tamura, Shu Tanaka, Naoki Kawashima

We study the nature of phase transition in classical Heisenberg model on triangular lattice with competing interactions. In frustrated systems, various types of phase transitions occur depending on the lattice and spin symmetries. Recently, a first-order phase transition with threefold symmetry breaking in frustrated Heisenberg model on triangular lattice was discovered [R. Tamura and N. Kawashima, J. Phys. Soc. Jpn. 80, 074008 (2011)]. To change the underlying symmetry, we introduce a uniaxial distortion effect into their model. We find the order of the phase transition changes into the second order when the spontaneous breaking of the twofold symmetry occurs. Moreover, dissociation of Z_2 vortex pairs occurs at the second-order phase transition point.

View original: http://arxiv.org/abs/1209.2520