New chirality transition of classical Heisenberg model with easy-plane anisotropy on a two-layer triangular lattice

We investigate a classical Heisenberg model with easy-plane anisotropy on a two-layer triangular lattice by using Monte Carlo simulations. The internal energy, the specific heat, the chirality and the Binder parameter are calculated in order to clarify phase transitions and critical phenomena. In some range of interaction parameters, we find that the chirality shows a very steep increase as temperature increases in a temperature range; the value of a critical exponent for this change is estimated.