Chirality transition of XY model on three-layer triangular lattice

We investigate phase transitions of XY model on a three-layer triangular lattice by assuming that the intralayer interactions on the first and the third layer are antiferromagnetic and the one on the second layer ferromagnetic. We use Monte Carlo simulations and find that there are two critical temperatures Tcl and Tcu (Tcl<Tcu) in some range of interaction constant on the second layer. We find that the chirality on the second layer shows a steep increase as temperature increases near and below the temperature Tcl and there is the usual chirality transition at Tcu. The specific heat shows different divergent behaviors at Tcl and at Tcu. The nature of critical phenomena is clarified by means of finite-size scaling analysis.