We investigate phase transitions of the XY model on a two-layer triangular lattice when interactions are competing, by using Monte Carlo simulations. For the system with a ferromagnetic interaction on one of two layers and an antiferromagnetic interaction on the other layer, we find two...

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...

We investigate ground-state properties of antiferromagnetic thin films of the XY model under an external magnetic field and a uniaxial potential by numerical calculations. We clarify surface effects by comparing the ground-state properties of thin films with those of the system with infinite...