Ground state of antiferromagnetic thin films of the XY model under magnetic field and uniaxial potential

We investigate ground-state properties of antiferromagnetic thin films of the 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 number of layers. A number of phases appearing in a system with an even number of layers is larger than that in a system with an odd number of layers. We elucidate those by obtaining phase diagrams for the systems with 10 layers and 11 layers.