Critical properties of XY model on twolayer Villain ferromagnetic lattice
Abstract
We investigate phase transitions of the XY model on a twolayer square lattice which consists of a Villain plane (J) and a ferromagnetic plane (I), using Monte Carlo simulations and a histogram method. Depending on the values of interaction parameters (I,J), the system presents three phases: namely, a KosterlitzThouless (KT) phase in which the two planes are critical for I predominant over J, a chiral phase in which the two planes have a chiral order for J predominant over I and a new phase in which only the Villain plane has a chiral order and the ferromagnetic plane is paramagnetic with a small value of chirality. We clarify the nature of phase transitions by using a finite size scaling method. We find three different kinds of transitions according to the values of (I,J): the KT transition, the Ising transition and an XYIsing transition with nu = 0.849(3). It turns out that the Ising or XYIsing transition is associated with the disappearance of the chiral order in the Villain plane.
 Publication:

Chinese Physics
 Pub Date:
 February 2004
 DOI:
 10.1088/10091963/13/2/022
 Bibcode:
 2004ChPhy..13..251W
 Keywords:

 XY model;
 chirality;
 KT transition;
 twolayer Villain lattice