2016/08/25 by Gabriel A. Canova, Yan Levin, Jeferson J. Arenzon · 1 citation
Physics and Astronomy · #cond-mat.stat-mech #cond-mat.soft
paper · pdf · doi:10.1103/physreve.94.032140
published as Phys. Rev. E 94, 032140 (2016) · 13 pages, 16 figures
arxiv created 2016/08/25 · arxiv updated 2016/10/05
We study a generalization of the XY model with an additional nematic-like term through extensive numerical simulations and finite-size techniques, both in two and three dimensions. While the original model favors local alignment, the extra term induces angles of 2π/q between neighboring spins. We focus here on the q=8 case (while presenting new results for other values of q as well) whose phase diagram is much richer than the well known q=2 case. In particular, the model presents not only continuous, standard transitions between Berezinskii-Kosterlitz-Thouless (BKT) phases as in q=2, but also infinite order transitions involving intermediate, competition driven phases absent for q=2 and 3. Besides presenting multiple transitions, our results show that having vortices decoupling at a transition is not a suficient condition for it to be of BKT type.