Probing vortex unbinding via dipole fluctuations

Article

关键词: 2-DIMENSIONAL XY-MODEL;    RENORMALIZATION;   

DOI  :  10.1103/PhysRevB.66.201402

来源: SCIE

【 摘 要 】

We develop a numerical method for detecting a vortex-unbinding transition in a two-dimensional system by measuring large-scale fluctuations in the total vortex dipole moment (P) over right arrow of the system. These are characterized by a quantity Fthat measures the number of configurations in a simulation for which either P-x or P-y is half the system size. It is shown that F tends to a nonvanishing constant for large system sizes in the unbound phase, and vanishes in the bound phase. The method is applied to the XY model both in the absence and in the presence of a magnetic field. In the latter case, the system size dependence of F suggests that there exist three distinct phases, one unbound vortex phase, a logarithmically bound phase, and a linearly bound phase.

【 授权许可】

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