NONUNIVERSAL CRITICAL-BEHAVIOR AND 1ST-ORDER TRANSITIONS IN A COUPLED XY-ISING MODEL

Article

关键词: SPACE RENORMALIZATION-GROUP;    PHASE-TRANSITIONS;    MONTE-CARLO;    TRIANGULAR LATTICE;    COULOMB-GAS;    JUNCTION ARRAYS;    MAGNETIC-FIELD;    CRITICAL-POINT;    CENTRAL CHARGE;    COMPLEX ZEROS;   

DOI  :  10.1103/PhysRevB.44.4819

来源: SCIE

【 摘 要 】

We study, by a Migdal-Kadanoff approximation and Monte Carlo simulations, the phase diagram of a two-dimensional coupled XY-Ising model. This model can describe phase transitions in different systems with underlying continuous and Z2 symmetries. Depending on the parameters, we find separate XY, Ising and first-order transitions. Also, a line of continuous transitions is found with simultaneous loss of XY and Ising order and varying critical exponents. The fully frustrated XY and Josephson-junction systems can be considered to lie along different paths in the model which can result in nonuniversal behavior if the transition is a single one.

【 授权许可】

Free