Spin-dynamics simulations of the triangular antiferromagnetic XY model

Article

关键词: CLASSICAL HEISENBERG-ANTIFERROMAGNET;    EASY-PLANE FERROMAGNETS;    MONTE-CARLO SIMULATION;    2 DIMENSIONS;    PHASE-TRANSITIONS;    CRITICAL-BEHAVIOR;    LATTICE;    SYSTEMS;    ALGORITHMS;    ANISOTROPY;   

DOI  :  10.1103/PhysRevB.66.174403

来源: SCIE

【 摘 要 】

Using Monte Carlo and spin-dynamics methods, we have investigated the dynamic behavior of the classical, antiferromagnetic XY model on a triangular lattice with linear sizes L greater-than-or-equal-to 300. The temporal evolutions of spin configurations were obtained by solving numerically the coupled equations of motion for each spin using fourth-order Suzuki-Trotter decompositions of exponential operators. From space- and time-displaced spin-spin correlation functions and their space-time Fourier transforms we obtained the dynamic structure factor S(q,w) for momentum q and frequency omega. Below TKT (Kosterlitz-Thouless transition), both the in-plane (Sxx) and out-of-plane (Szz) components of S(q,omega) exhibit very strong and sharp spin-wave peaks. Well above TKT, Sxx and Szz apparently display a central peak, and spin-wave signatures are still seen in Szz. In addition, we also observed an almost dispersionless domain-wall peak at high omega below Tc (Ising transition), where long-range order appears in the staggered chirality. Above Tc, the domain-wall peak disappears for all q. The line shape of these peaks is captured reasonably well by a Lorentzian form. Using a dynamic finite-size scaling theory, we determined the dynamic critical exponent z=1.002(3). We found that our results demonstrate the consistency of the dynamic finite-size scaling theory for the characteristic frequency omega-m and the dynamic structure factor S(q,omega) itself.

【 授权许可】

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