Dresden 2026 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 60: Critical Phenomena and Phase Transitions
DY 60.2: Vortrag
Freitag, 13. März 2026, 09:45–10:00, ZEU/0114
The frustrated Ising model on the honeycomb lattice: Metastability and universality — •Denis Gessert1,2,3, Martin Weigel3, and Wolfhard Janke2 — 1Centre for Fluid and Complex Systems, Coventry University, Coventry, CV1 5FB, United Kingdom — 2nstitut für Theoretische Physik, Universität Leipzig, IPF 231101, 04081 Leipzig, Germany — 3nstitut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
We study the Ising model with competing ferromagnetic nearest- and antiferromagnetic next-nearest-neighbor interactions of strengths J1 > 0 and J2 < 0, respectively, on the honeycomb lattice. For J2 > − J1 / 4 it has a ferromagnetic ground state, and previous work has shown that at least for J2 −0.2 J1 the transition is in the Ising universality class. For even lower J2 some indicators pointing towards a first-order transition were reported. By utilizing population annealing Monte Carlo simulations together with a rejection-free and adaptive update, we can equilibrate systems with J2 as low as −0.23 J1. By means of a finite-size scaling analysis we show that the system undergoes a second-order phase transition within the Ising universality class at least down to J2 =−0.23 J1 and, most likely, for all J2 > − J1 / 4. As we show here, there exist very long-lived metastable states in this system explaining the first-order like behavior seen in only partially equilibrated systems.
Keywords: Ising model; Frustration; Universality; Monte Carlo