Thermal critical points from competing singlet formations in fully frustrated bilayer antiferromagnets

Abstract

We examine the ground-state phase diagram and thermal phase transitions in a plaquettized fully frustrated bilayer spin-1/2 Heisenberg model. Based on a combined analysis from sign-problem free quantum Monte Carlo simulations, perturbation theory and free-energy arguments, we identify a first-order quantum phase transition line that separates two competing quantum-disordered ground states with dominant singlet formations on inter-layer dimers and plaquettes, respectively. At finite temperatures, this line extends to form a wall of first-order thermal transitions, which terminates in a line of thermal critical points. From a perturbative approach in terms of an effective Ising model description, we identify a quadratic suppression of the critical temperature scale in the strongly plaquettized region. Based on free-energy arguments we furthermore obtain the full phase boundary of the low-temperature dimer-singlet regime, which agrees well with the quantum Monte Carlo data.

7 pages, 6 figures

References in corpus (3)

• Generalized Directed Loop Method for Quantum Monte Carlo Simulations
• Bridging lattice-scale physics and continuum field theory with quantum Monte Carlo simulations
• Quantum Monte Carlo simulations in the trimer basis: first-order transitions and thermal critical points in frustrated trilayer magnets

Cited by in corpus (4)

• Thermal first-order phase transitions, Ising critical points, and reentrance in the Ising-Heisenberg model on the diamond-decorated square lattice in a magnetic field
• Emergent criticality in fully frustrated quantum magnets
• Liquid-gas analog multicriticality in a frustrated Ising bilayer
• Carlo.jl: A general framework for Monte Carlo simulations in Julia