Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Correlated Electrons: Quantum-Critical Phenomena - Theory
TT 35.1: Vortrag
Dienstag, 8. März 2016, 14:00–14:15, H21
Thermal phase transitions in the vicinity of the quantum critical point of spinless fermions on the honeycomb lattice — •Stephan Hesselmann and Stefan Wessel — Institute for Theoretical Solid State Physics, JARA-FIT, and JARA-HPC, RWTH Aachen University, 52056 Aachen, Germany
We consider spinless fermions on a honeycomb lattice (spinless t−V model), which provide a minimal realization of lattice Dirac fermions. Nearest neighbor interactions drive a quantum phase transition from a semi-metallic phase to a charge ordered phase, which spontaneously breaks the chiral Z2 symmetry of the Dirac fermions. The critical theory is given by the Gross-Neveu-Yukawa theory, which describes the process of mass generation due to the broken chiral symmetry. At finite temperature (and V>Vc) the quantum critical point connects to a line of second order thermal phase transitions that restore the broken chiral symmetry. We employ a recent sign-problem-free continuous time quantum Monte Carlo method [1, 2] to investigate the finite temperature phase diagram of the model. Furthermore we give estimates for the critical exponents of the Gross-Neveu chiral Ising universality class by studying the extension of the quantum critical regime to finite temperatures.
[1] E. F. Huffman et al., PRB 89, 111101(R) (2014)
[2] L. Wang et al., New J. Phys. 16, 103008 (2014)