Chiral phase transition in a planar four-Fermi model in a tilted magnetic field

TL;DR

This paper investigates how tilted magnetic fields influence chiral symmetry breaking in a planar four-Fermi model, revealing complex phase diagrams with multiple critical points and potential experimental implications in condensed matter systems.

Contribution

It introduces a detailed analysis of the combined effects of parallel and perpendicular magnetic field components on chiral phase transitions in a planar fermionic model.

Findings

Perpendicular magnetic field enhances chiral symmetry breaking.

Parallel magnetic field weakens chiral symmetry via Zeeman energy.

Complex phase diagrams with multiple critical points and reentrant transitions emerge.

Abstract

We study a planar four-Fermi Gross-Neveu model in the presence of a tilted magnetic field, with components parallel and perpendicular to the system's plane. We determine how this combination of magnetic field components, when applied simultaneously, affects the phase diagram of the model. It is shown that each component of the magnetic field causes a competing effect on the chiral symmetry in these fermionic systems. While the perpendicular component of the magnetic field tends to make the chiral symmetry breaking stronger, the effect of the parallel component of the field in these planar systems is to weaken the chiral symmetry through the enhancement of the Zeeman energy term. We show that this competing effect, when combined also with temperature and chemical potential, can lead to a rich phase diagram, with the emergence of multiple critical points and reentrant phase transitions. We also study how the presence of these multiple critical points and reentrant phases can manifest in the quantum Hall effect. Our results provide a possible way to probe experimentally chiral symmetry breaking and the corresponding emergence of a gap (i.e., the presence of a nonvanishing chiral vacuum expectation value) in planar condensed matter systems of current interest.