Reentrant Phase Diagram of Two-Dimensional Electron Gas

TL;DR

This paper investigates the phase diagram of a two-dimensional electron gas on a square lattice under a magnetic field, revealing reentrant phases and new fixed points through a renormalization approach.

Contribution

It introduces a novel renormalization scheme to analyze how next-nearest neighbor couplings affect phase transitions and universality classes in 2D electron systems.

Findings

Reentrant extended phase appears due to next-nearest neighbor coupling asymmetry.

Universal strange attractor is replaced by a new fixed point.

Reentrant phases belong to the anisotropic triangular lattice universality class.

Abstract

We study the phase diagram of an electron on a square lattice in a transverse magnetic field. Using a renormalization scheme, we show that the inequality of the two next-nearest neighbor couplings destroys the fat critical regime above the bicritical line and replaces it with another reentrant extended phase. Furthermore, the universal strange attractor describing self-similar fluctuations of the localized phase is replaced by a new fixed point. The reentrant extended phase and the new fixed point of the localized phase belong to the universality class of an anisotropic triangular lattice.