Density wave and topological reconstruction of an isotropic two-dimensional electron band in external magnetic field

TL;DR

This paper predicts that a strong magnetic field can induce a uniaxial density wave in an isotropic two-dimensional electron system, causing a topological Fermi surface transformation and quantum oscillations, with a phase transition at zero temperature.

Contribution

It introduces a novel mechanism where magnetic fields induce density waves and Fermi surface reconstruction in isotropic 2D metals, highlighting a quantum phase transition.

Findings

Magnetic field induces a density wave and Fermi surface change.

Quantum oscillations similar to de Haas - van Alphen effect observed.

Critical coupling decreases with increasing magnetic field.

Abstract

We predict a mechanism of spontaneous stabilization of a uniaxial density wave in a two-dimensional metal with an isotropic Fermi surface in the presence of external magnetic field. The topological transformation of a closed Fermi surface into an open one decreases the electron band energy due to delocalization of electrons initially localized by magnetic field, additionally affected by the magnetic breakdown effect. The driving mechanism of such reconstruction is a periodic potential due to the self-consistently formed electron density wave. It is accompanied with quantum oscillations periodic in inverse magnetic field, similar to the standard de Haas - van Alphen effect, due to Landau level filling. The phase transition appears as a quantum one at T=0, provided the relevant coupling constant is above the critical one. This critical value rapidly decreases, and finally saturates toward zero on the scale of tens of Tesla. Thus, a strong enough magnetic field can induce the density wave in the system in which it was absent in zero field.