Interacting fermions in two dimension in simultaneous presence of disorder and magnetic field

TL;DR

This study investigates how disorder and electronic interactions influence the Hofstadter butterfly pattern in two-dimensional lattices, revealing lattice-dependent effects on entanglement and spectral properties.

Contribution

It demonstrates the differential impact of disorder and interactions on the Hofstadter butterfly revival and entanglement characteristics in square and honeycomb lattices.

Findings

Revival of Hofstadter butterfly is more prominent in square lattices.

Disorder and interaction affect entanglement entropy and spectrum differently in the two lattices.

Symmetry of entanglement spectrum is preserved in honeycomb but not in square lattice.

Abstract

We have studied the revival of Hofstadter butterfly due to the competition between disorder and electronic interaction using mean field approximation of unrestricted Hartree Fock method at zero temperature for two dimensional square and honeycomb lattices. Interplay of disorder and electronic correlation to nullify each other is corroborated by the fact that honeycomb lattice needs more strength of electronic correlation owing to its less co-ordination number which enhances the effect of disorder. The extent of revival of the butterfly is better in square than honeycomb lattice due to higher coordination number. The effect of disorder and interaction is also investigated to study entanglement entropy and entanglement spectrum. It has been observed that for the square lattice, area law of entanglement entropy is violated for intermediate strength magnetic and magnitude of such departure from area law depends on disorder and interaction as well. However such departure from area law is absence for honeycomb lattice. Moreover the entanglement spectrum for square lattice does have the symmetry of original Hofstadter butterfly and this symmetry is destroyed in the presence of disorder. The interaction opens up a gap in the entanglement spectrum as well. For the honeycomb lattice, the entanglement spectrum forms a continuous band without any symmetry and its feature is mostly unchanged in the presence of disorder as well as interaction.