Disorder effect induced by electron-electron interaction

Zvi Ovadyahu

Sufficiently strong disorder localizes the wave functions of a degenerate Fermi gas. The Coulomb interaction in such a medium renders the system a glass, exhibiting slow relaxation and a rich variety of memory effects. These establish the electron glass as a versatile system for the study of the interplay between disorder and interaction. Here, the author reports on a reversible charge-ordering process in an amorphous electron glass. This occurs while the disorder is considerably stronger than the interaction, which may suggest the relevance of quantum coherent effects.

Raúl Oviedo‐Roa, C. Wang, Oracio Navarro

Heiner Linke, P. Omling, H. Xu +1 more

Saptarshi Mandal, Sanjay Gupta

We study 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 lattice than honeycomb lattice due to higher coordination number. The effect of disorder and interaction is also investigated to study entanglement entropy and entanglement spectrum. We find that for honeycomb lattice area law of entanglement entropy is obeyed in all cases but for square lattice there is some departure from area law for larger subsystems. The entanglement spectrum have the reflection symmetry of the original butterfly of the Hofstadter spectrum. The interaction induces a gap in the entanglement spectrum as well conforming the correspondence between physical spectrum and entanglement spectrum. The effect of disorder closes the interaction induced gap in the entanglement spectrum establishing the nullification of interaction due to disorder and vice versa.

S. V. Kravchenko

Chinedu E. Ekuma

We study the combined impact of random disorder and electron-electron and electron-hole interactions on the absorption spectra of a three-dimensional Hubbard Hamiltonian. We determine the single-particle Green's function within the typical medium dynamical cluster approximation. We solve the Bethe-Salpeter equation (BSE) to obtain the dynamical conductivity. Our results show that increasing disorder strength at a given interaction strength leads to decreased absorption with the dynamical conductivity, systematically going to zero at all frequencies, a fingerprint of a correlation-mediated electron localization. Surprisingly, our data reveal that taking into account the effects of electron-hole interactions through the BSE significantly changes the oscillator strength with a concomitant reduction in the critical disorder strengths ${W}_{c}^{U}$. We attribute this behavior to enhanced quantum correction induced by electron-hole interactions.