Phase transitions in the binary-alloy Hubbard model: Insights from strong-coupling perturbation theory

Abstract

In the binary-alloy with composition AxB1−x of two atoms with ionic energy scales ±∆, an apparent Anderson insulator (AI) is obtained as a result of randomness in the position of atoms. Using our recently developed technique that combines the local self-energy from strong-coupling perturbation theory with the transfer matrix method, we are able to address the problem of adding a Hubbard U to the binary alloy problem for millions of lattice sites on the honeycomb lattice. By adding the Hubbard interaction U , the resulting AI phase will become metallic which in our formulation can be clearly attributed to the screening of disorder by Hubbard U . Upon further increase in U , again the AI phase emerges which can be understood in terms of the suppressed charge fluctuations due to residual Hubbard interaction of which the randomness takes advantage and localizes the quasi-particles of the metallic phase. The ultimate destiny of the system at very large U is to become a Mott insulator (MI). We construct the phase diagram of this model in the plane of (U, ∆) for various compositions x.

Optical conductivity of triple point fermions

“…Other interesting physical phenomena associated with triple point fermions include topological Lifshitz transitions [10] and anomalies in transport [22]. The effect of the electron-electron interactions and disorders in Dirac materials and flat bands have been studied in different papers [23][24][25][26][27][28]. Interactions can produce different phases like superconductivity, spin density wave, antiferromagnetic order, and other phases in such systems [29,30].…”

An intermediate phase induced by dilution in a correlated Dirac Fermi system

“…Interestingly, both types of disorder destroy the AFM order for dynamic properties [27]. Another example is using strong-coupling perturbation theory to study the Anderson Hubbard model on the honeycomb lattice, where an intermediate metallic state * txma@bnu.edu.cn is present between the Anderson insulator and Mott insulator under binary-alloy disorder but absent under uniformly distributed disorder [28,29].…”