Finite temperature semimetal-insulator transition on the honeycomb lattice

TL;DR

This paper investigates the finite temperature phase transition from semimetal to insulator in the Hubbard model on the honeycomb lattice using dynamical mean field theory, revealing a complex transition structure with first and second order features.

Contribution

It provides the first detailed analysis of the finite temperature phase diagram and transition nature in the honeycomb lattice Hubbard model using DMFT.

Findings

Identifies a first-order transition line ending in a second-order point.

Discovers phase separation between semimetal and insulator at low temperatures.

Constructs the phase diagram showing crossover and transition lines.

Abstract

A semimetal-insulator transition in the Hubbard model on the honeycomb lattice is studied by using the dynamical mean field theory. Electrons in the honeycomb lattice resemble the Dirac electron liquid and for weak interactions the system is semimetal. With increasing the local interaction a semimetal-insulator transition occurs. We find a nonanalytical structure of the phase transition which consists of a first-order transition line ending in a second-order transition point and high-temperature crossover line. A phase separation of semimetal and insulator occurs at low temperatures. Maxwell construction is performed to determine the first order transition line. The phase diagram is also presented.