Finite-Temperature Charge Dynamics and the Melting of the Mott Insulator

TL;DR

This paper extends the slave-fermion approach to finite temperatures to understand the charge dynamics and melting process of the two-dimensional Mott insulator, revealing the role of spin fluctuations and the emergence of a pseudogap.

Contribution

It provides a comprehensive finite-temperature theory of the Mott insulator that matches quantum Monte Carlo results and explains the pseudogap formation during insulator melting.

Findings

Quantitative agreement with quantum Monte Carlo simulations.

Short-ranged spin fluctuations induce holon-doublon bound states.

The Mott gap closes before the charge gap, leading to a pseudogap.

Abstract

The Mott insulator is the quintessential strongly correlated electronic state. We obtain complete insight into the physics of the two-dimensional Mott insulator by extending the slave-fermion (holon-doublon) description to finite temperatures. We first benchmark its predictions against state-of-the-art quantum Monte Carlo simulations, demonstrating quantitative agreement. Qualitatively, the short-ranged spin fluctuations both induce holon-doublon bound states and renormalize the charge sector to form the Hubbard bands. The Mott gap is understood as the charge gap renormalized downwards by these spin fluctuations. As temperature increases, the Mott gap closes before the charge gap, causing a pseudogap regime to appear naturally during the melting of the Mott insulator.