Pseudogap in Doped Mott Insulators is the Near-neighbour Analogue of the Mott Gap

TL;DR

This paper demonstrates that the pseudogap in doped Mott insulators originates from strong coupling effects related to the Mott gap, caused by energy barriers for transport near singly-occupied sites not adjacent to holes.

Contribution

It reveals that the pseudogap arises from local energy barriers in doped Mott insulators, providing a simple explanation for its ubiquity in cuprates.

Findings

Doping causes a jump in chemical potential.

A pseudogap appears below a characteristic temperature.

The pseudogap is linked to local energy barriers of order t^2/U.

Abstract

We show that the strong coupling physics inherent to the insulating Mott state in 2D leads to a jump in the chemical potential upon doping and the emergence of a pseudogap in the single particle spectrum below a characteristic temperature. The pseudogap arises because any singly-occupied site not immediately neighbouring a hole experiences a maximum energy barrier for transport equal to $t^2/U$, where $t$ is the nearest-neighbour hopping integral and $U$ the on-site repulsion. The resultant pseudogap cannot vanish before each lattice site, on average, has at least one hole as a near neighbour. The ubiquituity of this effect in all doped Mott insulators suggests that the pseudogap in the cuprates has a simple origin.