d-wave pairing in lightly doped Mott insulators

TL;DR

This paper introduces a new measure, $Z_c$, to quantify electron pairing strength, revealing d-wave pairing in lightly doped Mott insulators through numerical analysis of the Hubbard model.

Contribution

It defines and applies the $Z_c$ quantity to demonstrate d-wave pairing in lightly doped Mott insulators, highlighting a new correlation-driven feature.

Findings

Finite $Z_c$ with d-wave symmetry at half filling and light doping

Electronic correlations induce pairing not captured by single-particle theories

Method confirms pairing in strongly correlated electron systems

Abstract

We define a suitable quantity $Z_c$ that measures the pairing strength of two electrons added to the ground state wave function by means of the anomalous part of the one-particle Green's function. $Z_c$ discriminates between systems described by one-electron states, like ordinary metals and band insulators, for which $Z_c=0$, and systems where the single particle picture does not hold, like superconductors and resonating valence bond insulators, for which $Z_c \ne 0$. By using a numerically exact projection technique for the Hubbard model at $U/t=4$, a finite value of $Z_c$, with d-wave symmetrry, is found at half filling and in the lightly doped regime, thus emphasizing a qualitatively new feature coming from electronic correlation.