Variational study of conduction in doped Mott insulator in terms of kinetic energy

TL;DR

This study investigates how doped holes in the Hubbard model contribute to conduction and superconductivity, revealing two distinct roles of holes related to localization and itinerancy in doped Mott insulators.

Contribution

It introduces a variational Monte Carlo approach to classify doped holes' roles in conduction and superconductivity within the Hubbard model.

Findings

Holes in doublon-holon pairs are localized and promote superconductivity.

Doped holes can become itinerant carriers, leading to metallic or superconducting states.

The dual roles of holes are common in antiferromagnetic transitions at large U/t.

Abstract

The kinetic features of holes (electrons) in the Hubbard model are studied using a variational Monte Carlo method. In doped Mott insulators (U>U_co), holes are classified, in the sense of conduction, into two categories: (i) The holes appearing in doublon-holon pairs are localized, encourage singlet pair formation, and gain the energy to induce a superconducting transition. (ii) The doped holes become carriers, make the system itinerant (superconducting or metallic), but lose the energy in the transition. These two roles are distinguished in correlated superconductivity. This feature is common to antiferromagnetic transitions at large U/t.