Mott physics, sign structure, ground state wavefunction, and high-Tc superconductivity

TL;DR

This paper explores how doping transforms antiferromagnetic Mott insulators into high-temperature superconductors, emphasizing the role of altered statistical signs, spin correlations, and the pseudogap phenomenon in the phase transition.

Contribution

It provides a pedagogical framework connecting Mott physics, sign structure, and superconductivity, highlighting the importance of statistical sign changes upon doping.

Findings

Superconductivity emerges when spin correlations become short-ranged.

The pseudogap appears as a crossover between antiferromagnetic and superconducting phases.

High-temperature strange metal phase exhibits maximum mutual statistical interaction.

Abstract

In this article I give a pedagogical illustration of why the essential problem of high-Tc superconductivity in the cuprates is about how an antiferromagnetically ordered state can be turned into a short-range state by doping. I will start with half-filling where the antiferromagnetic ground state is accurately described by the Liang-Doucot-Anderson (LDA) wavefunction. Here the effect of the Fermi statistics becomes completely irrelevant due to the no double occupancy constraint. Upon doping, the statistical signs reemerge, albeit much reduced as compared to the original Fermi statistical signs. By precisely incorporating this altered statistical sign structure at finite doping, the LDA ground state can be recast into a short-range antiferromagnetic state. Superconducting phase coherence arises after the spin correlations become short-ranged, and the superconducting phase transition is controlled by spin excitations. I will stress that the pseudogap phenomenon naturally emerges as a crossover between the antiferromagnetic and superconducting phases. As a characteristic of non Fermi liquid, the mutual statistical interaction between the spin and charge degrees of freedom will reach a maximum in a high-temperature "strange metal phase" of the doped Mott insulator.