Pseudogap state of underdoped cuprate HTSC as a display of the Jahn-Teller pseudoeffect

TL;DR

This paper proposes that the pseudogap state in underdoped cuprate high-temperature superconductors arises from a Jahn-Teller pseudoeffect involving two-site Jahn-Teller polarons, linking electronic states and symmetry breaking phenomena.

Contribution

It introduces a novel explanation for the pseudogap state based on Jahn-Teller pseudoeffect and two-site polarons within a two-component charge carrier model.

Findings

Two near-degenerate electronic states are identified in the copper-oxygen plane.

The Jahn-Teller pseudoeffect explains the pseudogap as a dynamic vibronic phenomenon.

Broken time-reversal symmetry is consistent with the two-site Jahn-Teller polaron model.

Abstract

For underdoped cuprate HTSC within the framework of the two component model of charge carries (holes and Zhang-Rice polarons) it is considered two near degenerate states of hole molecular orbitals in copper-oxygen plane. These are the state of hole molecular orbitals around one-site Zhang-Rice polarons, and another state is two-site hole molecular orbitals around the two-site oxygen cluster of two nearest Jahn-Teller copper ions with antiferromagnetic ordering spins and with common oxygen ion. Taking into account that the vibronic mixing of these near-degenerate electronic states leads to the Jahn-Teller dynamic effect, in this paper the supposition that the pseudogap state is a consequence of the Jahn-Teller pseudoeffect is discussed. It is shown that existence of two-site Jahn-Teller polaron is consistent with a recent observation of broken time-reversal symmetry in the pseudogap state.