The Feshbach resonance and nanoscale phase separation in a polaron liquid near the quantum critical point for a polaron Wigner crystal

TL;DR

This paper investigates the interplay between Feshbach resonance, nanoscale phase separation, and quantum criticality in a polaron liquid near a polaron Wigner crystal transition, highlighting the role of microstrain in cuprates.

Contribution

It identifies a competing electronic crystal of pseudo Jahn-Teller polarons as a long-range order parameter near the quantum critical point in cuprates.

Findings

Microstrain correlates with quantum critical fluctuations.

Polaron Wigner crystal phase competes with superconductivity.

Variation of spin gap energy supports polaronic phase transition.

Abstract

The additional long range order parameter that competes with the high Tc superconductivity long range order is identified as an electronic crystal of pseudo Jahn-Teller polarons beyond the critical value of the electron lattice interaction. We show that the region of quantum critical fluctuations in the two variables phase diagram of cuprates: the doping (delta) and the chemical pressure (i.e., the tolerance factor, or the average ionic radius of A-site cations) can be measured via the microstrain (eta) of the Cu-O length in the CuO2 lattice. The fluctuating order in the proximity of the microstrain quantum critical point that competes with the superconducting long range order is the polaron electronic crystalline phase called a Wigner polaron crystal and the variation of the spin gap energy as a function of microstrain provides a strong experimental support for this proposal.