Pseudogap isotope effect as a probe of bipolaron mechanism in high temperature superconductors

TL;DR

This paper develops a theory for the pseudogap phase in high-temperature superconductors, linking bipolaron mechanisms to isotope effects and predicting experimental outcomes including negative isotope coefficients.

Contribution

It introduces a bipolaron-based model for the pseudogap phase and calculates the isotope coefficient, aligning with experimental observations and proposing new experimental tests.

Findings

Calculated transition temperature T* for pseudogap phase.

Predicted isotope coefficient, including negative values.

Suggested experiments on magnetic field effects.

Abstract

A theory of a pseudogap phase of high-temperature superconductors where current carriers are translation invariant bipolarons is developed. A temperature T* of a transition from a pseudogap phase to a normal one is calculated. For the temperature of a transition to the pseudogap phase, the isotope coefficient is found. It is shown that the results obtained, in particular, the possibility of negative values of the isotope coefficient are consistent with the experiment. New experiments on the influence of the magnetic field on the isotope coefficient are proposed.