# Electronic diffusion in a normal state of high-Tc cuprate YBa2Cu3O6+x

## TL;DR

This paper investigates electronic diffusion in high-temperature superconducting cuprates using heat transport and resistivity measurements.

## Contribution

The study provides new insights into incoherent transport and charge susceptibility effects in underdoped cuprates.

## Key findings

- Electronic diffusion shows strongly incoherent transport in underdoped samples.
- Mean free path reaches the MIR limit above ~200 K in underdoped samples.
- Charge susceptibility significantly affects resistivity in YBa2Cu3O6+x.

## Abstract

The bad metallic phase with resistivity above the Mott–Ioffe–Regel (MIR) limit, which appears also in cuprate superconductors, was recently understood by cold atom and computer simulations of the Hubbard model via charge susceptibility and charge diffusion constant. However, since reliable simulations can be typically done only at temperatures above the experimental temperatures, the question for cuprate superconductors is still open. This paper addresses this question by resorting to heat transport, which allows for the estimate of electronic diffusion and it further combines it with the resistivity to estimate the charge susceptibility. The doping and temperature dependencies of diffusion constant and charge susceptibilities are shown and discussed for two samples of YBa2Cu3O6+x. Results indicate strongly incoherent transport, mean free path corresponding to the MIR limit for the underdoped sample at temperatures above ~200 K and significant effect of the charge susceptibility on the resistivity.