Universal Diffusion in Coulomb Crystals

TL;DR

This paper introduces a universal model for diffusion in Coulomb crystals, revealing that diffusion is independent of screening and vacancy formation is significant, contrary to previous beliefs.

Contribution

The study presents a universal scaling law for diffusion in Coulomb crystals and demonstrates the importance of vacancy formation and hole diffusion.

Findings

Diffusion follows a universal scaling independent of screening.

Vacancy formation is not suppressed by high pressure.

Vacancy and hole diffusion dominate self diffusion in Coulomb crystals.

Abstract

Diffusion coefficients for crystallized Coulomb plasmas are essential microphysics input for modeling white dwarf cores and neutron star crusts but are poorly understood. In this work we present a model for diffusion in Coulomb crystals. We show that melting and diffusion follow the same universal scaling such that diffusion is independent of screening. Our simulations show, contrary to prevailing wisdom, that the formation of vacancies is not suppressed by the large pressure. Rather, vacancy formation and hole diffusion is the dominant mode of self diffusion in Coulomb crystals.