Friedel crystals and the outer crust of magnetars

TL;DR

This paper explores how Friedel oscillations influence the crystal structure of the outer crust in magnetars under strong magnetic fields, affecting their physical properties and stability.

Contribution

It introduces the concept of Friedel crystals in magnetar crusts, analyzing their formation conditions and calculating their elastic and phonon properties.

Findings

Friedel oscillations can dominate ion interactions in magnetar crusts.

The paper estimates the density and magnetic field ranges for Friedel crystal formation.

Elastic moduli and phonon dispersion relations are computed for these crystals.

Abstract

The strong magnetic fields found on the surface of magnetars are known to have profound effects in the physics of atoms in magnetar envelopes. We argue that the Friedel oscillations in the Coulomb force between the ions due to electron shielding can, for certain values of the parameters, be the dominant effect determining the crystal structure in the outer crust of magnetars. We estimate the densities and magnetic fields for which this occurs, compute some of the elastic moduli and lattice phonon dispersion relations in this "Friedel crystal" phase.