Charge screening and magnetic anisotropy in metallic rare-earth systems

TL;DR

This paper investigates how non-uniform electron densities, especially Friedel oscillations, influence magnetic anisotropy and crystal fields in metallic rare-earth systems, challenging traditional models and providing new insights.

Contribution

It introduces a method to calculate magnetic anisotropy constants considering continuous charge distributions and demonstrates the significant impact of Friedel oscillations on crystal field formation.

Findings

Friedel oscillations can alter the effective ion charge and even reverse its sign.

The approach justifies the use of the anion model in hydrogen-containing systems.

Implications for magnetic structure deformation near interstitial muons are discussed.

Abstract

The calculation of magnetic anisotropy constants is performed beyond the point charge model for a continuous charge density distribution of screening conduction electrons. An important role of the non-uniform electron density, in particular, of the Friedel oscillations, in the formation of crystal field is demonstrated. Such effects can modify strongly the effective ion (impurity) charge and even change its sign. This enables one to justify the anion model, which is often used at discussing experimental data on hydrogen-containing systems. Possible applications to the pure rare-earth metals and RCo5 compounds are discussed. The deformation of magnetic structure near the interstitial positive muon owing to the strong local anisotropy, and the corresponding contribution to the dipole field at the muon are considered.