Correlation-enhanced Friedel oscillations in amorphous and quasicrystalline metals

TL;DR

This paper demonstrates that electron-electron interactions and quantum correlations can enhance Friedel oscillations in amorphous and quasicrystalline metals, aiding their stabilization at finite temperatures.

Contribution

It reveals how electron correlations induce a power-law divergence in the density response, enhancing Friedel oscillations and supporting Hume-Rothery stabilization at T>0.

Findings

Friedel oscillations are enhanced by electron correlations.

A power-law divergence in the density response occurs at q=2k_F.

The spatial decay of oscillations is reduced, supporting stabilization mechanisms.

Abstract

The exponentially strong damping of the conventional Friedel oscillations at elevated temperature T as well as due to disorder poses a severe problem to the Hume-Rothery (HR) stabilization mechanism of amorphous and quasicrystalline alloys. We show that quantum correlations induced by electron-electron interactions in the presence of random impurity scattering can play an important role in stabilizing these systems: When there is strong backscattering off local ion clusters, the static electron density response chi(0,q) acquires a powerlaw divergence at q=2k_F even at T>0. This Fermi surface singularity leads to an enhancement as well as to a systematical phase shift of the Friedel oscillations, consistent with experiments. In addition, the spatial decay exponent is reduced, strongly supporting the validity of a HR-like mechanism at T>0. This effect may be accounted for in pseudopotential calculations through the local field factor.