Poisoning of magnetism in silicon doped with Re, caused by a charge transfer from interstitials to substitutionals, by means of the self-interaction corrected density-functional approach

TL;DR

This study uses self-interaction corrected density-functional calculations to investigate how charge transfer between interstitial and substitutional Re impurities in silicon affects magnetism, revealing that doping can restore magnetic properties.

Contribution

It demonstrates how charge transfer between Re impurities influences magnetism in silicon and shows doping can revive magnetism suppressed by impurity interactions.

Findings

Re impurities form loosely bound pairs in silicon.

Charge transfer makes Re sites nonmagnetic.

Doping can restore magnetism in Re-doped silicon.

Abstract

The self-interaction corrected density-functional calculations are performed for Re impurities and their pairs in silicon. Rhenium ions form in the host crystal not very tight pairs, with impurities separated by one Si atom or by a distance close to two silicon bonds. Comparison of formation energies for various pairs of substitutionals, interstitials, and mixed-site impurities favours the last type. Electron transfer from the interstitial into the substitutional impurity makes the both Re sites nonmagnetic, but the p-type and the n-type co-doping revives magnetism again, the latter more efficiently.