Muon sites in PbF2 and YF3: decohering environments and the role of anion Frenkel defects

TL;DR

This paper investigates muon sites in ionic fluorides PbF2 and YF3, showing how muon spin decoherence reveals local environments and defects, including Frenkel defects, aiding phase identification.

Contribution

It introduces a method to determine muon sites and detect anion Frenkel defects in ionic fluorides using muon spin decoherence analysis.

Findings

Identification of muon sites in PbF2 and YF3

Detection of anion Frenkel defects in PbF2

Distinction between different crystal phases

Abstract

Muons implanted into ionic fluorides often lead to a so-called F-mu-F state, in which the time evolution of the muon spin contains information about the geometry and nature of the muon site. Nuclei more distant from the muon than the two nearest-neighbor fluorine ions result in decoherence of the F-mu-F system and this can yield additional quantitative information about the state of the muon. We demonstrate how this can be applied to the determination of muon sites within the ionic fluorides alpha-PbF2 and YF3 which contain fluoride ions in different crystallographic environments. Our results can be used to distinguish between different crystal phases and reveal the presence of anion Frenkel defects in alpha-PbF2.