Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide

TL;DR

This study demonstrates that magnetostriction in MnO causes a lattice distortion that localizes implanted muons below the Néel temperature, with first-principles simulations supporting experimental observations and offering insights into muon behavior in magnetic oxides.

Contribution

It reveals how magnetostriction-induced distortion in MnO localizes muons, combining experimental data with first-principles simulations to explain muon site behavior in magnetic oxides.

Findings

Magnetostriction causes rhombohedral distortion in MnO at T_N.

Muon localization occurs below T_N due to lattice distortion.

Simulations align with experimental muon precession data.

Abstract

Magnetostriction drives a rhombohedral distortion in the cubic rock salt antiferromagnet MnO at the N\'eel temperature $T_{N}=118$ K. As an unexpected consequence we show that this distortion acts to localize the site of an implanted muon due to the accompanying redistribution of electron density. This lifts the degeneracy between equivalent sites, resulting in a single observed muon precession frequency. Above $T_{N}$, the muon instead becomes delocalized around a network of equivalent sites. Our first-principles simulations based on Hubbard-corrected density-functional theory and molecular dynamics are consistent with our experimental data and help to resolve a long-standing puzzle regarding muon data on MnO, as well as having wider applicability to other magnetic oxides.