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arXiv · 1909.00416

Observation of a charge-neutral muon-polaron complex in antiferromagnetic Cr$_2$O$_3$

M. H. Dehn·J. K. Shenton·S. Holenstein·Q. N. Meier·D. J. Arseneau·D. L. Cortie·B. Hitti·A. C. Y. Fang·W. A. MacFarlane·R. M. L. McFadden·G. D. Morris·Z. Salman·H. Luetkens·N. A. Spaldin·M. Fechner·R. F. Kiefl
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Abstract

We report a comprehensive muon spin rotation ($μ$SR) study of the prototypical magnetoelectric antiferromagnet Cr$_2$O$_3$. We find the positively charged muon ($μ^+$) occupies several distinct interstitial sites, and displays a rich dynamic behavior involving local hopping, thermally activated site transitions and the formation of a charge-neutral complex composed of a muon and an electron polaron. The discovery of such a complex has implications for the interpretation of $μ$SR spectra in a wide range of magnetic oxides, and opens a route to study the dopant characteristics of interstitial hydrogen impurities in such materials. We address implications arising from implanting a $μ^+$ into a linear magnetoelectric, and discuss the challenges of observing a local magnetoelectric effect generated by the charge of the muon.

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M. H. Dehn, J. K. Shenton, S. Holenstein, Q. N. Meier, D. J. Arseneau, D. L. Cortie, B. Hitti, A. C. Y. Fang, W. A. MacFarlane, R. M. L. McFadden, G. D. Morris, Z. Salman, H. Luetkens, N. A. Spaldin, M. Fechner, R. F. Kiefl. 2019-09-01. Observation of a charge-neutral muon-polaron complex in antiferromagnetic Cr$_2$O$_3$. https://doi.org/10.1103/physrevx.10.011036

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