Observation of a charge-neutral muon-polaron complex in antiferromagnetic Cr2O3

We report a comprehensive muon spin rotation (μSR) study of the prototypical magnetoelectric antiferromagnet Cr2O3. 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 μSR 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. © Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license.

Keywords

Antiferromagnetism, Muon spin relaxation, Chromium, Ozone, Spin, Hydrogen, Materials

Citation

Dehn, M. H., Shenton, J. K., Holenstein, S., Meier, Q. N., Arseneau, D. J., Cortie, D. L., Hitti, B., Fang, A. C. Y., MacFarlane, W. A., McFadden, R. M. L., Morris, G. D., Salman, Z., Luetkens, H., Spaldin, N. A., Fechner, M., & Kiefl, R. F. (2020). Observation of a charge-neutral muon-polaron complex in antiferromagnetic Cr2O3. Physical Review X, 10(1), 011036. doi:10.1103/PhysRevX.10.011036