Bonf, PietroOnuorah, Ifeanyi JohnLang, FranzTimrov, IuriiMonacelli, LorenzoWang, ChennanSun, XiaoPetracic, OlegPizzi, GiovanniMarzari, NicolaBlundell, Stephen J.De Renzi, Roberto2024-05-162024-05-162024-05-162024-01-2410.1103/PhysRevLett.132.046701https://infoscience.epfl.ch/handle/20.500.14299/207901WOS:001185766500003Magnetostriction results from the coupling between magnetic and elastic degrees of freedom. Though it is associated with a relatively small energy, we show that it plays an important role in determining the site of an implanted muon, so that the energetically favorable site can switch on crossing a magnetic phase transition. This surprising effect is demonstrated in the cubic rocksalt antiferromagnet MnO which undergoes a magnetostriction-driven rhombohedral distortion at the Neel temperature T-N = 118 K. Above T-N, the muon becomes delocalized around a network of equivalent sites, but below T-N the distortion lifts the degeneracy between these equivalent sites. Our first-principles simulations based on Hubbard-corrected density-functional theory and molecular dynamics are consistent with the 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.Physical SciencesLongitudinal Spin RelaxationRange-Magnetic-OrderPhase-TransitionsPositive MuonMnoCooNioPseudopotentialsDiffractionDynamicstext::journal::journal article::research article