Understanding the mu SR spectra of MnSi without magnetic polarons

Abstract

Transverse-field muon-spin rotation (ISR) experiments were performed on a single crystal sample of the noncentrosymmetric system MnSi. The observed angular dependence of the muon precession frequencies matches perfectly the one of the Mn-dipolar fields acting on the muons stopping at a 4a position of the crystallographic structure. The data provide a precise determination of the magnetic dipolar tensor. In addition, we have calculated the shape of the field distribution expected below the magnetic transition temperature TC at the 4a muon site when no external magnetic field is applied. We show that this field distribution is consistent with the one reported by zero-field ISR studies. Finally, we present ab initio calculations based on the density-functional theory which confirm the position of the muon stopping site inferred from transverse field ISR. In view of the presented evidence we conclude that the ISR response of MnSi can be perfectly and fully understood without invoking a hypothetical magnetic polaron state. © 2014 American Physical Society.