Site determination of positive muons in Pr single crystal

Abstract Pr, with a dhcp crystal structure, possesses a strongly anisotropic bulk magnetic susceptibility χ . The temperature dependencies of χ ∥ (applied magnetic field H ext parallel to c axis) and χ ⊥ (field perpendicular to c axis) are quite different; they can be described by two distinct Curie–Weiss forms at high temperature. Transverse-field (TF) μSR measurements have been performed in a single-crystal Pr sample. In the studied temperature range (1.8≤ T ≤300 K), depending on the crystal orientation in H ext , a single frequency precession signal is obtained, from which the two principal Knight-shift ( K μ ) components can be determined. For H ext ⊥ c a linear scaling between K μ and χ is found for the entire T range. For H ext ∥ c a linear scaling is only observed above 50 K. From these K μ vs. χ relations the axial dipolar-coupling tensor A D is deduced. Candidates for hosting the μ + in Pr are e sites and f sites (Wyckoff notation) of the P 6 3 / mmc crystal structure. For both sites we have calculated the dipolar-coupling tensor, and found an agreement with the measurements only for the f sites (octahedral interstices). Thus it appears that the muon resides at f sites.