Well resolved multifrequency ${\mathrm{\mu }}^{+}$ spin-resonance spectra were observed as function of field direction and temperature in a single crystal of ${\mathrm{PrNi}}_5$. Two interstitial ${\mathrm{\mu }}^{+}$ positions were identified. A ${\mathrm{P}}_{\mathrm{x}}$(cosθ) term, in addition to ${\mathrm{A}}_0$, is sufficient to describe the angular dependence. Neither the angular dependence nor the temperature dependence of the shifts can be accounted for by Pr magnetic moments. Evidence is provided for magnetic moments at Ni sites, contradicting prevailing views.

• Received 4 October 1988

DOI:https://doi.org/10.1103/PhysRevLett.62.2732