A μ⁺ SR study of the rare earth antiferromagnet PrO₂

We present zero-field muon spin relaxation (μ+SR) measurements on the rare earth antiferromagnet PrO2. Oscillations in the time dependence of the muon polarization, characteristic of a quasistatic magnetic field at two distinct muon sites, are observed below TN, along with relaxation dominated by the magnitude of the local field. Candidate muon sites in the material are suggested on the strength of dipole field calculations. Relaxation above TN allows a prediction of the quasielastic neutron scattering linewidth, which is discussed in terms of a simple model of magnetoelastic relaxation involving a crystal field state at an energy Δ above the ground level. The obtained value of Δ may be taken as an approximate estimate of the splitting of the Γ8 ground state of Pr4+ in the distorted fluorite structure