Magnetic structure and crystal field states of Pr2 Pd3 Ge5: μsR and neutron scattering investigations

We present the results of muon spin relaxation (μSR), neutron powder diffration (NPD), and inelastic neutron scattering (INS) investigations on polycrystalline Pr2Pd3Ge5. The polycrystalline Pr2Pd3Ge5 is known to exhibit two antiferromagnetic transitions near TN1=8.3 K and TN2=7.5 K which is confirmed by the heat capacity measurements on the present sample. In the magnetically ordered state the NPD data show clear evidence for magnetic Bragg peaks, which for T<TN2 could be indexed with a propagation vector k = (1, 0, 0), and with k = (1, 0, 0.07) for TN2<T<TN1. We have determined the magnetic structure and found a canted antiferromagnetic structure of ordered Pr3+ moments. At 7.6 K we find an amplitude modulated incommensurate antiferromagnetic arrangement of ordered moments with a maximum ordered moment of 1.64(3) μB/Pr lying in the ab plane tilted at about 26∘ from the b axis. At 1.8 K the antiferromagnetic structure is found to be commensurate with an ordered moment of 2.80(6) μB/Pr lying in the ab plane tilted at about 28∘ from the b axis. Our zero-field μSR spectra at 1.5 K and at shorter time scale (below 0.5 μs) reveal two oscillatory frequencies further supporting a long-range-ordered magnetic ground state. We have calculated the muon sites using the density functional theory calculation and present the results of internal field calculations at the muon stopping sites, which are in good agreement with the experimental observations. In the paramagnetic state, the INS data show three well defined CEF excitations near 8.0, 12.3, and 18.1 meV arising from the crystal electric field (CEF) split J=4 ground state of Pr3+. The CEF level scheme is deduced by analyzing the INS data by a model based on the CEF model.