Abstract
A comprehensive set of muon spin spectroscopy and neutron scattering measurements supported by ab initio and model Hamiltonian simulations have been used to investigate the magnetic ground state of Na2PrO3. μSR reveals a Néel antiferromagnetic order below TN∼4.9K, with a small static magnetic moment mstatic≤0.22μB/Pr collinearly aligned along the c axis. Inelastic neutron measurements reveal the full spectrum of crystal field excitations and confirm that the Pr4+ ground-state wave function deviates significantly from the Γ7 limit that is relevant to the Kitaev model. Single- and two-magnon excitations are observed in the ordered state below TN=4.6K and are well described by nonlinear spin wave theory from the Néel state using a magnetic Hamiltonian with Heisenberg exchange J=1meV and symmetric anisotropic exchange Γ/J=0.1, corresponding to an XY model. Intense two magnon excitations are accounted for by g-factor anisotropy gz/g±=1.29. A fluctuating moment δm2=0.57(22)μB2/Pr extracted from the energy and momentum integrated inelastic neutron signal is reduced from expectations for a local J=1/2 moment with average g factor gavg≈1.1. Together, the results demonstrate that the small moment in Na2PrO3 arises from crystal field and covalency effects and the material does not exhibit significant quantum fluctuations.
| Original language | English |
|---|---|
| Article number | 064425 |
| Journal | Physical Review B |
| Volume | 110 |
| Issue number | 6 |
| DOIs | |
| State | Published - Aug 1 2024 |
Funding
K.W.P and Q.W. were supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Grant No. DE-SC0021223. V.F.M. was supported by the National Science Foundation under Grant No. DMR-1905532. J.G.R. was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) (Funding Reference No. RGPIN-2020-04970). Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. I.J.O. and P.B. acknowledge financial support from PNRR MUR project ECS-00000033-ECOSISTER and also acknowledge computing resources provided by the STFC scientific computing department's SCARF cluster and CINECA award under the ISCRA (Project ID IsCa4) initiative.