Abstract
A neutron powder diffraction (NPD) study of ( or Ce) reveals differences between the magnetic ground state of the two compounds due to the strong Ce-Mn coupling compared to La-Mn. The two compounds adopt the P4/nmm space group down to 2 K, and whereas magnetization measurements do not show obvious anomaly at high temperatures, NPD reveals a C-type antiferromagnetic (AFM) order below for LaMnSbO and 240 K for CeMnSbO. While the magnetic structure of LaMnSbO is preserved to base temperature, a sharp transition at is observed in CeMnSbO due to a spin-reorientation (SR) transition of the magnetic moments from pointing along the axis to the plane. The SR transition in CeMnSbO is accompanied by a simultaneous long-range AFM ordering of the Ce moments, which indicates that the Mn SR transition is driven by the Ce-Mn coupling. The ordered moments are found to be somewhat smaller than those expected for () in insulators, but large enough to suggest that these compounds belong to the class of local-moment antiferromagnets. The lower found in these two compounds compared to the As-based counterparts ( for LaMnAsO, for CeMnAsO) indicates that the Mn- ( or Sb) hybridization that mediates the superexchange Mn--Mn coupling is weaker for the Sb-based compounds.
- Received 14 December 2015
DOI:https://doi.org/10.1103/PhysRevB.93.094413
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