Abstract
The ground-state magnetic structure of was investigated by single-crystal neutron diffraction. At base temperature, the moments are found to form an incommensurate antiferromagnetic spiral-like structure with a magnetic propagation vector of . They align ferromagnetically in the plane with the moment size of 6.75(6) , but rotate spirally by around the axis from layer to layer. The magnetic order parameter in the critical region close to the ordering temperature K shows critical behavior with a critical exponent of , consistent with the three-dimensional Heisenberg model. Moreover, within the experimental uncertainty, our neutron data are consistent with a model in which the Ni sublattice is not magnetically ordered.
- Received 19 November 2018
- Revised 13 January 2019
DOI:https://doi.org/10.1103/PhysRevB.99.014425
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