Using neutron-scattering techniques, we have investigated the nuclear and the magnetic structures of the triangular antiferromagnet 3R-AgNiO2. The symmetry analysis based on the group theory suggests that the √3×√3 charge order proposed for 2H -AgNiO2 will have a monoclinic symmetry if present in the trigonal lattice of 3R-AgNiO 2. The Rietveld refinement shows that symmetry reduction in the NiO2 layer is consistent with the prediction of the group theory. The pair density function consistently shows that the nearest-neighbor Ni-O bonds split into two groups separated by approximately 0.1 Å. The antiferromagnetic Bragg peaks observed below TN=25 K can be described by the propagation vector k= (0,1,0) of the monoclinic unit cell. The similarities of the local structure and the antiferromagnetic order strongly suggest that the novel charge order observed in 2H-AgNiO2 also exists in 3R-AgNiO2.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2008 Dec 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics