We report a neutron scattering study of the metallic triangular lattice antiferromagnet PdCrO2. Powder neutron diffraction measurements confirm that the crystalline space group symmetry remains R3ˉm below TN. This implies that magnetic interactions consistent with the crystal symmetry do not stabilise the non-coplanar magnetic structure which was one of two structures previously proposed on the basis of single crystal neutron diffraction measurements. Inelastic neutron scattering measurements find two gaps at low energies which can be explained as arising from a dipolar-type exchange interaction. This symmetric anisotropic interaction also stabilises a magnetic structure very similar to the coplanar magnetic structure which was also suggested by the single crystal diffraction study. The higher energy magnon dispersion can be modelled by linear spin wave theory with exchange interactions up to sixth nearest-neighbors, but discrepancies remain which hint at additional effects unexplained by the linear theory.
@article{arxiv.1804.05573,
title = {Magnetic interactions in PdCrO$_2$ and their effects on its magnetic structure},
author = {Manh Duc Le and Seyyoung Jeon and A. I. Kolesnikov and D. J. Voneshen and A. S. Gibbs and Jun Sung Kim and Jinwon Jeong and Han-Jin Noh and Changhwi Park and Jaejun Yu and T. G. Perring and Je-Geun Park},
journal= {arXiv preprint arXiv:1804.05573},
year = {2018}
}