Magnetic structure of the conductive triangular-lattice antiferromagnet PdCrO2

We performed neutron single-crystal and synchrotron x-ray powder diffraction experiments in order to investigate the magnetic and crystal structures of the conductive layered triangular-lattice antiferromagnet PdCrO2 with a putative spin chirality, which contributes to an unconventional anomalous Hall effect. We revealed that the ground-state magnetic structure is a commensurate and nearly coplanar 120 degrees spin structure. The 120 degrees planes in different Cr layers seem to tilt with one another, leading to a small noncoplanarity. Such a small but finite noncoplanar stacking of the 120 degrees planes gives rise to a finite scalar spin chirality, which may be responsible for the unconventional nature of the Hall effect of PdCrO2.