Magnetic structure of new ordered honeycomb compounds MPtI6 (M = Fe, Co, Ni)

We aim to analyze magnetic structure of new layered honeycomb compounds MPtI6 (M = Fe, Co Ni). In MPtI6, M2+ and nonmagnetic Pt4+ ions form BN-type ordered arrangement, which results in a triangular lattice of M2+ ions. All MPtI6 show antiferromagnetic order at low temperatures. MPtI6 are expected to possess unconventional magnetic interaction due to spin-orbital entanglement of M2+ ions and strong spin-orbit coupling of iodine. The analysis of magnetic structure should provide us with insights into the underlying magnetic interactions. We propose to perform neutron diffraction measurements on the three MPtI6 sample at WISH and request 2days beamtime.