Magnetic structure of S = 1 dimer compound K2Ni2(SeO3)3

Topological structure plays a crucial role in the magnetism of quantum magnets. The S = 1 antiferromagnet K2Ni2(SeO3)3 has a triangular-lattice structure composed of perpendicular-to-plane Ni2 dimers. Surprisingly, K2Ni2(SeO3)3 exhibits two-step antiferromagnetic transitions at TN1 and TN2, whose values are magnetic-field dependent, and a 1/3 magnetization plateau at 2 K, which is typical for triangular-lattice antiferromagnet rather than the S =1 dimer compound. We propose to collect NPD data to determine the nature of the observed magnetic transitions and to shed more light on why the compound behaves like a TLAF rather than a spin-dimer antiferromagnet.