Magnetic excitations in a spin-liquid candidate K2Ni2(SO4)3

In majority of magnetic compounds interactions between spins, that reside on magnetic ions, result in a long-range ordered state below a critical temperature. In some materials spins are arranged in triangles, which when coupled with antiferromagnetic interaction results in a strongly correlated magnetic system without long-range order (spin-liquids). Majority of research has been devoted to quasi-2D, S=1/2 systems, where quantum fluctuations are expected to play a dominant role. The title compound is different in several ways: i) Ni ions support S=1, which still allows significant quantum corrections, ii) it is a 3D system (cubic space group) without an inversion center (non-trivial topological properties) and iii) triangles form a network of pentagons, which increases the level of frustration. We wish to explore magnetic excitations in this system using inelastic neutron scattering.