Magnetic structure and properties of orthorhombic Li2Ni(SO4)2: A possible magnetoelectric material

In this paper, we report on the structural and magnetic properties, as deduced from susceptibility measurements and neutron powder diffraction experiments, of an orthorhombic nickel disulfate, Li2Ni(SO4)(2). This phase presents NiO6 octahedra linked via SO4 groups only, leading to an antiferromagnetic behavior resulting from super-super-exchange interactions. Magnetic moments order below T-N = 28 K and the observed magnetic structure can be explained using two antiferromagnetic and one ferromagnetic exchange interactions, which are discussed in relation with the Goodenough-Kanamori-Anderson rules. The magnetic structure, with k = (0, 0, 0), has the symmetry Pb'c'a' that has the inversion center associated with time inversion, so the compound should be a linear magnetoelectric.