Non-collinear magnetism in the post-perovskite thiocyanate frameworks CsM(NCS)3

AMX(3) compounds are structurally diverse, a notable example being the post-perovskite structure which adopts a two-dimensional framework with corner- and edge-sharing octahedra. Few molecular post-perovskites are known and of these, none have reported magnetic structures. Here we report the synthesis, structure and magnetic properties of molecular post-perovskites: CsNi(NCS)(3), a thiocyanate framework, and two new isostructural analogues CsCo(NCS)(3) and CsMn(NCS)(3). Magnetisation measurements show that all three compounds undergo magnetic order. CsNi(NCS)(3) (Curie temperature, T-C = 8.5(1) K) and CsCo(NCS)(3) (T-C = 6.7(1) K) order as weak ferromagnets. On the other hand, CsMn(NCS)(3) orders as an antiferromagnet (Neel temperature, T-N = 16.8(8) K). Neutron diffraction data of CsNi(NCS)(3) and CsMn(NCS)(3), show that both are non-collinear magnets. These results suggest molecular frameworks are fruitful ground for realising the spin textures required for the next generation of information technology.

Automated summary

AMX(3) compounds exhibit diverse structures, including the two-dimensional post-perovskite structure with corner- and edge-sharing octahedra. Molecular post-perovskites are rare and none have reported magnetic structures. Here, we report the synthesis, structure, and magnetic properties of CsNi(NCS)(3), CsCo(NCS)(3), and CsMn(NCS)(3), which are molecular post-perovskites. Magnetisation measurements reveal that all three compounds exhibit magnetic ordering, with CsNi(NCS)(3) and CsCo(NCS)(3) showing weak ferromagnetic ordering and CsMn(NCS)(3) exhibiting antiferromagnetic ordering. Neutron diffraction data confirm non-collinear magnetic structures in CsNi(NCS)(3) and CsMn(NCS)(3). These results highlight the potential of molecular frameworks for realizing spin textures required for the next generation of information technology.