Data used in the paper "Magnetic order and Li-diffusion in the 1/3-filled Kagome layers of antiperovskite Lithium-ion battery materials (Li2Fe)SO and (Li2Fe)SeO"

The recently discovered lithium-rich antiperovskites (Li2Fe)SeO and (Li2Fe)SO host lithium and iron ions on the same atomic position which octahedrally coordinates to central oxygens. In a cubic antiperovskite these sites form Kagome planes stacked along the 111 > directions which triangular motifs induce high geometric frustration in the diluted magnetic sublattice for antiferromagnetic interactions. Despite their compelling properties as high-capacity Li-ion battery cathode materials, very little is known about the electronic and magnetic properties of lithium-rich antiperovskites. We report static magnetization, Mössbauer, and NMR studies on both compounds. Our data reveal a Pauli paramagnetic-like behaviour, a long-range antiferromagnetically ordered ground state below ≈ 50 K and a regime of short-range magnetic correlations up to 100 K. Our results are consistent with a random Li-Fe distribution on the shared lattice position. In addition, Li-hopping is observed above 200 K with an activation energy of Ea = 0.47 eV. Overall, our data elucidate static magnetism in a disordered magnetically frustrated and presumably semimetallic system with thermally induced ion diffusion dynamics.