ThCr 2 Si 2 C: An Antiferromagnetic Metal with a Cr 2 C Square Lattice.

A quaternary compound, ThCr 2 Si 2 C, was synthesized by using the arc-melting technique. The compound adopts a tetragonal CeCr 2 Si 2 C-type crystal structure. The electronic resistivity and specific heat data exhibit metallic behavior, while the magnetic susceptibility displays a pronounced broad peak at around 370 K, indicating the antiferromagnetic phase transition. The first-principles calculations suggest A-type antiferromagnetic ordering of the Cr sublattice, which is confirmed by neutron diffraction experiments. By comparing the crystal structure of ThCr 2 Si 2 C with the isostructural Cr-based compounds, the magnetic state of Cr 3d orbital is discussed in terms of the band-filling effects and indirect spin exchange interaction.