Local structural and magnetic properties of Mn₅Si₃Cₓ films

Metallic Mn5Si3Cx (x≈1) films prepared by magnetron sputtering exhibit fairly high magnetic ordering temperatures above room temperature in contrast to the antiferromagnetic Mn5Si3 (TN=100 K). X-ray absorption spectroscopy indicates a change of the local atomic arrangement around the two different Mn sites (MnI and MnII) by the incorporation of carbon into the hexagonal lattice compared to Mn5Si3. The two inequivalent Mn sites give rise to different local magnetic moments of Mn as determined by broad-band \{NMR\} and confirmed by bandstructure calculations. Moreover, the calculations corroborate the stabilization of ferromagnetic order by the incorporation of carbon.