Modification of magnetic order in Mn5Si3 and Mn5Ge3 by C ion implantation

Antiferromagnetically ordered Mn5Si3 can be driven ferromagnetic by incorporation of carbon into the voids of Mn octahedra of the hexagonal structure. While for Mn5Si3Cx polycrystals the Curie temperature saturates for x > 0.22 at TC = 152 K [1], sputtered Mn5Si3C0.8 films exhibit a TC above room temperature [2]. An enhancement of TC is also found after C doping of the isostructural compound Mn5Ge3 which is currently in the focus of possible spintronic applications. In an alternative approach, Mn5Si3Cx and Mn5Ge3Cx films were prepared by implantation of 45 - 195 keV C+ ions into Mn5Si3 or Mn5Ge3 films at elevated temperatures. The carbon-implanted samples exhibit magnetic properties very similar to their respective magnetron-sputtered counterparts as inferred from magnetization and resistivity measurements.