The incorporation of carbon into the antiferromagnetic Mn5Si3 compound gives rise to ferromagnetic order.
Mn5Si3Cx films prepared by simultaneous sputtering of elemental Mn, Si, and C at elevated substrate temperatures have a Curie temperature of TC= 350 K for an optimum doping level x = 0.8 inferred from magnetization measurements [C. Sürgers et al., Phys. Rev. B 68, 174423 (2003)]. The microscopic origin of the C-induced ferromagnetism still needs to be explored. We report on the electronic transport properties of 100-nm thick Mn5Si3Cx films (0 < x < 1.2) prepared by magnetron sputtering in high vacuum. All films show a metallic behavior of the temperature (T) dependent resistance R. However, R(T), the magnetoresistance, and the Hall effect of Mn5Si3 films strongly change by C doping in agreement with the change of magnetic order from antiferromagnetic to ferromagnetic. Furthermore, for films with the optimum doping level x = 0.8 we observe the lowest residual resistivity of all C-doped films, suggesting that for this composition all voids of the Mn octahedra are filled with C, whereas overdoping leads to an enhanced residual resisistivity even larger than of Mn5Si3. |