Why is the Curie temperature of Co2FeSi so high?*

We have investigated the Curie temperature of Co2FeSi and Co2TiSi by using first principle calculations. The full heusler alloy Co2FeSi has large magnetic moment per f.u. 6μB and very high Curie temperature ~1100K. And the value for Tc is 380K for half-metallic ferromagnetism Co2TiSi. We Compare these two systems using models and calculations of magnon dispersions.