科研之友
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摘要
The magnetic properties and electronic structure of Mn2NiSi and Ni2MnSi Heusler alloys have been studied by using the first-principles. The possible non-modulated martensitic transformations in Mn2NiSi and Ni2MnSi alloys have been investigated. In both austenitic and martensitic phases, Mn2NiSi is a ferrimagnet. The antiparallel alignment of Mn(A) and Mn(B) moments is found. In martensitic Mn2NiSi, the global energy minimum occurs at c/alpha = 1.37 with 1% decrease of the martensitic cell volume. The energy difference. triangle E between the austenitic and martensitic phases is 400 meV/cell, so it is more likely to realize martensitic transformation for Mn2NiSi alloy. Unlike Mn2NiSi alloy, the global energy minimum occurs at c/alpha = 1.02 without cell volume change in martensitic Ni2MnSi. But the energy difference. triangle E between the austenitic and martensitic phases is only 0.3meV/cell. Meanwhile, around c/alpha = 1 an anomaly is observed in the E-tot-c/alpha curve which is related to a very slightly martensitic distortion trend in Ni2MnSi.
