Effect of low-valent atom substitution on electronic structure and magnetic properties of Fe 1.5M 0.5CoSi (M=V, Cr, Mn, Fe) Heusler alloys

Abstract

Quaternary Heusler alloys Fe 1.5M 0.5CoSi with M=V, Cr, Mn and Fe have been investigated theoretically and experimentally. All of these samples crystallize in the ordered Heusler-type structure. The calculated electronic structure shows a pseudogap around E F in the minority spin states of Fe 2CoSi. With the substitution of low-valent atoms for Fe, the majority antibonding peak is shifted to higher energy and a minority gap around the Fermi level is opened. High spin polarization ratio is obtained in Fe 1.5M 0.5CoSi (M=V, Cr, Mn) alloys. The calculated total spin moments decrease with decreasing number of valence electrons and follow the Slater–Pauling curve, which agree with the experimental results well. The Curie temperature decreases as M atom varies from Fe to V, but is always higher than 650 K, which is suitable for technical applications.