Search of novelty Mn-based Heusler alloys with high half-metallicity and high phase stability

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Phase stability and magnetic properties of half-metallic Mn-based Heusler alloys were investigated. It is confirmed that the highly ordered L21 phase can is obtained by appropriate heat treatments for controlling the degree of order and microstructure. In this case, the magnetic moment of the Mn2VAl well accords with the theoretical value of 2 mB/f.u., suggesting that the electronic state shows half-metallicity. Value of the spin-stiffness constant from the magnetization measurements of the Mn2VAl is about 5.5 meV-(nm)2, and it is about twice as large as that of the Co-based Heusler alloys having similar values of the Curie temperature. This means that the magnetic state of Mn2VAl is significantly stable. In addition, single crystal of the Mn2VAl was grown for photoelectron spectroscopy measurements. It is also confirmed that single phase of the L21-type Mn2VGa and Mn2CoGa alloys can be obtained.