Spin Stiffness Constant of Half-metallic Ferrimagnet in Mn-based Heusler Alloys

Abstract

In order to investigate the spin stiffness constant, D, of Mn-based Heusler alloys with half-metallic density of states, magnetic measurements were properly carried out. The Curie temperature, TC, of Mn2VAl, Mn50V20Al30 and Mn2CoGa were 768, 738 and 740K, respectively. The value of D was evaluated from the temperature, T, dependence of the spontaneous magnetization in each specimen below 150K, where linear dependence of T3/2 was observed. The D values for these materials were obtained to be 5.34, 4.38 and 5.67 meV·(nm)2 and significantly larger than that for Co-based Heusler alloys reported previously. The strong exchange interaction would be the reason that the Mn-based Heusler alloys indicate high TC even though they have not so large total magnetic moment comparing to that of Co-based Heusler alloys.