Influence of the L21 ordering degree on the magnetic properties of Co2 MnSi Heusler films

Abstract

We report on the influence of the improved L21 ordering degree on the magnetic properties of Co2 MnSi Heusler films. Different fractions of the L21 phase are obtained by different postgrowth annealing temperatures ranging from 350 °C to 500 °C. Room temperature magneto-optical Kerr effect measurements reveal an increase of the coercivity at an intermediate annealing temperature of 425 °C. This is probably a result of an increasing number of pinning centers on the one hand and a drop of the cubic anisotropy constant K1 by a factor of 10 on the other for an increasing amount of the L21 phase. Furthermore, Brillouin light scattering studies show that the improvement of the L21 order in the Co 2 MnSi films is correlated with a decrease of the saturation magnetization by about 7%. The exchange stiffness constant of Co2 MnSi, however, increases by about 8% when the L21 order is improved. © 2008 American Institute of Physics.