Influence of the L21 ordering degree on the magnetic properties in Co2MnSi Heusler films

TL;DR

This study investigates how varying the L21 ordering degree in Co2MnSi Heusler films, achieved through different annealing temperatures, affects their magnetic properties, revealing complex changes in coercivity, magnetization, exchange stiffness, and anisotropy.

Contribution

It demonstrates the correlation between L21 order improvement and magnetic property modifications in Co2MnSi films, highlighting the effects of annealing temperature.

Findings

Coercivity peaks at 425°C annealing.

Saturation magnetization decreases by 9%.

Exchange stiffness increases by 8%.

Abstract

We report on the influence of the improved L21 ordering degree on the magnetic properties of Co2MnSi Heusler films. Different fractions of the L21 phase are obtained by different post-growth annealing temperatures ranging from 350 degC to 500 degC. Room temperature magneto-optical Kerr effect measurements reveal an increase of the coercivity at an intermediate annealing temperature of 425 degC, which is a fingerprint of an increased number of pinning centers at this temperature. Furthermore, Brillouin light scattering studies show that the improvement of the L21 order in the Co2MnSi films is correlated with a decrease of the saturation magnetization by about 9%. The exchange stiffness constant of Co2MnSi, however, increases by about 8% when the L21 order is improved. Moreover, we observe a drop of the cubic anisotropy constant K1 by a factor of 10 for an increasing amount of the L21 phase.