Co_(2+x)Fe_(1-x)Si/MgO(001) Heusler alloys: Influence of off-stoichiometry and lattice distortion on the magnetic properties in bulk and on MgO(001)

摘要

We investigate the influence of lattice distortion and off-stoichiometry on the electronic and magnetic properties of Co_(2+x)Fe_(1-x)Si Heusler alloys in their L2_1 bulk phase and on MgO(OOl) using the density functional theory. Our investigations show that Co excess does not significantly change the magnetic properties, whereas an increase of the Fe content can reduce the spin polarization. In addition, the influence of off-stoichiometry on x-ray absorption spectra is studied. For comparison, x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements have been carried out for Co_2FeSi/MgO(001) at the Co and Fe L_(2,3) edges.