Itinerant and localized magnetic moments in ferrimagnetic Mn_2 CoGa thin films probed by x-ray magnetic linear dichroism: Experiment and ab initio theory

摘要

Epitaxial thin films of the half-metallic X_a compound Mn_2CoGa (Hg_2CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality films with a bulk magnetization of 1.95(5)μb per unit cell were obtained. The L_(2.3) x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory (DFT) and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism, in good agreement with theory as well, allows us to distinguish between itinerant and local Mn moments. Based on noncollinear spin DFT, it is shown that one of the two Mn moments has local character, whereas the other Mn moment and the Co moment are itinerant.