Relationship between the magnetic moment of Lu and the magnetic behavior of (Y_y,Lu_(1-y))(Co_(1-x)Al_x)_2 from x-ray absorption spectroscopy and x-ray magnetic circular dichroism

摘要

We present an x-ray magnetic circular dichroism (XMCD) study performed at both the Co K edge and the Lu L_(2,3) edges on (Y_y,Lu_(1-y))(Co_(1-x)Al_x)_2 systems. The XMCD spectra reflect the different magnetic character of these systems, allowing us to monitor the transition from weak to strong ferromagnetism. The XMCD at the Lu L_(2,3) edges indicates the existence of an ordered 5d moment at the lutetium sites that is coupled antiparallel to the Co moment. Estimates of the magnetic moment of Lu have been obtained by applying the XMCD sum rules. Our results show that there is a correlation between the Lu 5d-induced magnetic moment and the magnetic character of the (Y_y,Lu_(1-y))(Co_(1-x)Al_x)_2 compounds. These results suggest that the developing of the Lu moment plays an important role in reinforcing the magnetic interactions and favoring the ferromagnetic character of the Lu-rich compounds.