Resonant [formula omitted] X-ray emission and [formula omitted] X-ray absorption spectra of 3d metals in Co 2MnZ ( [formula omitted], Ga, Sn, Sb) Heusler alloys as an element-selective probe of spin character of valence band

Abstract

The 3d metal L α , β resonant X-ray emission spectra (RXES) and L 3 , 2 X-ray absorption spectra (XAS) of the Co 2MnZ ( Z = Al , Ga, Sn, Sb) alloys were measured using linearly polarized soft X-rays. The Mn L α and Co L α spectra are compared with results of spin-polarized calculations of Mn 3d and Co 3d partial densities of states performed for each alloy. It is found that a satellite observed at the high-energy side of Mn L α spectra is due to the localized Mn 3d states located above the Fermi energy. It is shown that the presence of the same satellite structure indicates a higher degree of spin-polarization of Mn 3d states than Co 3d states. Both the intensity of the satellite structure in Mn L α spectra and the L β / L α , peak ratio are increased and follow the atomic number of Z element. The effect is especially strong when excitating slightly above the L 3 and L 2 threshold energies as well as at resonance. We observe a correlation between these spectral parameters and the magnitude of local magnetic moment. The changes occurring in the Mn L α , β RXES are in good agreement with a predicted decrease in p–d hybridization (between the atoms of Z element and Mn atoms). The calculated local density of Mn 3d states at the Fermi energy follows the same trend as the hybridization. This suggests that L α , β RXES of 3d metals can be used to monitor the degree of spin-polarization of the valence band states and the local density of states at the Fermi level. Note that neither the Mn L 2 , 3 absorption nor the Co L 2 , 3 and Co L α , β emission spectra of the alloys are affected by the different composition (different Z elements).