XAS et XMCD aux seuils L₂₃ de Fe et Mo dans Sr₂

Electronic structure and x-ray magnetic circular dichroism of Sr₂FeMoO₆ : Ab initio calculations
Kanchana V, Vaitheeswaran G, Alouani M, Delin A
Phys. Rev. B 75, 220404 (2007)

Theoretical investigations of the electronic structure (see Fig. 1), x-ray absorption (XAS), and x-ray magnetic circular dichroism (XMCD) at the Fe L_2,3 and Mo L_2,3 edges of Sr₂FeMoO₆ are carried out by means of the generalized gradient approximation. The magnetic coupling between Fe and Mo is found to be antiparallel, which gives direct confirmation of ferrimagnetic ordering and settles controversies existing between the earlier experimental reports.This is also confirmed by our good agreement of the Mo L_2,3 edges with experiment (see Fig. 2). Using our theoretical spectra, we recalculate the spin and orbital magnetic moments by means of the XMCD sum rules and compare the results with the direct self-consistent calculation and experiment.

Fig. 1 : Calculated spin-resolved partial density of states (DOS) of Sr₂FeMoO₆ at the experimental lattice constants in units of states/eV/fu (formula unit). The partial DOS of 3d-Fe are blue (continuous line), that of 4d-Mo red (dashed lines), and that of 2p-O green (dotted lines). The majority spins are represented in the positive scale part of the plot, and that of minority spins in the negative part. The DOS shows that Sr₂FeMoO₆ is a ferromagnetic half-metal.

Fig. 2 : Calculated XAS and XMCD spectra of Mo L₂ L₃ edges (full lines) as compared to the experimental results (dashed lines). We have used a FWHM of 0.5 eV to broaden the spectra.

Involved persons :

M. Alouani

In collaboration with :

V. Kanchana, G. Vaitheeeswaren, A. Delin, Department of Materials Science and Engineering, Royal Institute of Technology, 10044 Stockholm, Sweden