Incident photon energy dependence of the resonant x-ray magnetic scattering cross section of a samarium film

Abstract

Resonant x-ray magnetic scattering is widely used as an element selective probe of magnetism in solids. The present work deals with a different, less frequently addressed aspect: the electronic shell selectivity. Due to the complexity of the atomic effects inherent to the resonant process and at the origin of the electronic shell selectivity, the data are generally considered on a qualitative basis. Here, we try to extend the arguments to a semiquantitative level. We show, through a detailed spectroscopic study of the resonance at the L 2 and L 3 edges of samarium in a single-crystal epitaxial film, how the exploitation of the atomic effects can lead to a deeper understanding of long-range magnetic order in this material. At the L 2,3 edges of rare earths, dipole resonances carry information on the polarization of the 5d band, whereas quadrupole resonances reflect the polarization of the 4 f shell. The narrow width of the 4 f band permits the interpretation of the quadrupole resonance below the L 3 edge using atomic considerations. A systematic study of the dependence of the 4 f quadrupole resonance on wave-vector transfer shows that, within our resolution, the magnitude of the 4 f moments in samarium is independent of the local environment ͑cubic or hexagonal͒. On the other hand, the energy dependence of the dipole resonance at and above the L 2 and L 3 absorption edges shows two maxima and is interpreted in the framework of an extended density of 5d states. Finally, the relative temperature dependences of the dipole and quadrupole resonances sheds light upon the respective contributions of the 4 f and 5d levels to the long-range magnetic order in samarium.

Resonant x-ray scattering from multi-kmagnetic structures

“…͑1͒ in the local ionic approximation according to the treatment of Hill and McMorrow, 18 on the assumption that the underlying symmetries will carry over to the metallic state, 24,25 and write…”

Spectral line shapes of UM2- and AsK-edge resonant x-ray scattering in the two antiferromagnetic phases of UAs

“…Neutron diffraction studies have determined a small change in the ordered magnetic moment from the type-I to the type-IA phase, 7 from 1.9 B to 2.2 B , and, therefore, the understanding is that there is not a significant change in the polarization associated with the 6d band between these phases. On this basis, as well as on that of previous RXS studies of rare-earth [10][11][12][13][14][15][16] and actinide 17 systems, it may not be expected that the E1 RXS contribution to the U M 2 line shape changes significantly between the two phases. However, if this contribution were to change or an E1 contribution appeared in only one of the phases, then this could be taken as an indication of a change in the 6d-5f hybridization.…”

p–f mixing in CeSb, studied by resonant X-ray scattering

“…Strong resonances of similar line shape are observed at both positions in the s-p channel, with a maximum 2.5 eV above the edge. The position relatively to the absorption edge shows that this resonance is mainly dipole (2p-5d) [5]. The intensity reaches 11 000 counts/s at the (0 4/7 4) reflection, and is about 10 times weaker at the (0 2/7 4), which mainly reflects the ratio of the magnetic structure factors.…”