Experimental evidence of the ferrimagnetic ground state of Sr ₂ FeMoO ₆ probed by X-ray magnetic circular dichroism

Abstract

We have investigated the magnetic structure of a Sr2FeMoO6 single crystal by X-ray magnetic circular dichroism at the L2,3 edges of Fe and Mo sites. The spin magnetic moments we find on Fe (3.05µB) and Mo (−0.32µB) give, for the first time, a direct confirmation of their ferrimagnetic ordering. The presence of a finite spin moment on Mo together with only very small orbital moments on both Fe and Mo confirms that the predicted half-metallicity of the Sr2FeMoO6 compound is due to a configuration with five localized d electrons forming a high-spin moment on Fe and one s antiparallel delocalized electron shared between the Mo and the other sites.

Magnetic moments of W5dinCa2CrWO6andMajewski1, Geprägs2, Boger3 et al. 2005Phys. Rev. B

“…This double peak structure is identified as the signature of the crystal field split- ting (∼ 3.2 eV for Sr 2 CrWO 6 ) of the 5d band into t 2g and e g states. Similar double peak structures have also been observed at the Mo L 2,3 absorption edges for the double perovskite Sr 2 FeMoO 6 [8], however, with a more pronounced separation between the peaks and slightly different intensities at the L 3 edge. As shown in Fig.…”

“…For * Electronic address: Petra.Majewski@wmi.badw.de † Electronic address: alff@oxide.tu-darmstadt.de Sr 2 FeMoO 6 , recent XMCD measurements showed a spin moment of about 3 µ B for Fe 3+ ion at the B site. Interestingly, for the non-magnetic Mo 5+ ion at the B ′ site an antiparallel aligned spin moment of about −0.3 µ B and a small orbital contribution was found [8]. This observation is in agreement with a generalized double exchange or kinetic energy driven exchange model proposed by Sarma et al [9] to explain the strong ferromagnetic exchange in double perovskites despite the large distance between the magnetic ions (e. g. 8.82Å for Sr 2 CrWO 6 ).…”

“…For completeness, we include also data previously published by other groups on similar compounds [7,8,21]. Furthermore, the ratio | m L /m S | is calculated, since this quantity is not affected by possible uncertainties in the calculated number of holes.…”

NMR Study of (Sr,Ba,La)2Fe1+yMo1-yO6Double Perovskites

“…The Fe-Mo double perovskites exhibit relatively high magnetic ordering temperatures. Neutron diffraction, X-ray magnetic circular dichroism (XMCD) and nuclear magnetic resonance (NMR) measurements have proven the existence of a non-integer magnetic moment at Mo and Fe sites ( [2,3] and [4]). La substitution was found to increase the Curie temperature and also the number of defects ( [5,6] and [7]).…”

Crystal structural, magnetic, and electrical transport properties of Sr1.1K0.9FeMoO6 double perovskite

“…In the ideal SFMO structure, the Sr(FeMo)O 3 perovskite building blocks form a NaCl superlattice in such a way that the Fe-Fe (Mo-Mo) distance is doubled with respect to the elementary perovskite unit cell. The magnetic structure of this oxide was originally [1] described as resulting from an antiferromagnetic coupling between Fe-d 5 and Mo-4d 1 electrons, in a ferrimagnetic-like structure. However, recent reports indicating that the dominant magnetic interaction in the system is ferromagnetic [2,3] and that the magnetic moment of Mo ions is small [4,5] have forced a review of the picture.…”