The x-ray magnetic circular dichroism spin sum rule for 3d⁴systems: Mn³⁺ions in colossal magnetoresistance manganites

Abstract

The colossal magnetoresistance manganites La(0.87±0.02)Sr(0.12±0.02)MnO(3+δ), La(0.78±0.02)Sr(0.17±0.02)MnO(3+δ), and La(0.66±0.02)Sr(0.36±0.02)MnO(3+δ) (δ close to 0) were investigated by using soft x-ray magnetic circular dichroism (XMCD) and magnetometry. Very good agreement between the values for the average Mn magnetic moments determined with these two methods was achieved by correcting the XMCD spin sum rule results by means of charge transfer multiplet calculations, which also suggest a charge transfer of ~50% for Mn(4+) and approximately equal to 30% for Mn(3+). The magnetic moment was found to be localized at the Mn ions for x = 0.17 and 0.36 at 80 K and for x = 0.12 in the temperature range from 80 to 300 K. We discuss our findings in the light of previously published data, confirming the validity of our approach.

Probing the magnetic moments of [MnIII6CrIII]3+ single-molecule magnets—A cross comparison of XMCD and spin-resolved electron spectroscopy

“…Despite the reasonably good agreement of the spin magnetic moment derived via the sum rule approach from XMCD and SPES data, the obtained results are significantly lower than the theoretical value expected for the Mn III and Cr III coupling scheme and previous data from AC and DC magnetometry [26], indicating the physical limitations of the sum rule formalism for 3d 4 systems as described by various authors [43][44][45][46][47][48][49][50].…”

“…Especially in the case of 3d transition metals, corrections to the sum rule results are required, either by applying correction factors (Teramura et al [48]) or by comparing the XMCD data to the results from multiplet calculations as shown by Piamonteze et al [49]. The latter method has been applied successfully to Mn III systems by Kuepper et al [50].…”

“…However, these constraints apply to both experimental methods, therefore the sum rule approach remains a useful tool for the comparison between XMCD and spin-resolved electron spectroscopy data. Charge-transfer multiplet calculations as described in references [49,50] are required to derive absolute values for the local magnetic moments without the limited accuracy of the sum rule formalism.…”

“…The correction factor successfully derived for Mn III ions by Kuepper et al [50] was used, although it has to be considered that the Mn III ions in [Mn III 6 Cr III ](ClO 4 ) 3 are embedded in a different chemical environment.…”

Intra- and interparticle magnetism of cobalt-doped iron-oxide nanoparticles encapsulated in a synthetic ferritin cage

“…This was observed for spectra that were collected by reversing the incident photon helicity, and by reversing the polarity of the applied field, indicating that the effect was not due to an artifact of the experimental conditions. Since the d-orbitals are very localized and should not contribute significantly to the XMCD spectrum past the L 2 edge, the persisting XMCD intensity may be due to the excitation of polarized, delocalized s-electrons 24,25 . Since s-states are not relevant to the calculation of m l /m s , the integral was terminated at the point where there was no longer a slope in the XMCD intensity (799 eV).…”