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Abstract:
X-ray magnetic circular dichroism (XMCD) of core-level absorption (x-ray
absorption spectroscopy, XAS) spectra in the soft x-ray region has been
measured for the ferromagnetic Heusler alloy Rh2MnGe at the Rh M-3,M-2
and Mn L-3,L-2 edges. The ratio of Rh and Mn spin moments amounts to
0.05 which is smaller than the ratio of 0.1 determined by a local
density approximation electronic band structure calculation. We have
found that the orbital moments of the Rh 4d and Mn 3d states are very
small. The observed Rh 2p XAS spectrum can be understood on the basis of
the Rh 3d partial density of unoccupied states as is typical for metals.
The observed features of the Mn 2p XAS and XMCD spectra are dominated by
final state multiplets as is typical for oxides. The comparison of
experimental and ab initio calculated XAS/XMCD spectra reveals a strong
narrowing of the Mn 3d bands, indicating strongly localized Mn moments.
The magnetic moments are considerably more localized for Rh2MnGe in
comparison with the isoelectronic compound Co2MnGe. In spite of the
strong localization of the Mn moment, the temperature dependences of
sublattice magnetization are equal for the Mn and Rh sublattices in
contrast to the prediction by a Heisenberg model. This might be
attributed to the remaining itinerant character of the Rh moment.