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Dresden 2017 – scientific programme

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MA: Fachverband Magnetismus

MA 35: Magnetic Particles / Clusters

MA 35.8: Talk

Wednesday, March 22, 2017, 11:15–11:30, HSZ 101

Changing the magnetism of eightfold coordinated 3d transition metal ions in polyoxopalladates by hydrogen plasmaNataliya Svechkina1, Natalya V. Izarova1, Detlef Schmitz2, Alevtina Smekhova1, and •Carolin Schmitz-Antoniak11FZ Jülich (PGI-6) — 2HZB, Berlin

Cuboid-shaped polyoxopalladates hosting either Fe3+ (3d5) or Co2+ (3d7) ions in their centres have been studied by means of x-ray absorption spectroscopy at the L3,2 absorption edges of the 3d elements. While the x-ray absorption near-edge structure (XANES) contains already important information on the valence state, the x-ray magnetic linear dichroism (XMLD) and x-ray magnetic circular dichroism (XMCD) were used to refine the quantification of the crystal field related to the eight oxygen ions surrounding the central ion by comparison with simulations using the CTM4XAS program. In addition, spin and orbital magnetic moments were derived by a sum-rule based analysis of the XMCD.

After a hydrogen plasma treatment, the Fe ions were reduced from the 3d5 to a 3d6 state while the Co 3d7 state remains unaffected. However in both cases, drastic changes of the crystal field and the magnetic properties were obtained pointing to a possible application in nanoscale hydrogen sensing or storage devices.

In addition, data of re-oxidised samples are presented and the influence of different heterogroups stabilising the polyoxopalladates is discussed.

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