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4f occupancy and magnetism of rare-earth atoms adsorbed on metal substrates

Title
4f occupancy and magnetism of rare-earth atoms adsorbed on metal substrates
Authors
Singha A.Baltic R.Donati F.Wäckerlin C.Dreiser J.Persichetti L.Stepanow S.Gambardella P.Rusponi S.Brune H.
Ewha Authors
Fabio Donati
Issue Date
2017
Journal Title
Physical Review B
ISSN
2469-9950JCR Link
Citation
Physical Review B vol. 96, no. 22
Publisher
American Physical Society
Indexed
SCI; SCIE; SCOPUS WOS scopus
Document Type
Article
Abstract
We report x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements as well as multiplet calculations for Dy, Ho, Er, and Tm atoms adsorbed on Pt(111), Cu(111), Ag(100), and Ag(111). In the gas phase, all four elements are divalent and we label their 4f occupancy as 4fn. Upon surface adsorption, and depending on the substrate, the atoms either remain in that state or become trivalent with 4fn-1 configuration. The trivalent state is realized when the sum of the atomic correction energies (4f→5d promotion energy Efd+ intershell coupling energy δEc) is low and the surface binding energy is large. The latter correlates with a high substrate density of states at the Fermi level. The magnetocrystalline anisotropy of trivalent RE atoms is larger than the one of divalent RE atoms. We ascribe this to the significantly smaller covalent radius of the trivalent state compared to the divalent one for a given RE element. For a given valency of the RE atom, the anisotropy is determined by the overlap between the spd states of the RE and the d states of the surface. For all investigated systems, the magnetization curves recorded at 2.5 K show absence of hysteresis indicating that magnetic relaxation is faster than about 10 s. © 2017 American Physical Society.
DOI
10.1103/PhysRevB.96.224418
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자연과학대학 > 물리학전공 > Journal papers
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