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High‐Frequency EPR Spectra of [Fe 8 O 2 (OH) 12 (tacn) 6 ]Br 8 : A Critical Appraisal of the Barrier for the Reorientation of the Magnetization in Single‐Molecule Magnets
Author(s) -
Barra Anne Laure,
Gatteschi Dante,
Sessoli Roberta
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/(sici)1521-3765(20000502)6:9<1608::aid-chem1608>3.0.co;2-8
Subject(s) - anisotropy , spectral line , electron paramagnetic resonance , magnetic anisotropy , magnetization , condensed matter physics , crystallite , cluster (spacecraft) , dipole , ion , single crystal , chemistry , nuclear magnetic resonance , materials science , magnetic field , physics , crystallography , optics , programming language , organic chemistry , quantum mechanics , astronomy , computer science
A detailed multifrequency high‐field‐high‐frequency EPR (95‐285 GHz) study has been performed on the single‐molecule magnet of formula [Fe 8 O 2 (OH) 12 (tacn) 6 ]Br 8 ⋅9 H 2 O, in which tacn=1,4,7‐triazacyclononane. Polycrystalline powder spectra have allowed the estimation of the zero‐field splitting parameters up to fourth order terms. The single‐crystal spectra have provided the principal directions of the magnetic anisotropy of the cluster. These results have been compared with an evaluation of the intra‐cluster dipolar contribution to the magnetic anisotropy; this suggests that single‐ion anisotropy is the main contributor to the magnetic anisotropy. The role of the transverse magnetic anisotropy in determining the height of the barrier for the reversal of the magnetization is also discussed.