Magnetic anisotropies of Ho(III) and Dy(III) single-molecule magnets experimentally determined via polarized neutron diffraction

Klahn, E. A., Thiel, A. M., Degn, R. B., Kibalin, I., Gukasov, A., wilson, c., Canaj, A. B., Murrie, M. and Overgaard, J. (2021) Magnetic anisotropies of Ho(III) and Dy(III) single-molecule magnets experimentally determined via polarized neutron diffraction. Dalton Transactions, 50(40), 14207. (doi: 10.1039/D1DT01959G) (PMID:34550149)

Abstract

We present the magnetic anisotropy of two isostructural pentagonal-bipyramidal complexes, [Ln(H2O)5(HMPA)2]I3.2HMPA (HMPA=hexamethylphosphoramide, Ln=Dy, Ho). Using ac magnetic susceptibility measurements, we find magnetic relaxation barriers of 600 K and 270 K for the Dy- and Ho-compounds, respectively. This difference is supported by polarized neutron diffraction (PND) measured at 5 K and 1 T which provides the first experimental evidence that the transverse elements in the magnetic anisotropy of the Ho-analogue are significant, whereas the Dy-analogue has a near-axial magnetic anisotropy with vanishing transverse contributions. The coordination geometries of the two complexes are highly similar, and we attribute the loss of strong magnetic axiality as expressed in the atomic susceptibility tensors from PND, as well as the smaller relaxation barrier in the Ho-complex compared to the Dy-complex, to the less favorable interaction of the pentagonal bipyramidal crystal field with the characteristics of the Ho(III) 4f-charge distribution.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Murrie, Professor Mark
• Authors: Klahn, E. A., Thiel, A. M., Degn, R. B., Kibalin, I., Gukasov, A., wilson, c., Canaj, A. B., Murrie, M., and Overgaard, J.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Dalton Transactions
• Publisher: Royal Society of Chemistry
• ISSN: 1477-9226
• ISSN (Online): 1477-9234
• Published Online: 02 September 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Dalton Transactions 50(40):14207
• Publisher Policy: Reproduced under a Creative Commons licence

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
172637		Putting the Squeeze on Molecule-Based Magnets	Mark Murrie	Engineering and Physical Sciences Research Council (EPSRC)	EP/N01331X/1	Chemistry