Slow magnetic relaxation in a europium(II) complex

Dylan Errulat; Katie L M Harriman; Diogo A Gálico; Elvin V Salerno; Johan van Tol; Akseli Mansikkamäki; Mathieu Rouzières; Stephen Hill; Rodolphe Clérac; Muralee Murugesu

doi:10.1038/s41467-024-46196-w

Slow magnetic relaxation in a europium(II) complex

Nat Commun. 2024 Apr 8;15(1):3010. doi: 10.1038/s41467-024-46196-w.

Authors

Affiliations

¹ Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
² National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
³ NMR Research Unit, University of Oulu, P. O. Box 3000, 90014, Oulu, Finland.
⁴ Univ. Bordeaux, CNRS, CRPP, UMR 5031, F-33600, Pessac, France.
⁵ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA. shill@magnet.fsu.edu.
⁶ Department of Physics, Florida State University, Tallahassee, FL, 32306, USA. shill@magnet.fsu.edu.
⁷ Univ. Bordeaux, CNRS, CRPP, UMR 5031, F-33600, Pessac, France. rodolphe.clerac@u-bordeaux.fr.
⁸ Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada. m.murugesu@uottawa.ca.

^# Contributed equally.

Abstract

Single-ion anisotropy is vital for the observation of Single-Molecule Magnet (SMM) properties (i.e., a slow dynamics of the magnetization) in lanthanide-based systems. In the case of europium, the occurrence of this phenomenon has been inhibited by the spin and orbital quantum numbers that give way to J = 0 in the trivalent state and the half-filled population of the 4f orbitals in the divalent state. Herein, by optimizing the local crystal field of a quasi-linear bis(silylamido) Eu^II complex, the [Eu^II(N{SiMePh₂}₂)₂] SMM is described, providing an example of a europium complex exhibiting slow relaxation of its magnetization. This behavior is dominated by a thermally activated (Orbach-like) mechanism, with an effective energy barrier of approximately 8 K, determined by bulk magnetometry and electron paramagnetic resonance. Ab initio calculations confirm second-order spin-orbit coupling effects lead to non-negligible axial magnetic anisotropy, splitting the ground state multiplet into four Kramers doublets, thereby allowing for the observation of an Orbach-like relaxation at low temperatures.