Discovery of a Dysprosium Metallocene Single-Molecule Magnet with Two High-Temperature Orbach Processes

Fu-Sheng Guo; Mian He; Guo-Zhang Huang; Sean R Giblin; David Billington; Frank W Heinemann; Ming-Liang Tong; Akseli Mansikkamäki; Richard A Layfield

doi:10.1021/acs.inorgchem.1c03980

Discovery of a Dysprosium Metallocene Single-Molecule Magnet with Two High-Temperature Orbach Processes

Inorg Chem. 2022 Apr 25;61(16):6017-6025. doi: 10.1021/acs.inorgchem.1c03980. Epub 2022 Apr 14.

Authors

Fu-Sheng Guo¹, Mian He¹, Guo-Zhang Huang², Sean R Giblin³, David Billington³, Frank W Heinemann⁴, Ming-Liang Tong², Akseli Mansikkamäki⁵, Richard A Layfield¹

Affiliations

¹ Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QR, U.K.
² Key Laboratory of Bioinorganic and Synthetic Chemistry of the Ministry of Education, School of Chemistry, Sun-Yat Sen University, Guangzhou 510006, P. R. China.
³ School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, U.K.
⁴ Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nürnberg, Egerlandstrabe 1, 91058 Erlangen, Germany.
⁵ NMR Research Group, University of Oulu, P.O. Box 8000, Oulu FI-90014, Finland.

Abstract

Magnetic bistability in single-molecule magnets (SMMs) is a potential basis for new types of nanoscale information storage material. The standard model for thermally activated relaxation of the magnetization in SMMs is based on the occurrence of a single Orbach process. Here, we show that incorporating a phosphorus atom into the framework of the dysprosium metallocene [(Cp^iPr5)Dy(Cp^PEt4)]⁺[B(C₆F₅)₄]^- (Cp^iPr5 is penta-isopropylcyclopentadienyl, Cp^PEt4 is tetraethylphospholyl) leads to the occurrence of two distinct high-temperature Orbach processes, with energy barriers of 1410(10) and 747(7) cm^-1, respectively. These barriers provide experimental evidence for two different spin-phonon coupling regimes, which we explain with the aid of ab initio calculations. The strong and highly axial crystal field in this SMM also allows magnetic hysteresis to be observed up to 70 K, using a scan rate of 25 Oe s^-1. In characterizing this SMM, we show that a conventional Debye model and consideration of rotational contributions to the spin-phonon interaction are insufficient to explain the observed phenomena.