Hilbert Space in Isotopologue Dy(III) SMM Dimers: Dipole Interaction Limit in [^163/164Dy₂(tmhd)₆(tape)]⁰ Complexes

Abstract

Single-molecule magnets are molecular complexes proposed to be useful for information storage and quantum information processing applications. In the quest for multilevel systems that can act as Qudits, two dysprosium-based isotopologues were synthesized and characterized. The isotopologues are [ 164 Dy 2 (tmhd) 6 (tape)] (1 (I=0) ) and [ 163 Dy 2 (tmhd) 6 (tape)] (2 (I=5/2) ), where tmhd = 2,2,6,6-tetramethylheptandionate and tape = 1,6,7,12-tetraazaperylene. Both complexes showed slow relaxation at a zero applied magnetic field with dominant Orbach and Raman relaxation mechanisms. μSQUID studies at milli-Kelvin temperatures reveal quasi-single ion loops, in contrast with the expected S-shape (near zero field) butterfly loops, characteristic of antiferromagnetically coupled dimeric complexes. Through analysis of the low-temperature data, we find that the interaction operating between Dy(III) is small, leading to a small exchange biasing from the zero-field transition. The resulting indirectly coupled nuclear states are degenerate or possess a small energy difference between them. We, therefore, conclude that for the creation of Qudits with enlarged Hilbert spaces, shorter Dy(III)•••Dy(III) distances are deemed essential.

Supermolecular Aggregates of Mononuclear and Asymmetric Dinuclear Dysprosium Single-Molecule Magnets Assembled by Intermolecular Hydrogen Bonds

“…The data can be well fitted by a generalized Debye model, which gave distribution coefficient (α) values ranging from 0.08 to 0.46 (Table S3). Resultant ln(τ) vs T –1 data was fitted in the whole temperature range according to eq : , τ − 1 = τ 0 − 1 0.25em exp ( − U eff / k normalB T ) + C T n + τ QTM − 1 where the contributions of Orbach (τ 0 –1 exp( U eff / k B T )) and Raman ( CT n ) were taken into account but that of the QTM (τ QTM –1 ) relaxation process was ignored. The fitting gave parameters as following: U eff = 67(2) K, τ 0 = 1.77(24) × 10 –6 s, C = 1.44(7) K – n s –1 , and n = 3.25(5).…”

Structures and Single-Molecule Magnet Behavior of Dy3 and Dy4 Clusters Constructed by Different Dysprosium(III) Salts

“…2 was centrosymmetric, and Dy III ions had two different coordination configurations. Two Dy III ions had a nine coordination structure, with Dy1 being completed by the coordination of 45,46 At 2−25 K, the χ M T for 1 and 2 rapidly decreased until they were reduced to the lowest values of 22.47 and 33.59 cm 3 •K• mol −1 , respectively. The rapid decrease in the low-temperature region might be attributed to the presence of intermolecular antiferromagnetic interactions or dipole interactions.…”

Effect of coordinated anions on ferromagnetically coupled Dy2 zero-field single-molecule magnets

“…2,15–19 The higher the number of lanthanide ions, the less likely it is to have the same axis orientation; therefore, the SMMs containing only two lanthanide( iii ) ions are attracting more and more attention. 20–42 If a lanthanide( iii ) dinuclear SMM exhibits ferromagnetic interaction, the magnetic axis orientation of the two lanthanide( iii ) ions can be consistent, but this is a great challenging task; the reason is that the 4f electrons of different lanthanide( iii ) ions are not prone to magnetic exchange; even when the magnetic exchange occurs, it is usually a weak antiferromagnetic coupling. Notably, the ferromagnetic coupling between cations in lanthanide( iii ) SMMs may suppress the quantum tunnelling effect, which facilitates the presentation of SMM behavior in the zero field.…”