Magnetic Anisotropy Trends along a Full 4f-Series: The fn+7 Effect

Briganti, Matteo; Lucaccini, Eva; Chelazzi, L.; Ciattini, Samuele; Sorace, Lorenzo; Sessoli, Roberta; Totti, Federico; Perfetti, Mauro

doi:10.1021/jacs.1c02502

Cited by 58 publications

(63 citation statements)

References 55 publications

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“…Despite the lack of symmetry, the computed g-tensor of the ground KD is quite axial, see Table S6, as is commonly found for Dy 3+ complexes despite the low symmetry coordination geometries, as recently explained. [45] The direction of the easy axis (see Fig. 1) is almost parallel to the bond with the closest oxygen atom of one acac − ligand, as commonly found [46,47].…”

Section: The Dy 3+ Crystal Field: Static Ab Initio Calculations and V...supporting

confidence: 57%

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

Briganti,

Santanni,

Tesi

et al. 2021

Preprint

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The unique electronic and magnetic properties of Lanthanides molecular complexes place them at the forefront of the race towards high-temperature single-ion magnets and magnetic quantum bits. The design of compounds of this class has so far been almost exclusively driven by static crystal field considerations, with emphasis on increasing the magnetic anisotropy barrier. This guideline has now reached its maximum potential and new progress can only come from a deeper understanding of spin-phonon relaxation mechanisms. In this work we compute relaxation times fully ab initio and unveil the nature of all spin-phonon relaxation mechanisms, namely Orbach and Raman pathways, in a prototypical Dy single-ion magnet. Computational predictions are in agreement with the experimental determination of spin relaxation time and crystal field anisotropy, and show that Raman relaxation, dominating at low temperature, is triggered by low-energy phonons and little affected by further engineering of crystal field axiality. A comprehensive analysis of spin-phonon coupling mechanism reveals that molecular vibrations beyond the ion's first coordination shell can also assume a prominent role in spin relaxation through an electrostatic polarization effect. Therefore, this work shows the way forward in the field by delivering a novel and complete set of chemically-sound design rules tackling every aspect of spin relaxation at any temperature.

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Section: The Dy 3+ Crystal Field: Static Ab Initio Calculations and V...supporting

confidence: 57%

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

Briganti,

Santanni,

Tesi

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Despite the lack of symmetry, the computed g -tensor of the ground KD is quite axial ( g X = 0.045, g Y = 0.089, g Z = 19.371, see Table S6), a common feature for Dy 3+ complexes despite the low symmetry coordination geometries, as recently pointed out and rationalized . The direction of the easy axis (see Figure ) is almost parallel to the bond with the closest oxygen atom of one acac – ligand, as commonly found. , Such a direction can be rationalized in the following way: in order to minimize the electrostatic repulsion with the ligands, the oblate electron density of the ground m J = ± 15/2 doublet is mostly localized in the plane defined by the two water molecules’ oxygens (neutral), which also present the longest bond lengths (see Figure ).…”

Section: Resultsmentioning

confidence: 59%

A Complete Ab Initio View of Orbach and Raman Spin–Lattice Relaxation in a Dysprosium Coordination Compound

et al. 2021

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The unique electronic and magnetic properties of lanthanide molecular complexes place them at the forefront of the race toward high-temperature single-molecule magnets and magnetic quantum bits. The design of compounds of this class has so far being almost exclusively driven by static crystal field considerations, with an emphasis on increasing the magnetic anisotropy barrier. Now that this guideline has reached its maximum potential, a deeper understanding of spin-phonon relaxation mechanisms presents itself as key in order to drive synthetic chemistry beyond simple intuition. In this work, we compute relaxation times fully ab initio and unveil the nature of all spin-phonon relaxation mechanisms, namely Orbach and Raman pathways, in a prototypical Dy single-molecule magnet. Computational predictions are in agreement with the experimental determination of spin relaxation time and crystal field anisotropy, and show that Raman relaxation, dominating at low temperature, is triggered by low-energy phonons and little affected by further engineering of crystal field axiality. A comprehensive analysis of spin-phonon coupling mechanism reveals that molecular vibrations beyond the ion’s first coordination shell can also assume a prominent role in spin relaxation through an electrostatic polarization effect. Therefore, this work shows the way forward in the field by delivering a novel and complete set of chemically sound design rules tackling every aspect of spin relaxation at any temperature.

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“…However, they are far from being perfect and use of the results obtained by this method requires a preliminary benchmarking against a set of accurately determined properties . This approach is gaining increasing momentum in the literature: the calculated properties include low-temperature luminescence, , EPR spectroscopy, ,, single-crystal magnetometry, ,− inelastic neutron scattering, , and advanced spectroscopic techniques. − With this aim, ab initio calculations were performed on 1 and 2 , and the results are compared with EPR and CTM data. This provides a sound basis for the following discussion on the magnetic properties of these systems.…”

Section: Resultsmentioning

confidence: 99%

Single-Ion Anisotropy and Intramolecular Interactions in Ce^III and Nd^III Dimers

et al. 2021

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This article reports the syntheses, characterization, structural description, together with magnetic and spectroscopic properties of two isostructural molecular magnets based on the chiral ligand N , N ′- bis ((1,2-diphenyl-(pyridine-2-yl)methylene)-( R , R / S , S )-ethane-1,2-diamine), L1 , of general formula [Ln 2 ( RR - L1 ) 2 (Cl 6 )] · MeOH · 1.5H 2 O, (Ln = Ce ( 1 ) or Nd ( 2 )). Multifrequency electron paramagnetic resonance (EPR), cantilever torque magnetometry (CTM) measurements, and ab initio calculations allowed us to determine single-ion magnetic anisotropy and intramolecular magnetic interactions in both compounds, evidencing a more important role of the anisotropic exchange for the Nd III derivative. The comparison of experimental and theoretical data indicates that, in the case of largely rhombic lanthanide ions, ab initio calculations can fail in determining the orientation of the weakest components, while being reliable in determining their principal values. However, they remain of paramount importance to set the analysis of EPR and CTM on sound basis, thus obtaining a very precise picture of the magnetic interactions in these systems. Finally, the electronic structure of the two complexes, as obtained by this approach, is consistent with the absence of zero-field slow relaxation observed in ac susceptibility.

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Magnetic Anisotropy Trends along a Full 4f-Series: The fⁿ⁺⁷ Effect

Cited by 58 publications

References 55 publications

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

A Complete Ab Initio View of Orbach and Raman Spin–Lattice Relaxation in a Dysprosium Coordination Compound

Single-Ion Anisotropy and Intramolecular Interactions in Ce^III and Nd^III Dimers

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Magnetic Anisotropy Trends along a Full 4f-Series: The fn+7 Effect

Cited by 58 publications

References 55 publications

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

A complete ab initio view of Orbach and Raman spin-lattice relaxation in a Dysprosium coordination compound

A Complete Ab Initio View of Orbach and Raman Spin–Lattice Relaxation in a Dysprosium Coordination Compound

Single-Ion Anisotropy and Intramolecular Interactions in CeIII and NdIII Dimers

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Magnetic Anisotropy Trends along a Full 4f-Series: The fⁿ⁺⁷ Effect

Single-Ion Anisotropy and Intramolecular Interactions in Ce^III and Nd^III Dimers