Strong Axiality and Ising Exchange Interaction Suppress Zero-Field Tunneling of Magnetization of an Asymmetric Dy<sub>2</sub> Single-Molecule Magnet

Guo, Yun‐Nan; Xu, Gang; Wernsdorfer, Wolfgang; Ungur, Liviu; Guo, Yang; Tang, Jinkui; Zhang, Hongjie; Chibotaru, Liviu F.; Powell, Annie K.

doi:10.1021/ja205035g

Cited by 685 publications

(402 citation statements)

References 42 publications

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“…Compound 3 shows very different physics from the exchange bias type of compounds, originally described by Wernsdorfer et al 33 , and also seen in {Dy 2 } complexes 16 , where a remnant magnetization is present in the open hysteresis loops; a feature not observed here because of rapid zero-field relaxation. The hypothetical compound where the tilt angle is 0°may possibly show the characteristic QTM steps at the crossing points in Supplementary Fig.…”

Section: Discussioncontrasting

confidence: 40%

“…Radical bridging ligands can provide a strong magnetic exchange pathway between two lanthanide ions, leading to magnetic hysteresis at 14 K 3,4 . In other compounds weak Ln Á Á Á Ln interactions can shift the zero-field quantum tunnelling step to a finite field, known as exchange biasing 15 , with different effects on cryogenic magnetization curves depending on the sign of the exchange 16,17 or even mask single-ion slow relaxation modes 18 . More frequently, however, Ln Á Á Á Ln interactions increase quantum tunnelling rates, leading to apparently lower U eff values when compared with paramagnetic Ln ions doped into a diamagnetic lattice 8,17,19 .…”

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confidence: 99%

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Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

et al. 2014

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Lanthanide compounds show much higher energy barriers to magnetic relaxation than 3d-block compounds, and this has led to speculation that they could be used in molecular spintronic devices. Prototype molecular spin valves and molecular transistors have been reported, with remarkable experiments showing the influence of nuclear hyperfine coupling on transport properties. Modelling magnetic data measured on lanthanides is always complicated due to the strong spin-orbit coupling and subtle crystal field effects observed for the 4f-ions; this problem becomes still more challenging when interactions between lanthanide ions are also important. Such interactions have been shown to hinder and enhance magnetic relaxation in different examples, hence understanding their nature is vital. Here we are able to measure directly the interaction between two dysprosium(III) ions through multi-frequency electron paramagnetic resonance spectroscopy and other techniques, and explain how this influences the dynamic magnetic behaviour of the system.

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Section: Discussioncontrasting

confidence: 40%

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confidence: 99%

Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

et al. 2014

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“…An increasing number of ab initio CASSCF calculations 6,14,15,20,28 have shown that in most low-symmetry complexes, the ground Kramers doublet of Dy III is strongly axial with the principal values of the g-tensor approaching those of the m J ¼ ± 15 / 2 levels of the atomic multiplet 6 20). This empirical observation suggests that a simple, but appropriate, variational ansatz for the many-electron ground state wavefunction of these low-symmetry complexes consists of the atomic functions w ± (a,b) corresponding to the m J ¼ ± 15 / 2 states of the multiplet 6 H 15/2 .…”

Section: Many Electron Wavefunction and Electrostatic Minimizationmentioning

confidence: 99%

“…Recent advances in post Hartree-Fock multi-configurational ab initio methodology have made accurate quantum chemical calculations on paramagnetic 4f compounds possible 12 . The Complete Active Space Self Consistent Field (CASSCF) method can accurately predict the magnetic properties of lanthanide complexes 13,14 , and calculations of this type have become an indispensable tool for the explanation of increasingly interesting magnetic phenomena 6,[15][16][17] . These calculations are especially useful in cases of low symmetry, where previous methods have provided intractable, over parameterized problems 18,19 .…”

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confidence: 99%

An electrostatic model for the determination of magnetic anisotropy in dysprosium complexes

et al. 2013

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Understanding the anisotropic electronic structure of lanthanide complexes is important in areas as diverse as magnetic resonance imaging, luminescent cell labelling and quantum computing. Here we present an intuitive strategy based on a simple electrostatic method, capable of predicting the magnetic anisotropy of dysprosium(III) complexes, even in low symmetry. The strategy relies only on knowing the X-ray structure of the complex and the well-established observation that, in the absence of high symmetry, the ground state of dysprosium(III) is a doublet quantized along the anisotropy axis with an angular momentum quantum number m J ¼ ± 15 / 2 . The magnetic anisotropy axis of 14 low-symmetry monometallic dysprosium(III) complexes computed via high-level ab initio calculations are very well reproduced by our electrostatic model. Furthermore, we show that the magnetic anisotropy is equally well predicted in a selection of low-symmetry polymetallic complexes.

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“…More importantly, dinuclear Ln III SMMs are very important model systems to answer basic questions regarding single-ion relaxation vs. slow magnetic relaxation arising from the molecule as an entity. Thus, Ln III 2 complexes are highly desirable [10][11][12][13][14][15][16][17][18][19][20]. Another interesting area to which dinuclear lanthanide(III) complexes (and also mononuclear ones) are relevant is quantum computation; Ln III ions are promising candidates for encoding quantum information [21,22].…”

Section: Introductionmentioning

confidence: 99%

Using the Singly Deprotonated Triethanolamine to Prepare Dinuclear Lanthanide(III) Complexes: Synthesis, Structural Characterization and Magnetic Studies

et al. 2017

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Abstract:The 1:1 reactions between hydrated lanthanide(III) nitrates and triethanolamine (teaH 3 ) in MeOH, in the absence of external bases, have provided access to the dinuclear complexes [Ln 2 (NO 3 ) 4 (teaH 2 ) 2 ] (Ln = Pr, 1; Ln = Gd, 2; Ln = Tb, 3; Ln = Dy, 4; Ln = Ho, 5) containing the singly deprotonated form of the ligand. Use of excess of the ligand in the same solvent gives mononuclear complexes containing the neutral ligand and the representative compound [Pr(NO 3 )(teaH 3 ) 2 ](NO 3 ) 2 (6) was characterized. The structures of the isomorphous complexes 1·2MeOH, 2·2MeOH and 4·2MeOH were solved by single-crystal X-ray crystallography; the other two dinuclear complexes are proposed to be isostructural with 1, 2 and 4 based on elemental analyses, IR spectra and powder XRD patterns. The IR spectra of 1-6 are discussed in terms of structural features of the complexes. The two Ln III atoms in centrosymmetric 1·2MeOH, 2·2MeOH and 4·2MeOH are doubly bridged by the deprotonated oxygen atoms of the two η 1 :η 1 :η 1 :η 2 :µ 2 teaH 2 − ligands. The teaH 2 − nitrogen atom and six terminal oxygen atoms (two from the neutral hydroxyl groups of teaH 2 − and four from two slightly anisobidentate chelating nitrato groups) complete 9-coordination at each 4f-metal center. The coordination geometries of the metal ions are spherical-relaxed capped cubic (1·2MeOH), Johnson tricapped trigonal prismatic (2·2MeOH) and spherical capped square antiprismatic (4·2MeOH). O-H···O H bonds create chains parallel to the a axis. The cation of 6 has crystallographic two fold symmetry and the rotation axis passes through the Pr III atom, the nitrogen atom of the coordinated nitrato group and the non-coordinated oxygen atom of the nitrato ligand. The metal ion is bound to the two η 1 :η 1 :η 1 :η 1 teaH 3 ligands and to one bidentate chelating nitrato group. The 10-coordinate Pr III atom has a sphenocoronal coordination geometry. Several H bonds are responsible for the formation of a 3D architecture in the crystal structure of 6. Complexes 1-6 are new members of a small family of homometallic Ln III complexes containing various forms of triethanolamine as ligands. Dc magnetic susceptibility studies in the 2-300 K range reveal the presence of a weak to moderate intramolecular antiferromagnetic exchange interaction (J = −0.30(2) cm −1 based on the spin HamiltonianĤ = −J(Ŝ Gd1 ·Ŝ Gd1 )) for 2 and probably weak antiferromagnetic exchange interactions within the molecules of 3-5. The antiferromagnetic Gd III ···Gd III interaction in 2 is discussed in terms of known magnetostructural correlations for complexes possessing the {Gd 2 (µ 2 -OR) 2 } 4+ core. Ac magnetic susceptibility measurements in zero dc field for 3-5 do not show frequency dependent out-of-phase signals; this experimental fact is discussed and rationalized for complex 4 in terms of the magnetic anisotropy axis for each Dy III center and the oblate electron density of the metal ion.

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Strong Axiality and Ising Exchange Interaction Suppress Zero-Field Tunneling of Magnetization of an Asymmetric Dy₂ Single-Molecule Magnet

Cited by 685 publications

References 42 publications

Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

An electrostatic model for the determination of magnetic anisotropy in dysprosium complexes

Using the Singly Deprotonated Triethanolamine to Prepare Dinuclear Lanthanide(III) Complexes: Synthesis, Structural Characterization and Magnetic Studies

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Strong Axiality and Ising Exchange Interaction Suppress Zero-Field Tunneling of Magnetization of an Asymmetric Dy2 Single-Molecule Magnet

Cited by 685 publications

References 42 publications

Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

Direct measurement of dysprosium(III)˙˙˙dysprosium(III) interactions in a single-molecule magnet

An electrostatic model for the determination of magnetic anisotropy in dysprosium complexes

Using the Singly Deprotonated Triethanolamine to Prepare Dinuclear Lanthanide(III) Complexes: Synthesis, Structural Characterization and Magnetic Studies

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Strong Axiality and Ising Exchange Interaction Suppress Zero-Field Tunneling of Magnetization of an Asymmetric Dy₂ Single-Molecule Magnet