Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling

10.26434/chemrxiv.12801164 ◽

2020 ◽

Author(s):

Mauro Perfetti ◽

Andrea Caneschi ◽

Taisiya S. Sukhikh ◽

Kira E. Vostrikova

Keyword(s):

Single Molecule ◽

Nitroxyl Radical ◽

Magnetic Coupling ◽

Magnetic Behavior ◽

Nitroxyl Radicals ◽

Antiferromagnetic Coupling ◽

Zero Field ◽

Effective Barrier ◽

Mononuclear Complexes ◽

Tricapped Trigonal Prism

A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable tripoidal oxazolidine nitroxyl radical were obtained in acetonitrile media starting from nitrates. The compounds, [LnRad(NO3)3] (Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl), have molecular structure. Their coordination polyhedron, LnO7N2, can be described as a tricapped trigonal prism with symmetry close to D3h. The value of 23 cm-1 for the antiferromagnetic coupling Gd-Rad established from the DC magnetic and EPR data is a record strength for the complexes of 4f-elements with nitroxyl radicals. The terbium derivative displays frequency-dependent out-of-phase signals in zero field indicating single-molecule magnetic behavior with an effective barrier of 57 cm-1.

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Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling

10.26434/chemrxiv.12801164.v2 ◽

2020 ◽

Author(s):

Mauro Perfetti ◽

Andrea Caneschi ◽

Taisiya S. Sukhikh ◽

Kira E. Vostrikova

Keyword(s):

Single Molecule ◽

Nitroxyl Radical ◽

Magnetic Coupling ◽

Magnetic Behavior ◽

Nitroxyl Radicals ◽

Antiferromagnetic Coupling ◽

Zero Field ◽

Effective Barrier ◽

Mononuclear Complexes ◽

Tricapped Trigonal Prism

A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable tripoidal oxazolidine nitroxyl radical were obtained in acetonitrile media starting from nitrates. The compounds, [LnRad(NO3)3] (Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl), have molecular structure. Their coordination polyhedron, LnO7N2, can be described as a tricapped trigonal prism with symmetry close to D3h. The value of 23 cm-1 for the antiferromagnetic coupling Gd-Rad established from the DC magnetic and EPR data is a record strength for the complexes of 4f-elements with nitroxyl radicals. The terbium derivative displays frequency-dependent out-of-phase signals in zero field indicating single-molecule magnetic behavior with an effective barrier of 57 cm-1.

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Hard versus soft: zero-field dinuclear Dy(iii) oxygen bridged SMM and theoretical predictions of the sulfur and selenium analogues

Dalton Transactions ◽

10.1039/c9dt00324j ◽

2019 ◽

Vol 48 (9) ◽

pp. 2872-2876 ◽

Cited By ~ 5

Author(s):

Kuduva R. Vignesh ◽

Dimitris I. Alexandropoulos ◽

Brian S. Dolinar ◽

Kim R. Dunbar

Keyword(s):

Magnetic Anisotropy ◽

Magnetic Coupling ◽

Magnetic Behavior ◽

Dinuclear Complexes ◽

Zero Field ◽

Theoretical Predictions

Structural, magnetic and CASSCF studies were used to quantify the observed magnetic behavior of two lanthanide dinuclear complexes. The effect of soft-donor atoms was probed in order to ascertain the effect of magnetic anisotropy combined with magnetic coupling in dinuclear SMMs.

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Antiferromagnetic coupling of TbPc2 molecules to ultrathin Ni and Co films

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.4.36 ◽

2013 ◽

Vol 4 ◽

pp. 320-324 ◽

Cited By ~ 32

Author(s):

David Klar ◽

Svetlana Klyatskaya ◽

Andrea Candini ◽

Bernhard Krumme ◽

Kurt Kummer ◽

...

Keyword(s):

Absorption Spectroscopy ◽

Single Molecule ◽

Magnetic Circular Dichroism ◽

Magnetic Coupling ◽

Magnetic Surface ◽

Antiferromagnetic Coupling ◽

Single Molecule Magnets ◽

X Ray ◽

X Ray Absorption

The magnetic and electronic properties of single-molecule magnets are studied by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. We study the magnetic coupling of ultrathin Co and Ni films that are epitaxially grown onto a Cu(100) substrate, to an in situ deposited submonolayer of TbPc2 molecules. Because of the element specificity of the X-ray absorption spectroscopy we are able to individually determine the field dependence of the magnetization of the Tb ions and the Ni or Co film. On both substrates the TbPc2 molecules couple antiferromagnetically to the ferromagnetic films, which is possibly due to a superexchange interaction via the phthalocyanine ligand that contacts the magnetic surface.

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The localized electron: magnetic properties

10.1093/oso/9780198814597.003.0002 ◽

2018 ◽

Author(s):

Jean-Pierre Launay ◽

Michel Verdaguer

Keyword(s):

Single Molecule ◽

Model Systems ◽

Ferromagnetic Coupling ◽

Single Chain ◽

Single Molecule Magnets ◽

Magnetic Systems ◽

Orbital Interactions ◽

Prussian Blue Analogues ◽

Mononuclear Complexes

After preliminaries about electron properties, and definitions in magnetism, one treats the magnetism of mononuclear complexes, in particular spin cross-over, showing the role of cooperativity and the sensitivity to external perturbations. Orbital interactions and exchange interaction are explained in binuclear model systems, using orbital overlap and orthogonality concepts to explain antiferromagnetic or ferromagnetic coupling. The phenomenologically useful Spin Hamiltonian is defined. The concepts are then applied to extended molecular magnetic systems, leading to molecular magnetic materials of various dimensionalities exhibiting bulk ferro- or ferrimagnetism. An illustration is provided by Prussian Blue analogues. Magnetic anisotropy is introduced. It is shown that in some cases, a slow relaxation of magnetization arises and gives rise to appealing single-ion magnets, single-molecule magnets or single-chain magnets, a route to store information at the molecular level.

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Complex magnetic properties associated with competing local and itinerant magnetism in $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$

Scientific Reports ◽

10.1038/s41598-021-90751-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mily Kundu ◽

Santanu Pakhira ◽

Renu Choudhary ◽

Durga Paudyal ◽

N. Lakshminarasimhan ◽

...

Keyword(s):

Heat Capacity ◽

Neutron Diffraction ◽

Single Phase ◽

Magnetic Transition ◽

Muon Spin Rotation ◽

Antiferromagnetic Coupling ◽

Diffraction Measurement ◽

Zero Field ◽

Crystalline Electric Field ◽

X Ray

AbstractTernary intermetallic compound $${\text {Pr}}_2 {\text {Co}}_{0.86} {\text {Si}}_{2.88}$$ Pr 2 Co 0.86 Si 2.88 has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ($$\mu$$ μ SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below $$\sim$$ ∼ 4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field $$\mu$$ μ SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below $$\sim$$ ∼ 20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

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Inducing Single Molecule Magnetic Behavior in a [Co4O4] Cubane via a Pronounced Solvatomagnetic Effect

Inorganic Chemistry ◽

10.1021/ic4027656 ◽

2014 ◽

Vol 53 (6) ◽

pp. 2976-2982 ◽

Cited By ~ 22

Author(s):

Felix J. Klinke ◽

Animesh Das ◽

Serhiy Demeshko ◽

Sebastian Dechert ◽

Franc Meyer

Keyword(s):

Single Molecule ◽

Magnetic Behavior

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Crystal Structure Dependence of Antiferromagnetic Coupling in FE/SI Multilayers

MRS Proceedings ◽

10.1557/proc-384-195 ◽

1995 ◽

Vol 384 ◽

Author(s):

R. P. Michel ◽

A. Chaiken ◽

M. A. Wall

Keyword(s):

Crystal Structure ◽

Magnetic Coupling ◽

Antiferromagnetic Coupling ◽

Temperature Dependent ◽

Layered Systems ◽

Metal Insulator ◽

Structure Dependence ◽

Metallic Conductor ◽

Metal Metal ◽

Cscl Structure

ABSTRACTRecent reports of temperature dependent antiferromagnetic coupling in Fe/Si multilayers have motivated the generalization of models describing magnetic coupling in metal/metal multilayers to metal/insulator and metal/semiconductor layered systems. Interesting dependence of the magnetic properties on layer thickness and temperature are predicted. We report measurements that show the antiferromagnetic (AF) coupling observed in Fe/Si multilayers is strongly dependent on the crystalline coherence of the silicide interlayer. Electron diffraction images show the silicide interlayer has a CsCl structure. It is not clear at this time whether the interlayer is a poor metallic conductor or a semiconductor so the relevance of generalized coupling theories is unclear.

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