Single‐Molecule Magnets Under Pressure

Bircher, Roland; Chaboussant, Grégory; Dobe, Christopher; Güdel, Hans U.; Ochsenbein, Stefan T.; Sieber, Andreas; Waldmann, Oliver

doi:10.1002/adfm.200500244

Cited by 149 publications

(56 citation statements)

References 68 publications

(113 reference statements)

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“…It has been 18 years since the discovery that the discrete CC 12 ) could possess an energy barrier to the reorientation of its molecular spin that was large enough to observe magnetic hysteresis below a blocking temperature (T B ) [29,30]. Such SMMs [31][32][33][34][35][36][37] can have magnetization relaxation times that are more than 10 8 times slower than normal paramagnets. This area thus represents a molecular, "bottom-up" approach to nanoscale magnets, complementary to the standard "top-down" approach to nanoparticles of traditional magnetic materials (e.g.…”

Section: Edited Feb 6mentioning

confidence: 99%

High-nuclearity cobalt coordination clusters: Synthetic, topological and magnetic aspects

Kostakis

Perlepes

Блатов

et al. 2012

Coordination Chemistry Reviews

209

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A c c e p t e d M a n u s c r i p t Research highlights We analyzed aspects of the synthetic, reactivity, structural and magnetic chemistry of Co CCs  We classified all the polynuclear Cobalt coordination clusters found in CCDC (CCDC 5.32 Nov. 2010) higher than 4.  All the known Co coordination clusters can be searched by cluster topological symbol and nuclearity, compound name, dimensionality and Refcode. Highlights

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Section: Edited Feb 6mentioning

confidence: 99%

High-nuclearity cobalt coordination clusters: Synthetic, topological and magnetic aspects

Kostakis

Perlepes

Блатов

et al. 2012

Coordination Chemistry Reviews

209

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“…Most of the SMMs which have been synthesized so far are based on 3d metal ions, and several of them were studied by INS, but mostly for the transitions within the ground-state multiplet (for reviews see Basler et al, 2003;Bircher et al, 2006). However, being related to anisotropy and not the exchange splittings, these studies shall not be further discussed here; Fe 8 may serve as a representative example.…”

Section: A Introductionmentioning

confidence: 99%

Magnetic Cluster Excitations

Fürrer

2010

Int. J. Mod. Phys. B

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Magnetic clusters, i.e., assemblies of a finite number (between two or three and several hundred) of interacting spin centers which are magnetically decoupled from their environment, can be found in many materials ranging from inorganic compounds, magnetic molecules, artificial metal structures formed on surfaces to metalloproteins. The magnetic excitation spectra in them are determined by the nature of the spin centers, the nature of the magnetic interactions, and the particular arrangement of the mutual interaction paths between the spin centers. Small clusters of up to four magnetic ions are ideal model systems to examine the fundamental magnetic interactions which are usually dominated by Heisenberg exchange, but often complemented by anisotropic and/or higher-order interactions. In large magnetic clusters which may potentially deal with a dozen or more spin centers, the possibility of novel many-body quantum states and quantum phenomena are in focus. In this review the necessary theoretical concepts and experimental techniques to study the magnetic cluster excitations and the resulting characteristic magnetic properties are introduced, followed by examples of small clusters demonstrating the enormous amount of detailed physical information which can be retrieved. The current understanding of the excitations and their physical interpretation in the molecular nanomagnets which represent large magnetic clusters is then presented, with an own section devoted to the subclass of the singlemolecule magnets which are distinguished by displaying quantum tunneling of the magnetization. Finally, some quantum many-body states are summarized which evolve in magnetic insulators characterized by built-in or field-induced magnetic clusters. The review concludes addressing future perspectives in the field of magnetic cluster excitations.

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“…Most work has been done on "single-molecule magnets" (SMMs), [1][2][3][4] which are high-spin molecules that retain magnetisation in the absence of a magnetic field due to anisotropy of the spin ground state. Secondly there has been much work on antiferromagnetically coupled (AFM) wheels.…”

Section: Introductionmentioning

confidence: 99%

Studies of Finite Molecular Chains: Synthesis, Structural, Magnetic and Inelastic Neutron Scattering Studies of Hexa‐ and Heptanuclear Chromium Horseshoes

Ochsenbein¹,

Tuna²,

Rancan³

et al. 2008

Chemistry A European J

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We report the synthesis and structural characterisation of a family of finite molecular chains, specifically [{[R(2)NH(2)](3)[Cr(6)F(11)(O(2)CCMe(3))(10)]}(2)] (in which R=nPr 1, Et 2, nBu 3), [{Et(2)NH}(2){[Et(2)NH(2)](3)[Cr(7)F(12)(O(2)CCMe(3))(12)][HO(2)CCMe(3)](2)}(2)] (4), [{[Me(2)NH(2)](3)[Cr(6)F(11)(O(2)CCMe(3))(10)]2.5 H(2)O}(4)] (5) and [{[iPr(2)NH(2)](3)[Cr(7)F(12)(O(2)CCMe(3))(12)]}(2)] (6). The structures all contain horseshoes of chromium centres, with each Cr...Cr contact within the horseshoe bridged by a fluoride and two pivalates. The horseshoes are linked through hydrogen bonds to the secondary ammonium cations in the structure, leading to di- and tetra-horseshoe structures. Through magnetic measurements and inelastic neutron scattering studies we have determined the exchange coupling constants in 1 and 6. In 1 it is possible to distinguish two exchange interactions, J(A)=-1.1 meV and J(B)=-1.4 meV; J(A) is the exchange interactions at the tips of the horseshoe and J(B) is the exchange within the body of the horseshoe (1 meV=8.066 cm(-1)). For 6 only one interaction was needed to model the data: J=-1.18 meV. The single-ion anisotropy parameters for Cr(III) were also derived for the two compounds as: for 1, D(Cr)=-0.028 meV and |E(Cr)|=0.005 meV; for 6, D(Cr)=-0.031 meV. Magnetic-field-dependent inelastic neutron scattering experiments on 1 allowed the Zeeman splitting of the first two excited states and level crossings to be observed. For the tetramer of horseshoes (5), quantum Monte Carlo calculations were used to fit the magnetic susceptibility behaviour, giving two exchange interactions within the horseshoe (-1.32 and -1.65 meV) and a weak inter-horseshoe coupling of +0.12 meV. Multi-frequency variable-temperature EPR studies on 1, 2 and 6 have also been performed, allowing further characterisation of the spin Hamiltonian parameters of these chains.

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Single‐Molecule Magnets Under Pressure

Cited by 149 publications

References 68 publications

High-nuclearity cobalt coordination clusters: Synthetic, topological and magnetic aspects

High-nuclearity cobalt coordination clusters: Synthetic, topological and magnetic aspects

Magnetic Cluster Excitations

Studies of Finite Molecular Chains: Synthesis, Structural, Magnetic and Inelastic Neutron Scattering Studies of Hexa‐ and Heptanuclear Chromium Horseshoes

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