Review of NMR and μSR studies in the molecular nanomagnet Mn12-ac

Borsa, F.; Furukawa, Yuji; Lascialfari, A.

doi:10.1016/j.ica.2008.03.061

Cited by 9 publications

(3 citation statements)

References 33 publications

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“…Magnetic resonance techniques have been widely used for the characterization and the study of magnetic properties of SMM in bulk, that is, on large single crystals. Conventional NMR [205][206][207][208][209][210] and Muon Spin Rotation (mSR) 205,209,211,212 have been used to measure molecular spin dynamics down to the quantum regime. On the other hand, EPR and HFEPR (see for example ref.…”

Section: Magnetic Resonance Techniquesmentioning

confidence: 99%

Advances on structuring, integration and magnetic characterization of molecular nanomagnets on surfaces and devices

2012

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This critical review represents a concise revision of the different experimental approaches so far followed for the structuration of molecular nanomagnets on surfaces, since the first reports on the field more than ten years ago. Afterwards, a presentation of the different experimental approaches followed for their integration in sensors is described. Such work involves mainly two families of sensors and devices, microSQUIDs sensors and three-terminal devices for single-molecule detection. Finally the last section is devoted to a detailed revision of the different experimental techniques that can be used for the magnetic characterization of these systems on surfaces, ranging from magnetic circular dichroism to magnetic force microscopy. The use of these techniques to characterize other nanostructured magnetic materials, such as nanoparticles, is also revised. The aim is to give a broad overview of the last advances achieved with these techniques and their potential and evolution over the next years.

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Section: Magnetic Resonance Techniquesmentioning

confidence: 99%

Advances on structuring, integration and magnetic characterization of molecular nanomagnets on surfaces and devices

2012

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“…NMR has proved to be a powerful tool for investigating both static and dynamic properties of nanoscale molecular magnets. 25,26 The NMR spectrum gives us information on the hyperfine interaction of the nuclei with the local magnetic moments, in particular the "on-site" NMR spectrum of nuclei on magnetic ions provides direct information on the local magnetic moments of the magnetic ions. On the other hand, the nuclear spin lattice relaxation rate (1/T 1 ) directly probes the low-frequency spectral weight of spin fluctuations of the local magnetic moments.…”

Section: Introductionmentioning

confidence: 99%

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

Furukawa

2016

IJNT

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We present a comprehensive review of nuclear magnetic resonance (NMR) studies performed on three nanoscale molecular magnets with different configurations of geometrically frustrated antiferromagnetic (AFM) triangles, new spin frustration systems with different novel structures: (1) the isolated single AFM triangle K6[V15As6O42(H2O)]·8H2O (in short V15), (2) the spin ball [Mo72Fe30O252(Mo2O7(H2O))2 (Mo2O8H2(H2O))(CH3COO)12(H2O)91]·150H2O (in short Fe30 spin ball), and (3) the twisted triangular spin tube [(CuCl2tachH)3Cl]Cl2 (in short Cu3 spin tube). In the V15 nanomagnet, from 51 V NMR spectra observed at only below ∼ 0.1 K, we directly determined the local spin configuration in both the nonfrustrated total spin ST = 3/2 state at higher magnetic fields (H ≥ 2.7 T) and the two nearly degenerate ST = 1/2 ground states at lower magnetic fields (H ≤ 2.7 T). The dynamical magnetic properties of V15 were investigated by proton spin-lattice relaxation rate (1/T1) measurements. In the ST = 3/2 state, 1/T1 shows thermally activated behavior as a function of temperature. On the other hand, a temperature independent behavior of 1/T1 at very low temperatures is observed in the frustrated ST = 1/2 ground state below 2.7 Tesla. Possible origins for the peculiar behavior of 1/T1 will be discussed in terms of magnetic fluctuations due to spin frustrations. In Fe30 spin ball, static and dynamical properties of Fe 3+ (s = 5/2) have been investigated by proton NMR spectra and 1/T1 measurements. From the temperature dependence of 1/T1, the fluctuation frequency of the Fe 3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures. The spin freezing is also evidenced by the observation of a sudden broadening of 1 H NMR spectra below 0.6 K. Finally 1 H NMR data in the Cu spin tube will be described. An observation of magnetic broadening of 1 H NMR spectra at low temperatures below 1 K directly revealed a gapless ground state of the system. The 1/T1 measurements revealed an usual slow spin dynamics in the quasi one dimensional Cu3 spin tube.

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“…Quantum spin behaviors, characteristic of SMMs such as [Mn 12 O 12 (CH 3 COO) 16 (H 2 O) 4 ] and its analogs, 9 have been extensively studied by ac magnetic susceptibility, micro-SQUID, 10 high-frequency EPR, 11 solidstate NMR, and μSR techniques. 12 In contrast, the dipole inversion of molecular-based ferroelectrics has been reported in charge transfer (CT), proton transfer, and supramolecular rotator systems. 13 Dipole inversion within a one-dimensional π-stack system of the charge-transfer complex (tetrathiafulvalene)(chloranil) was reported and its temperature-dependent dielectric constants followed the Curie law.…”

Section: Introductionmentioning

confidence: 99%

Single molecule magnets with m-fluorobenzoate and difluoromethylacetate as polar ligands

et al. 2013

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Two new single molecule magnets (SMMs), [Mn(12)O(12)(CHF(2)COO)(16)(H(2)O)(4)]·2CH(2)Cl(2)·4H(2)O (1) and [Mn(12)O(12)(m-FPhCOO)(16)(H(2)O)(4)]·2(m-FPhCOOH)·7CH(2)Cl(2) (2), based on a disc-shaped {Mn(12)O(12)}-framework with difluoromethylacetate (CHF(2)COO(-)) and m-fluorobenzoate (m-FPhCOO(-)) as polar ligands were prepared in CH(2)Cl(2). Structural analyses by X-ray diffraction at 100 K showed orientationally disordered fluorine atoms in the CHF(2)COO(-) and m-FPhCOO(-) ligands of crystals 1 and 2, respectively. In crystal 1, the fluorine atoms at the axial coordination sites of the disc-like {Mn(12)O(12)}-framework exhibited large thermal parameters even at 100 K, suggesting that thermally activated rotation of the -CHF(2) groups along the C-COO axis occurred in the CHF(2)COO(-) ligands. The SMMs behaviors of crystals 1 and 2 showed magnetization hysteresis at 1.8 K and frequency-dependent in-phase and out-of-phase ac magnetic susceptibilities, characteristic of SMMs. Frequency-dependent dielectric responses as well as two Debye-type relaxation processes at ~100 and ~220 K were observed in crystal 1, while such responses were not observed in crystal 2. The activation energy and blocking temperature of the relaxation process for 1 were 12 kJ mol(-1) and 48 K, respectively, at ~100 K, whereas those at ~220 K were 66 kJ mol(-1) and 153 K, respectively. In 1 , the two polarization types at ~100 and ~220 K were associated with thermally activated fluctuations of the hydrogen-bonded crystalline H(2)O molecules and rotation of the -CHF(2) group in the CHF(2)COO(-) ligand.

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Review of NMR and μSR studies in the molecular nanomagnet Mn12-ac

Cited by 9 publications

References 33 publications

Advances on structuring, integration and magnetic characterization of molecular nanomagnets on surfaces and devices

Advances on structuring, integration and magnetic characterization of molecular nanomagnets on surfaces and devices

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

Single molecule magnets with m-fluorobenzoate and difluoromethylacetate as polar ligands

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