Synthesis and Characterization of Heterometallic {Cr<sub>7</sub>M} Wheels

Larsen, Finn; McInnes, Eric J. L.; Mkami, Hassane El; Overgaard, Jacob; Piligkos, Stergios; Rajaraman, Gopalan; Rentschler, Eva; Smith, Andrew A.; Smith, Graham; Boote, V.; Jennings, Martin D.; Timco, Grigore A.; Winpenny, Richard E. P.

doi:10.1002/ange.200390002

Cited by 118 publications

(169 citation statements)

References 16 publications

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“…A series of octa-nuclear hetero-nuclear wheels of general chemical formula [ (Affronte et al, 2007;Baker et al, 2011b;Larsen et al, 2003a;Laye et al, 2005), and their excitations studied by different techniques, among which were low-temperature torque magnetometry , high-frequency EPR (Piligkos et al, 2009), and INS (Baker et al, 2011b;Caciuffo et al, 2005). Also an analogous Fe 7 Mn cluster was investigated using INS .…”

Section: "Doped" Even-membered Antiferromagnetic Wheelsmentioning

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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Section: "Doped" Even-membered Antiferromagnetic Wheelsmentioning

confidence: 99%

Magnetic Cluster Excitations

Fürrer

2010

Int. J. Mod. Phys. B

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“…1b presents the same data as in Fig. 1a but the magnetization M is converted into a spin temperature T S using the equation [22]:with S = 1/2 and g = 2.1 [9]. Fig.…”

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confidence: 99%

“…with S = 1/2 and g = 2.1 [9]. used before qubit operations to reach extremely low temperatures even at relatively high cryostat temperatures.…”

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confidence: 99%

Resonant photon absorption and hole burning inCr7Niantiferromagnetic rings

et al. 2005

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Presented are magnetization measurements on a crystal of Cr7Ni antiferromagnetic rings. Irradiation with microwaves at frequencies between 1 and 10 GHz leads to observation of very narrow resonant photon absorption lines which are mainly broadened by hyperfin interactions. A two-pulse hole burning technique allowed us to estimate the characteristic energy diffusion time.PACS numbers: 75.50. Xx, 75.60.Jk, 75.75.+a, Magnetic molecules are currently considered among the most promising electron spin based quantum systems for the storing and processing of quantum information [1]. For this purpose, ferromagnetic [2] and antiferromagnetic [3,4] systems have attracted an increasing interest [5,6,7]. In the latter case the quantum hardware is thought of as a collection of coupled molecules, each corresponding to a different qubit. The main advantages would arise from the fact that they are extremely small and almost identical, allowing to obtain, in a single measurement, statistical averages of a larger number of qubits. The magnetic properties can be modelled with an outstanding degree of accuracy. And most importantly, the desired physical properties can be engineered chemically.Recently, the suitability of Cr-based antiferromagnetic molecular rings for the qubit implementation has been proposed [5,6,7]. The substitution of one metal ion in a Cr-based molecular ring with dominant antiferromagnetic couplings allowed to engineer its level structure and ground-state degeneracy [8,9]. A Cr 7 Ni molecular ring was characterized by means of low-temperature specificheat and torque-magnetometry measurements, thus determining the microscopic parameters of the corresponding spin Hamiltonian. The energy spectrum and the suppression of the leakage-inducing S-mixing render the Cr 7 Ni molecule a suitable candidate for the qubit implementation [6,7,10].In this paper we report the first micro-superconducting quantum interference device (micro-SQUID) [11] studies of the Cr 7 Ni molecular ring. Electron paramagnetic resonance (EPR) methods are combined with highsensitivity magnetization measurements. The magnetization detection could also be a Hall-probe magnetometer [12,13,14,15,16] The measurements were made in a dilution cryostat using a 20 µm sized single crystal of Cr 7 Ni. The magnetic probe was a micro-SQUID array [11,19] equipped with three coils allowing to apply a field in any direction and with sweep rates up to 10 T/s. The electromagnetic radiation was generated by a frequency synthesizer (Anritsu MG3694A) triggered with a nanosecond pulse generator. This setup allows to vary continuously the frequency from 0.1 Hz to 20 GHz, with pulse lengths form ∼1 ns to continuous radiation [20]. Using a 50 µm sized gold radio frequency (RF) loop, the RF radiation field was directed in a plane perpendicular to the applied static field µ 0 H. The microwave power of the generator could be varied from -80 to 20 dBm (10 −11 to 10 −1 W). The sample absorbes only a small fraction of the generator power. This fraction is however proportional t...

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“…Probably the first case of molecular dimer reported in the literature is the [ [24] and purple [3] Cr 7 Ni, after their respective colour. The first attempt of linking two green Cr 7 Ni rings was through the internal amine and different metallorganic groups [25].…”

Section: Chemical Routes For Linking Moleculesmentioning

confidence: 99%

Spin entanglement in supramolecular structures

Troiani¹,

Bellini²,

Candini³

et al. 2010

Nanotechnology

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Abstract.Molecular spin clusters are mesoscopic systems whose structural and physical features can be tailored at the synthetic level. Besides, their quantum behavior is directly accessible in laboratory and their magnetic properties can be rationalized in terms of microscopic spin models. Thus they represent an ideal playground within solid state systems to test concepts in quantum mechanics. One intriguing challenge is to control entanglement between molecular spins. Here we show how this goal can be pursued by discussing specific examples and referring to recent achievements.arXiv:1002.0450v1 [cond-mat.mes-hall]

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Synthesis and Characterization of Heterometallic {Cr₇M} Wheels

Abstract: furans and trisubstituted pyrroles that possess an aryl sulfanyl or alkyl sulfanyl substituent at C3 has been developed.

Cited by 118 publications

References 16 publications

Magnetic Cluster Excitations

Magnetic Cluster Excitations

Resonant photon absorption and hole burning inCr7Niantiferromagnetic rings

Spin entanglement in supramolecular structures

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Synthesis and Characterization of Heterometallic {Cr7M} Wheels

Abstract: furans and trisubstituted pyrroles that possess an aryl sulfanyl or alkyl sulfanyl substituent at C3 has been developed.

Cited by 118 publications

References 16 publications

Magnetic Cluster Excitations

Magnetic Cluster Excitations

Resonant photon absorption and hole burning inCr7Niantiferromagnetic rings

Spin entanglement in supramolecular structures

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Synthesis and Characterization of Heterometallic {Cr₇M} Wheels