Microscopic spin Hamiltonian of a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cr</mml:mi></mml:mrow><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>antiferromagnetic ring from inelastic neutron scattering

Carretta, S.; Slageren, Joris van; Guidi, T.; Liviotti, E.; Mondelli, C.; Rovai, Donella; Cornia, Andrea; Dearden, Angela L.; Carsughi, F.; Affronte, Marco; Frost, C. D.; Winpenny, Richard E. P.; Gatteschi, Dante; Amoretti, G.; Caciuffo, R.

doi:10.1103/physrevb.67.094405

Cited by 137 publications

(115 citation statements)

References 32 publications

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“…The Cr 8 molecule contains eight Cr 3+ ions (s = 3/2) forming a nearly regular octagon [24,25]. It is one of the most studied MNMs both for its intrinsic interest and for being the precursor of a large family of heterometallic molecules and supramolecular complexes which are intensively studied for a number of fundamental and applicative issues [8,12,13,[26][27][28].…”

Section: The Cr8 Prototype Antiferromagnetic Ringmentioning

confidence: 99%

Spin dynamics of molecular nanomagnets unravelled at atomic scale by four-dimensional inelastic neutron scattering

et al. 2012

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Molecular nanomagnets are among the first examples of spin systems of finite size and have been test-beds for addressing a range of elusive but important phenomena in quantum dynamics. In fact, for short-enough timescales the spin wavefunctions evolve coherently according to the an appropriate cluster spin-Hamiltonian, whose structure can be tailored at the synthetic level to meet specific requirements. Unfortunately, to this point it has been impossible to determine the spin dynamics directly. If the molecule is sufficiently simple, the spin motion can be indirectly assessed by an approximate model Hamiltonian fitted to experimental measurements of various types. Here we show that recently-developed instrumentation yields the four-dimensional inelastic-neutron scattering function S(Q, E) in vast portions of reciprocal space and enables the spin dynamics to be determined with no need of any model Hamiltonian. We exploit the Cr8 antiferromagnetic ring as a benchmark to demonstrate the potential of this new approach. For the first time we extract a model-free picture of the quantum dynamics of a molecular nanomagnet. This allows us, for example, to examine how a quantum fluctuation propagates along the ring and to directly test the degree of validity of the Néel-vector-tunneling description of the spin dynamics.Mesoscopic systems can exhibit typical quantum dynamical phenomena, for instance by being able to tunnel through an energy barrier or by displaying long-lived coherent oscillations associated with superposition of states. This has attracted considerable interest for addressing fundamental issues and for the possible applications in quantum-information processing. Molecular nanomagnets (MNMs) are spin clusters where the topology of magnetic interactions can be tailored precisely at the synthetic level. They are metal-organic molecules containing a small number of magnetic ions whose spins are strongly coupled by exchange interactions. Shells of organic ligands provide magnetic separation between adjacent magnetic cores, which behave as identical and independent zero-dimensional units [1]. The magnetic dynamics are characterized by strong quantum fluctuations and this makes MNMs of great interest in quantum magnetism as model systems to investigate a range of phenomena, such as quantum-tunnelling of the magnetization [2-4], Néel-vector tunnelling (NVT) [5,6], quantum information processing [7][8][9], quantum entanglement [10-13] or decoherence [14][15][16]. Besides their fundamental interest, MNMs are also the focus of intense research for the potential technological applications as classical or quantum bits[1, 7-9, 17] and as magnetocaloric refrigerants [18]. A crucial aspect of the research on MNMs is the understanding of their low-temperature spin dynamics, especially of those aspects which are a direct manifestation of quantum mechanics like the tunneling of the Néel vector in antiferromagnetic rings. The most powerful technique to investigate the spin dynamics is inelastic neutron scattering (INS). INS m...

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Section: The Cr8 Prototype Antiferromagnetic Ringmentioning

confidence: 99%

Spin dynamics of molecular nanomagnets unravelled at atomic scale by four-dimensional inelastic neutron scattering

et al. 2012

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“…The energy levels obtained by the spin Hamiltonian 1.1 with parameters determined by means of Inelastic Neutron Scattering experiments [5] are shown in figure 1.4 as a function of the external magnetic field. In zero applied field the ground state is |S, M S = |0, 0 .…”

Section: Homometallic Cr 8 Afm Ringmentioning

confidence: 99%

“…4 Reference [17] reports the value H 2p (F) = 18 Tesla. 5 The numerical value of |ψ(0)| 2 2s has been evaluated by Hartree [23]. 6 Reference [17] reports the value H 2s (F) = 610 Tesla.…”

Section: F Nucleusmentioning

confidence: 99%

Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

Casadei

2011

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“…In particular, Cr 7 M rings (M = Zn, Cd, Mn, Ni) are derived from Cr 8 by substitution of one divalent cation M for a trivalent Cr ion 9 . Among them, Cr 7 Ni has been shown to be an excellent candidate to encode qubits 2,[10][11][12][13] . In addition, magnetically-open AF rings like Cr 8 Cd are reference systems to study the microscopic magnetic behaviour of finite AF chains 14 .…”

Section: Introductionmentioning

confidence: 99%

“…These systems have been also exploited to investigate the nature of the elementary excitations in finite AF systems 5,6 . One of the most studied AF rings is Cr 8 7 , which is formed by eight AF-coupled Cr 3+ ions (s = 3/2) [6][7][8] . Heterometallic rings with a magnetic ground state can be obtained from homonuclear ring by chemical substitution of one or two magnetic centers.…”

Section: Introductionmentioning

confidence: 99%

Relaxation dynamics in the frustratedCr9antiferromagnetic ring probed by NMR

et al. 2016

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We investigate the magnetic properties and the phonon-induced relaxation dynamics of the the first regular Cr9 antiferromagnetic (AF) ring, which represents a prototype frustrated AF ring. Geometrical frustration in Cr9 yields an energy spectrum with twofold degenerate low-lying levels and a low-spin ground state. The electronic relaxation dynamics is probed by 1 H-NMR through the temperature dependence of the spin-lattice relaxation rate 1/T1. We develop a microscopic model that reproduces 1/T1(T ) curves, taking also into account the wipeout effect. By interpreting these measurements we determine the spin-phonon coupling strength and we investigate the decay of the cluster magnetization due to the spin-phonon interaction. We find that at very low temperatures the relaxation is characterized by a single dominating Arrhenius-type relaxation process, whereas several relevant processes emerge at higher temperatures. In addition, we calculate the temperature and magnetic field dependence of level lifetimes.

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Microscopic spin Hamiltonian of aCr8antiferromagnetic ring from inelastic neutron scattering

Cited by 137 publications

References 32 publications

Spin dynamics of molecular nanomagnets unravelled at atomic scale by four-dimensional inelastic neutron scattering

Spin dynamics of molecular nanomagnets unravelled at atomic scale by four-dimensional inelastic neutron scattering

Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

Relaxation dynamics in the frustratedCr9antiferromagnetic ring probed by NMR

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