Quantum relaxation and quantum coherence in mesoscopic molecular magnets

Mettes, F. L.; Luìs, Fernando; Jongh, L.J. de

doi:10.1103/physrevb.64.174411

Cited by 48 publications

(56 citation statements)

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“…It was found early on that the magnetic specific heat in Fe 8 would be unmeasurable at very low temperatures and zero external field, because the spin-lattice relaxation time of the electron spins becomes much longer that the typical timescale of the experiment (∼ 10 3 s at most). However, by applying a large transverse magnetic field, the tunneling rate could be made large enough to recover the equilibrium magnetic specific heat [23,24]. Importantly, the case of Mn 12 -ac is different in that one could observe the contribution of the nuclear spins, which have a large specific heat at millikelvin temperatures.…”

Section: Resultsmentioning

confidence: 99%

Quantum Nanomagnets and Nuclear Spins: An Overview

Morello¹

2008

NATO Science for Peace and Security Series B: Physics and Biophysics

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Section: Resultsmentioning

confidence: 99%

Quantum Nanomagnets and Nuclear Spins: An Overview

Morello¹

2008

NATO Science for Peace and Security Series B: Physics and Biophysics

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“…The latter field, thus also the result of the quantum annealing process, depend on the experimental probe and its characteristic time scales. This dependence is shown in 1.7 that compares data derived for Mn 12 acetate using heat capacity [83] and magnetic neutron diffraction experiments [46].…”

Section: Quantum Annealingmentioning

confidence: 91%

Dipolar Magnetic Order in Crystals of Molecular Nanomagnets

Luis

2014

NanoScience and Technology

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Abstract. This chapter reviews experimental studies of long-range dipolar magnetic order, of which few examples exist in Nature, in crystals of single-molecule magnets. Quantum annealing by a transverse magnetic field enables one to explore the ground state of highly anisotropic SMMs, such as Mn12 and Fe8, both of which order ferromagnetically below Tc = 0.9 K and 0.6 K, respectively. In Mn12 acetate, molecular tilts caused by the disorder in the orientations of some solvent molecules affect dramatically the character of the field-induced transition, which agrees with the predictions of the random-field Ising model. The existence of a quantum critical point has been shown in crystals of Fe8 clusters, which are among the best realizations of the archetypical quantum Ising model in a transverse magnetic field.

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“…4. The specific heats of the cavity and sample are within an order of magnitude of each other at the experimental temperatures [19,20]. However, the cavity mass (∼10g) is many orders of magnitude larger than the sample's (∼0.5µg).…”

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Non-equilibrium magnetization dynamics in the Fe ₈ single-molecule magnet induced by high-intensity microwave radiation

et al. 2005

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PACS. 75.50.Xx -Molecular magnets. PACS. 76.30.-v -Electron paramagnetic resonance and relaxation. PACS. 75.45.+j -Macroscopic quantum phenomena in magnetic systems.Abstract. -Resonant microwave radiation applied to a single crystal of the molecular magnet Fe8 induces dramatic changes in the sample's magnetization. Transitions between excited states are found even though at the nominal system temperature these levels have negligible population. We find evidence that the sample heats significantly when the resonance condition is met. In addition, heating is observed after a short pulse of intense radiation has been turned off, indicating that the spin system is out of equilibrium with the lattice.Introduction. -Unlike classical magnets, single-molecule magnets, with spin values on the order of 10, have a discrete energy-level structure. This allows for the observation of resonant tunneling between "up" and "down" orientations when energy levels are brought into resonance by an external magnetic field [1-4]. The discrete level structure also permits radiation to drive transitions between states. Recent experiments show that microwave radiation can be used to enhance the rate for magnetization reversal [5,6] and change the equilibrium magnetization [7][8][9][10][11]. Much of this research is aimed at studying the spin dynamics of singlemolecule magnets in the presence of radiation with the goal of observing coherent dynamics such as Rabi oscillations and measuring the characteristic spin relaxation time T 1 and decoherence time T 2 . Measurements of these parameters are essential for determining whether single-molecule magnets are viable as potential qubits [12].In this letter, we show that high-amplitude radiation can induce dramatic changes in the equilibrium magnetization of the molecular magnet Fe 8 when the radiation frequency matches the energy difference between various energy levels in the system. This allows us to

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Quantum relaxation and quantum coherence in mesoscopic molecular magnets

Cited by 48 publications

References 54 publications

Quantum Nanomagnets and Nuclear Spins: An Overview

Quantum Nanomagnets and Nuclear Spins: An Overview

Dipolar Magnetic Order in Crystals of Molecular Nanomagnets

Non-equilibrium magnetization dynamics in the Fe ₈ single-molecule magnet induced by high-intensity microwave radiation

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Quantum relaxation and quantum coherence in mesoscopic molecular magnets

Cited by 48 publications

References 54 publications

Quantum Nanomagnets and Nuclear Spins: An Overview

Quantum Nanomagnets and Nuclear Spins: An Overview

Dipolar Magnetic Order in Crystals of Molecular Nanomagnets

Non-equilibrium magnetization dynamics in the Fe 8 single-molecule magnet induced by high-intensity microwave radiation

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Non-equilibrium magnetization dynamics in the Fe ₈ single-molecule magnet induced by high-intensity microwave radiation