Resonant Magnetization Tunneling in Mn12 Acetate: The Absence of Inhomogeneous Hyperfine Broadening

Abstract

We present the results of a detailed study of the thermally-assisted-resonant-tunneling relaxation rate of Mn12 acetate as a function of an external, longitudinal magnetic field and find that the data can be fit extremely well to a Lorentzian function. No hint of inhomogeneous broadening is found, even though some is expected from the Mn nuclear hyperfine interaction. This inconsistency implies that the tunneling mechanism cannot be described simply in terms of a random hyperfine field.

Some minor revisions, title changed, updated figures, two added notes, one added reference. RevTeX, 4 pages, 3 postscript figures. Submitted to Rapid Communications

References in corpus (4)

• High frequency EPR spectra of a molecular nanomagnet provide a key to understand Quantum Tunneling of the Magnetization
• Thermally Activated Resonant Magnetization Tunneling in Molecular Magnets: Mn_12Ac and others
• Low-Temperature Quantum Relaxation in a System of Magnetic Nanomolecules
• Lattice Distortion Mediated Paramagnetic Relaxation in High-Spin High-Symmetry Molecular Magnets

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• Spin tunneling via dislocations in Mn-12 acetate crystals
• Spin relaxation in Mn12-acetate
• Dislocation-induced spin tunneling in Mn-12 acetate
• Phonon superradiance and phonon laser effect in nanomagnets
• Proton NMR for Measuring Quantum-Level Crossing in the Magnetic Molecular Ring Fe10
• Low temperature magnetic hysteresis in Mn${}_{12}$ acetate single crystals
• Linewidth of single photon transitions in Mn${}_{12}$-acetate
• Nonlinear response of single-molecule nanomagnets: equilibrium and dynamical
• Extreme field-sensitivity of the magnetic tunneling in Fe-doped Li${}_3$N
• Magnetization of Mn_12 Ac in a slowly varying magnetic field: an ab initio study