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Condensed Matter Physics Seminar

  • Date
    Wed, Nov 20

    Time
    4:00 PM — 5:00 PM

    Website
    http://forum.sci.ccny.cuny.edu/news-events/calendar-of-events/

    Address
    Marshak Science Building
    160 Convent Ave.
    New York, NY  10031

    Location
    Marshak Science Building, 418N

    p: 212.650.5618

    Admission
    Free

  • Event Details

    Enrique del Barco, Department of Physics, University of Central Florida, Orlando, Florida


    Quantum Tunneling of the Magnetization in Molecular Magnets: A Microscopic View

    Enrique del Barco

    Department of Physics, University of Central Florida, Orlando, Florida 32816, USA



    Intensive research efforts during the last few years have led to a significant enhancement of the current knowledge of magnetic bistability and quantum tunneling of the magnetization (MQT) in single-molecule magnets (SMMs). A good part of this new understanding has been allowed by studies of families of relatively simple, low-nuclearity transition metal clusters, where the low number of ions responsible for the magnetic behavior of the molecule enables a full numerical treatment of the multi-spin Hamiltonian, where degrees of freedom associated to the individual ions can be adequately tested. These include exchange and dipolar interactions, single-ion zero-field splitting tensors (i.e. single-ion anisotropy order and orientation), and intra-molecular symmetries, among others. In addition, comparisons between the giant spin and the multi-spin phenomenologies can be easily undertaken. Note that the giant spin approach assumes the molecule to behave as a rigid spin unit, leaving out the intra-molecular degrees of freedom, and ultimately failing to capture many of the key physics. In this talk I will summarize the most relevant results achieved by following this particular research approach, including the first observation of QTM selection rules that reflect the intrinsic symmetry of a SMM [1,2], and the observation of asymmetric quantum Berry phase interference patterns in a Mn-based SMM [3], among others, placing special emphasis in explaining the way internal molecular degrees of freedom intervene to shape these fundamental QTM properties.



    References:

    [1]        J. J. Henderson, C. Koo, P. L. Feng, E del Barco, S. Hill, I. S. Tupitsyn, P. C. E. Stamp and D. N. Hendrickson, Manifestation of spin selection rules on the quantum tunneling of magnetization in a single-molecule magnet, Phys. Rev. Lett. 103, 017202 (2009).

    [2]        J. Liu, E. del Barco and S. Hill. Quantum tunneling of magnetization in trigonal single-molecule magnets, Phys. Rev. B. 85, 012406 (2012).

    [3]        H. M. Quddusi, J. Liu, S. Singh, K. J. Heroux, E. del Barco, S. Hill, and D. N. Hendrickson, Asymmetric Berry-Phase Interference Patterns in a Single-Molecule Magnet, Phys. Rev. Lett. 106, 227201 (2011).




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