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Spektor, Marat

PhD student

Education

  • 2011- 2022, PhD Ultrafast Dynamics of Charge carriers in laser heated metals
    with Daniel Rich

    Abstract/Description: Short-pulse laser interaction with metals is a subject of practical engi-
    neering as well as fundamental scienti c research.
    From the point of view of fundamental science, short-pulse laser irradi-
    ation has the ability to bring material into a highly non-equillibrium state
    and provides unique insights into material behavior under extreme condi-
    tions that cannot be easily attained by any other means. Indeed, scattering
    between electrons and phonons or impurities/defects on the femtosecond
    time scale was already implicitly conceived in the rst microscopic theories
    of electrical resistance [1], and has been studied extensively under Three
    Temperature state conditions (e.g. in transport measurements) [2].
    However, only the rapid advances of time-resolved spectroscopy during
    the past decades have made it possible to distinguish directly the di er-
    ent elementary scattering mechanisms of photo-excited carriers. In these
    experiments, an ultrashort light pulse excites the electrons. This collec-
    tive electron excitation rapidly dephases, giving an excited, non-thermal
    distribution of interacting electrons. Consequently this non-equilibrium
    distribution will (i) redistribute its energy by scattering among the quasi
    particles themselves via electron-electron (e 􀀀 e) scattering, leading to in-
    ternal thermalization of the electronic system and (ii) transfer energy to
    the lattice via electron-phonon (e 􀀀 ph) scattering, leading to cooling and
    relaxation within the lattice.
    The e ects described so far have a local spatial impact on the dynam-
    ics of photo-excited carriers. The non-local nature of the spatio-temporal
    dynamics of electron and lattice temperatures is attributed to the di usion
    of heat in metals, which is crucial for a variety of applications of metal
    nanostructures.
    The main goal of the thesis is to research and analyze various processes
    related to the ultrafast dynamics of charge carriers in laser heated metals.
    In particular, analysis will be performed regarding the thermalization
    of charge carriers which can be attributed to the e 􀀀 e scattering e ect,
    the relaxation of carriers which can be attributed to the e 􀀀 ph scattering
    e ect and the non-local thermo-optical response that is due to the e ect
    of thermal conductivity and leads to heat di usion. Comparison between
    di erent time scales related to each one of the processes will be presented.
    Further, a thorough analysis of the optical properties of Au will be
    presented. According to our model, two additional e ects modify the di-
    electric function of Au: (i) the band shifting e ect, which is related to the
    temperature dependence of the chemical potential of Au and (ii) the dipole
    matrix element temperature dependence (DMETD), which is related to the
    temperature dependence of the dipole matrix element. As far as we know,
    none of these e ects and their physical interpretation has been presented
    in the current literature.
    The spatio-temporal dynamics of optically-induced transient Bragg grat-
    ings will be presented and analyzed for di erent excitation conditions.
    Finally, potential application of these phenomena in the eld of ultrafast
    optical switching will be discussed.

  • 2007- 2010, MSc AC Losses in High Temperature Superconductors under non –Sinusoidal Conditions
    with Reuben Shuker

Publications

  1. Spektor, M. And Meerovich, V. And Sokolovsky, V. And Prigozhin, L., "Ac Losses In Thin Coated Conductors Under Non-Sinusoidal Conditions", Superconductor Science & Technology 25, 025008 (2012)
  2. Furman, G. And Spektor, M. And Meerovich, V. And Sokolovsky, V., "Losses In Coated Conductors Under Nonsinusoidal Currents And Magnetic Fields", Journal Of Superconductivity And Novel Magnetism 24, 1045-1051 (2011)
  3. Sokolovsky, Vladimir And Meerovich, Victor And Spektor, Marat And Levin, George A. And Vajda, Istvan, "Losses In Superconductors Under Non-Sinusoidal Currents And Magnetic Fields", Ieee Transactions On Applied Superconductivity 19, 3344-3347 (2009)