Scientific Interests

I am an experimentalist investigating mostly the properties of magnetic and superconducting material. I have worked on materials such as spin glasses, frustrated magnets, molecular magnets, and high temperature superconductors. I used experiential techniques such as muon and nuclear spin resonance, magnetometers, transport, and crystal growth.

My most important finding up to day is:

  1. Common energy scale for magnetism and superconductivity:
    I managed to show that superconductivity and magnetism in the cuprate superconductors share a common energy scale, namely, Tc and the superexchange interaction strength are proportional to each other.

Other important findings are:

  1. Mapping exotic spin correlations in spin glasses:
    We found experimentally that close to the spin glass transition temperature Tg, the field dependent polarization of a probing spin P(H,t) scales like t/H. We interpreted this behavior using power law correlation function.
  2. The character of excitations in frustrated magnets:
    In frustrated magnets small groups of spins can rotate without changing the systems energy. One consequence of this motion is the possibility of strong dynamical spin fluctuations even as the temperature approaches zero. We found experimentally (by muon T1 measurements) that the dynamics in some frustrated magnets prevail even in the limit of zero temperature.
  3. Frustration driven distortion:
    Although it has been shown theoretically that spins on a pyrochlore lattice cannot order at any temperature, in reality these systems are rare. A possible reason for a phase transitions in real materials into magnetically ordered states is the coupling of the lattice with the spins. We found evidence for this magneto-elastic coupling in a study of the pyrochlore Y2Mo2O7 using Y NMR.
  4. Dephasing time on molecular magnets:
    We performed the only study existing to day of magnetic material where the spin value S is the variable. For that purpose we use isotropic molecular magnets (MM) with S ranging from 7/2 to 27/2. We found the dephasing time to be S independent and similar to 10 nsec.
  5. Light emitted from molecular magnets:
    We found (by accident) that when molecular magnets undergo quantum transitions, light is emitted from them. This light should have frequency of about 100GHz.
© 2013-2018 Amit Keren, The Technion Department of Physics. All Rights Reserved