Seminars Archive
Ultrafast control of the magnetic exchange interaction
Condensed Matter Division, Max Planck Research Department for Structural Dynamics, University of Hamburg, Germany
Abstract
Magnetic order in condensed matter systems is determined by the exchange interaction J, the strongest force in magnetism. In this talk I discuss two pathways to modify J with ultrashort laser pulses, which are photo-doping [1] (exciting a nonequilibrium distribution of doublon and hole carriers in a Mott insulator), or coherent control of J with a laser that is not resonant to the charge transfer excitation. For the latter case, analytical Floquet theory for small clusters predict even the possibility to reverse the sign of the exchange coupling under very strong driving. We use nonequilibrium dynamical mean-field theory (DMFT) for the Hubbard model in infinite dimensions, and exact diagonalization for a one-dimensional system to numerically verify the possibility of such a controlled variation of J.
[1] J.H. Mentink and M. Eckstein, arXiv:1401.5308.
