Marion M. S. Barbeau, Martin Eckstein, Mikhail I. Katsnelson, Johan H. Mentink
SciPost Phys. 6, 027 (2019) ·
published 5 March 2019

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In order to have a better understanding of ultrafast electrical control of
exchange interactions in multiorbital systems, we study a twoorbital Hubbard
model at half filling under the action of a timeperiodic electric field. Using
suitable projection operators and a generalized timedependent canonical
transformation, we derive an effective Hamiltonian which describes two
different regimes. First, for a wide range of nonresonant frequencies, we find
a change of the bilinear Heisenberg exchange $J_{\textrm{ex}}$ that is
analogous to the singleorbital case. Moreover we demonstrate that also the
additional biquadratic exchange interaction $B_{\textrm{ex}}$ can be enhanced,
reduced and even change sign depending on the electric field. Second, for
special driving frequencies, we demonstrate a novel spincharge coupling
phenomenon enabling coherent transfer between spin and charge degrees of
freedom of doubly ionized states. These results are confirmed by an exact
timeevolution of the full twoorbital MottHubbard Hamiltonian.