next Q-MAC meetings in 2018:

3rd Q-MAC symposium in Venice, May 22-25, 2018.

Next regular meeting in Paris,       November 27-28, 2018.

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Antoine Georges leads the CCQ in New York

at the newly founded Flatiron Institute of the Simons Foundation.

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Publication Detail / Abstract

J. J. Mendoza-Arenas, F. J. Gómez-Ruiz, M. Eckstein, D. Jaksch, S. R. Clark

Ultra-fast control of magnetic relaxation in a periodically driven Hubbard model

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Motivated by cold atom and ultra-fast pump-probe experiments we study the melting of long-range antiferromagnetic order of a perfect Néel state in a periodically driven repulsive Hubbard model. The dynamics is calculated for a Bethe lattice in infinite dimensions with non-equilibrium dynamical mean-field theory. In the absence of driving melting proceeds differently depending on the quench of the interactions to hopping ratio U/J0 from the atomic limit. For U

J0decay occurs due to mobile charge-excitations transferring energy to the spin sector, while for J0U it is governed by the dynamics of residual quasi-particles. Here we explore the rich effects strong periodic driving has on this relaxation process spanning three frequency ω regimes: (i) high-frequency ωU,J0, (ii) resonant =U > J0 with integer l, and (iii) in-gap Uω > J0 away from resonance. In case (i) we can quickly switch the decay from quasi-particle to charge-excitation mechanism through the suppression of J0. For (ii) the interaction can be engineered, even allowing an effective U = 0 regime to be reached, giving the reverse switch from a charge-excitation to quasi-particle decay mechanism. For (iii) the exchange interaction can be controlled with little effect on the decay. By combining these regimes we show how periodic driving could be a potential pathway for controlling magnetism in antiferromagnetic materials. Finally, our numerical results demonstrate the accuracy and applicability of matrix product state techniques to the Hamiltonian DMFT impurity problem subjected to strong periodic driving.

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