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Ultrafast control; antiferromagnetism; Floquet theory; non-equilibrium dynamical mean-field theory
Abstract:
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 urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0001 from the atomic limit. For urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0002 decay occurs due to mobile charge‐excitations transferring energy to the spin sector, while for urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0003 it is governed by the dynamics of residual quasi‐particles. Here we explore the rich effects that strong periodic driving has on this relaxation process spanning three frequency ω regimes: (i) high‐frequency urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0004, (ii) resonant urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0005 with integer l, and (iii) in‐gap urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0006 away from resonance. In case (i) we can quickly switch the decay from quasi‐particle to charge‐excitation mechanism through the suppression of ν0. For (ii) the interaction can be engineered, even allowing an effective urn:x-wiley:00033804:media:andp201700024:andp201700024-math-0007 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.
