Condensed Matter Theory Seminar | December 15, 14:00
Periodic driving of correlated systems: high-harmonic generation in the Mott insulator and parametric phonon excitation in superconductors
Driving systems out of equilibrium can provide new ways to control properties and extract new functions. Recent development of intense laser in a wide frequency range has led to intriguing observations such as light-induced superconductivity-like behaviors above the transition temperature [1], enhancement of the excitonic condensation [2] and high-harmonic generation in solid states [3]. Motivated by this intriguing situation, we have been developing nonequilibrium methods based on the dynamical mean-field theory (DMFT). Here we would like to present recent two applications of the nonequilibrium DMFT for the time-periodic steady states (Floquet DMFT). In the first part, we discuss the high-harmonic generation (HHG) in the Mott insulator under periodic AC driving [4]. We show that qualitative behavior of the HHG spectrum is different between weak and strong field regimes, which originates from qualitative difference in doublon/holon dynamics under the driving. We also discuss the similarity and the difference of the HHG intensity in the Mott insulator compared to that of semiconductors and disordered systems. In the second part, we discuss the effects of the parametric-phonon driving on conventional SC, which has been considered to enhance SC[5][6]. By studying transient dynamics and steady states, we demonstrate that even though the attractive interaction can be enhanced by the driving, SC is always suppressed, in particular, at the parametric resonance. Our systematic analysis shows that, in a wide parameter range, the heating of the system is the dominant effect and the parametric phonon driving has a negative effect on SC. [1] M. Mitrano et al., Nature 530, 461 (2016). [2] S. Mor et al., PRL 119, 086401 (2017). [3] S. Ghimire et al., Nat. Phys. 7, 138 (2011). [4] Y. Murakami, M. Eckstein, P. Werner to be published. [5] M. Knap et al., PRB 94, 214504 (2016); M. Babadi et al., PRB 96, 014512 (2017). [6] Y. Murakami et al, PRB 96, 045125 (2017).
Yuta Murakami, University of Fribourg
Seminar Room 0.03, ETP
Contact: Zala Lenarcic