Calendario Attività

Photoinduced coherent dynamics in strongly correlated systems: string states and Higgs modes

Categoria
Seminario
Data
27 Febbraio 2020 15:00 - 16:00
Luogo
14 - 15 IV piano St. 9
Email
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Affiliation
University of Fribourg, Ch. du Muse?e 3, CH-1700 Fribourg/Freiburg
Area di Ricerca
Superconduttivita', Sistemi fortemente correlati, Eterostrutture e loro applicazioni
File Allegato

The recent advances in nonequilibrium pump-probe time-domain spectroscopy opened new perspectives in studying qualitatively new properties of strongly correlated materials, which were previously inaccessible by other measuring methods. In particular, it allowed to disentangle the ultrafast response of different degrees of freedom by their temporal evolutions and opened an access to new effects, such as Higgs oscillations of the superconducting condensate. Using a non-equilibrium implementation of the dynamical mean field theory we present a theoretical study of the non-equilibrium dynamics in Mott insulators. Firstly, we simulate the relaxation of a photo-excited doped Mott insulator. We observed the appearance of string states after a weak photo excitation, which manifests itself in a nontrivial scaling of the relaxation time with the exchange coupling. Moreover, we found a correlated oscillatory evolution of the kinetic energy and spin-spin correlation function, which is a direct consequence of a strong spin-charge coupling [1]. Recently, the long-lived coherent oscillations at THz frequencies associated with the string states were experimentally measured in a strongly correlated NiO [2]. Secondly, within the framework of the density matrix formalism we study Higgs oscillations in one- and two-band superconductors, which allow to detect directly properties of the superconducting condensate as a function of time ([3]). In addition, the new interplay between the phase (Leggett) and amplitude (Higgs) modes is analyzed in detail and predictions are made [4]. [1] N. Bittner, D. Golez?, H. U. R. Strand, M. Eckstein, and P. Werner, PR B 97, 235125 (2018) [2] K. Gillmeister, D. Golez?, C.-T. Chiang, N. Bittner, Y. Pavlyukh, J. Berakdar, P.Werner, W. Widdra, arXiv:1909.00828 [3] L. Schwarz, B. Fauseweh, N. Tsuji, N. Cheng, N. Bittner, H. Krull, M. Berciu, G. S. Uhrig, A. P. Schnyder, S. Kaiser, and D. Manske, Nat. Commun. 11, 287 (2020) [4] H. Krull, N. Bittner, G. S. Uhrig, D. Manske, and A. P. Schnyder, Nat. Commun. 7, 11921 (2016)

 
 

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