Archiv 2017

Vortragender: Michael Sentef

Superconductivity - IMPRS-UFAST focus course

IMPRS-UFAST focus course
This course covers the basic phenomenology and microscopic theory of superconductivity: - definition of superconductors and their thermodynamics - microscopic BCS theory: electron-phonon interaction, Fröhlich Hamiltonian, Cooper instability, mean-field theory, Bogoliubons [mehr]

Solid State Physics

IMPRS-UFAST core course
From a microscopic point of view, a solid is just a regular arrangement of atoms, embedded in a soup of electrons. Yet, a remarkably rich manifold of phenomena emerges from this simple starting point, ranging from simple metals and semiconductors to multiple kinds of magnetic order or superconductivity. In this course we will discuss basic properties of solids and their microscopic understanding. [mehr]

Michael Sentef - Light-enhanced electron-phonon coupling from nonlinear electron-phonon coupling

MPSD Seminar
In light of recent experiments suggesting light-induced superconductivity [1] as well as light-enhanced electron-lattice coupling [2] for strongly driven IR phonons, it is natural to ask for a minimal and generic theoretical model that predicts such enhancement effects of important couplings in different material classes. One idea that comes to mind is nonlinear electron-phonon coupling [3,4]. A quadratic coupling term of the form " g2 nel x2IR " is generically the lowest order symmetry-allowed direct coupling of an IR-active phonon coordinate xIR to the electronic density nel in systems with inversion symmetry. In this talk I will present model evidence for light-enhanced electron-phonon coupling and light-induced effective attraction between electrons based on nonlinear electron-phonon coupling [3], the latter of which was already discussed in a similar context in [4]. [1] M. Mitrano et al., Nature 530, 461 (2016) [2] E. Pomarico et al., Phys. Rev. B 95, 024304 (2017) [3] M. A. Sentef, arXiv: 1702.00952 [4] D. M. Kennes et al., Nature Physics (2017) , doi:10.1038/nphys4024, arXiv:1609.03802 [mehr]
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