Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session K05: Optically Driven Correlated Electron Systems: Theory
8:00 AM–11:00 AM,
Wednesday, March 7, 2018
LACC Room: 152
Sponsoring Unit: DCMP
Abstract: K05.00002 : Electronic Squeezing of Pumped Phonons: Negative U and Transient Superconductivity*
8:36 AM–9:12 AM
Advances in light sources and time resolved spectroscopy have made it possible to excite specific atomic vibrations in solids and to observe the resulting changes in electronic properties but the mechanism by which phonon excitation causes qualitative changes in electronic properties, is still under debate. Here, we show that the dominant symmetry-allowed coupling between electron density and dipole active modes implies an electron density-dependent squeezing of the phonon state which provides an attractive contribution to the electron-electron interaction, independent of the sign of the bare electron-phonon coupling and with a magnitude proportional to the degree of laser-induced phonon excitation. Reasonable excitation amplitudes lead to non-negligible attractive interactions that may cause significant transient changes in electronic properties including superconductivity. The mechanism is generically applicable to a wide range of systems, offering a promising route to manipulating and controlling electronic phase behavior in novel materials. Building on these results we analyze the non-equilbrium response of the electronic system and discuss implications for experimentally accessible observables, such as optical conductivity.
*D.M.K. was supported by the Basic Energy Sciences Program of the U. S. Department of Energy under Grant No. SC-0012375 and DFG KE 2115/1-1
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