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Coherent modulation of the electron temperature and electron–phonon couplings in a 2D material

Authors :
Yingchao Zhang
Wenjing You
Peter M. Oppeneer
Margaret M. Murnane
Henry C. Kapteyn
Fairoja Cheenicode Kabeer
Michael Bauer
Zhensheng Tao
Xun Shi
Yigui Zhong
Kai Rossnagel
Pablo Maldonado
Source :
Proc Natl Acad Sci U S A
Publication Year :
2020
Publisher :
National Academy of Sciences, 2020.

Abstract

Ultrashort light pulses can selectively excite charges, spins and phonons in materials, providing a powerful approach for manipulating their properties. Here we use femtosecond laser pulses to coherently manipulate the electron and phonon distributions, and their couplings, in the charge density wave (CDW) material 1T-TaSe$_2$. After exciting the material with a short light pulse, spatial smearing of the electrons launches a coherent lattice breathing mode, which in turn modulates the electron temperature. This indicates a bi-directional energy exchange between the electrons and the strongly-coupled phonons. By tuning the laser excitation fluence, we can control the magnitude of the electron temperature modulation, from ~ 200 K in the case of weak excitation, to ~ 1000 K for strong laser excitation. This is accompanied by a switching of the dominant mechanism from anharmonic phonon-phonon coupling to coherent electron-phonon coupling, as manifested by a phase change of $\pi$ in the electron temperature modulation. Our approach thus opens up possibilities for coherently manipulating the interactions and properties of quasi-2D and other quantum materials using light.<br />Comment: 15 pages, 4 figures

Details

Language :
English
Database :
OpenAIRE
Journal :
Proc Natl Acad Sci U S A
Accession number :
edsair.doi.dedup.....605b445aa7b9837b5b4225efd03b81a6