Actions for Ultrafast Gap Dynamics and Electronic Interactions in a Photoexcited Cuprate Superconductor [electronic resource].

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Ultrafast Gap Dynamics and Electronic Interactions in a Photoexcited Cuprate Superconductor [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
Article numbers 1,412,782 : digital, PDF file
Additional Creators
Brookhaven National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
We perform time- and angle-resolved photoemission spectroscopy (trARPES) on optimally doped Bi2Sr2CaCu2O8+δ (BSCCO-2212) using sufficient energy resolution (9 meV) to resolve the k-dependent near-nodal gap structure on time scales where the concept of an electronic pseudotemperature is a useful quantity, i.e., after electronic thermalization has occurred. We study the ultrafast evolution of this gap structure, uncovering a very rich landscape of decay rates as a function of angle, temperature, and energy. We explicitly focus on the quasiparticle states at the gap edge as well as on the spectral weight inside the gap that “fills” the gap—understood as an interaction, or self-energy effect—and we also make high resolution measurements of the nodal states, enabling a direct and accurate measurement of the electronic temperature (or pseudotemperature) of the electrons in the system. Rather than the standard method of interpreting these results using individual quasiparticle scattering rates that vary significantly as a function of angle, temperature, and energy, we show that the entire landscape of relaxations can be understood by modeling the system as following a nonequilibrium, electronic pseudotemperature that controls all electrons in the zone. Furthermore, this model has zero free parameters, as we obtain the crucial information of the SC gap Δ and the gap-filling strength ΓTDoS by connecting to static ARPES measurements. The quantitative and qualitative agreement between data and model suggests that the critical parameters and interactions of the system, including the pairing interactions, follow parametrically from the electronic pseudotemperature. In conclusion, we expect that this concept will be relevant for understanding the ultrafast response of a great variety of electronic materials, even though the electronic pseudotemperature may not be directly measurable.
Report Numbers
E 1.99:bnl--114804-2017-ja
bnl--114804-2017-ja
Subject(s)
Note
Published through SciTech Connect.
10/20/2017.
"bnl--114804-2017-ja"
"KC0207010"
Physical Review. X 7 4 ISSN 2160-3308; PRXHAE AM
S. Parham; H. Li; T. J. Nummy; J. A. Waugh; X. Q. Zhou; J. Griffith; J. Schneeloch; R. D. Zhong; G. D. Gu; D. S. Dessau.
Funding Information
SC0012704
PM015
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