Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS) [electronic resource].

Published: Washington, D.C. : United States. Dept. of Energy. Office of Science, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description: 25 pages : digital, PDF file
Additional Creators: Argonne National Laboratory, United States. Department of Energy. Office of Science, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary

One of the most fundamental properties of an interacting electron system is its frequency- and wave-vector-dependent density response function, χ(q,ω). The imaginary part, χ"(q,ω), defines the fundamental bosonic charge excitations of the system, exhibiting peaks wherever collective modes are present. χ quantifies the electronic compressibility of a material, its response to external fields, its ability to screen charge, and its tendency to form charge density waves. Unfortunately, there has never been a fully momentum-resolved means to measure χ(q,ω) at the meV energy scale relevant to modern electronic materials. Here, we demonstrate a way to measure χ with quantitative momentum resolution by applying alignment techniques from x-ray and neutron scattering to surface high-resolution electron energy-loss spectroscopy (HR-EELS). This approach, which we refer to here as M-EELS" allows direct measurement of χ"(q,ω) with meV resolution while controlling the momentum with an accuracy better than a percent of a typical Brillouin zone. We apply this technique to finite-{\bf q} excitations in the optimally-doped high temperature superconductor, Bi₂Sr₂CaCu₂O_8+x (Bi2212), which exhibits several phonons potentially relevant to dispersion anomalies observed in ARPES and STM experiments. In conclusion, our study defines a path to studying the long-sought collective charge modes in quantum materials at the meV scale and with full momentum control.

Report Numbers

E 1.99:1418460

Subject(s)

Materials Science

Note

Published through SciTech Connect.
10/06/2017.
"139465"
SciPost Physics 3 4 ISSN 2542-4653 AM
Ali A. Husain; Matteo Mitrano; Melinda S. Rak; Peter Abbamonte; Anshul Kogar; Sean Vig; Luc Venema; Vivek Mishra; Peter D. Johnson; Genda D. Gu; Eduardo Fradkin; Michael R. Norman.
Center for Emergent Superconductivity
Gordon and Betty Moore Foundation
Alexander von Humboldt Foundation

Funding Information

AC02-06CH11357

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