TY - JOUR
T1 - Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)
AU - Vig, Sean
AU - Kogar, Anshul
AU - Mitrano, Matteo
AU - Husain, Ali A.
AU - Venema, Luc
AU - Rak, Melinda S.
AU - Mishra, Vivek
AU - Johnson, Peter D.
AU - Gu, Genda D.
AU - Fradkin, Eduardo
AU - Norman, Michael R.
AU - Abbamonte, Peter
N1 - Funding Information:
Funding information This work was supported by the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences under Award DE-AC02-98CH10886. P. A. acknowledges support from the EPiQS program of the Gordon and Betty Moore Foundation, grant GBMF4542. E. F. acknowledges DOE Award No. DE-SC0012368. M. M. acknowledges support from the Alexander von Humboldt Foundation.
Publisher Copyright:
Copyright S. Vig et al. This work is licensed under the Creative Commons Attribution 4.0 International License.
PY - 2017/10
Y1 - 2017/10
N2 - One of the most fundamental properties of an interacting electron system is its frequency- A nd wave-vector-dependent density response function, (q,!). The imaginary part, 00(q,!), defines the fundamental bosonic charge excitations of the system, exhibiting peaks wherever collective modes are present. 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 (q,!) at the meV energy scale relevant to modern electronic materials. Here, we demonstrate a way to measure 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 00(q,!) 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-q excitations in the optimally-doped high temperature superconductor, Bi2Sr2CaCu2O8+x (Bi2212), which exhibits several phonons potentially relevant to dispersion anomalies observed in ARPES and STM experiments. 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.
AB - One of the most fundamental properties of an interacting electron system is its frequency- A nd wave-vector-dependent density response function, (q,!). The imaginary part, 00(q,!), defines the fundamental bosonic charge excitations of the system, exhibiting peaks wherever collective modes are present. 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 (q,!) at the meV energy scale relevant to modern electronic materials. Here, we demonstrate a way to measure 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 00(q,!) 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-q excitations in the optimally-doped high temperature superconductor, Bi2Sr2CaCu2O8+x (Bi2212), which exhibits several phonons potentially relevant to dispersion anomalies observed in ARPES and STM experiments. 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.
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U2 - 10.21468/SciPostPhys.3.4.026
DO - 10.21468/SciPostPhys.3.4.026
M3 - Article
AN - SCOPUS:85095549431
SN - 2542-4653
VL - 3
JO - SciPost Physics
JF - SciPost Physics
IS - 4
M1 - 026
ER -