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Title: Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)

Abstract

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, Bi 2Sr 2CaCu 2O 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 quantummore » materials at the meV scale and with full momentum control.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1];  [1];  [1];  [1];  [1];  [2];  [3];  [3];  [1];  [4]
  1. Univ. of Illinois, Urbana, IL (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Energy Frontier Research Center; Center for Emergent Superconductivity; Gordon and Betty Moore Foundation; Alexander von Humboldt Foundation; USDOE
OSTI Identifier:
1398288
Grant/Contract Number:
AC02-06CH11357; AC02-98CH10886; SC0012368
Resource Type:
Journal Article: Published Article
Journal Name:
SciPost Physics
Additional Journal Information:
Journal Volume: 3; Journal Issue: 4; Journal ID: ISSN 2542-4653
Publisher:
Stichting SciPost
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Husain, Ali A., Mitrano, Matteo, Rak, Melinda S., Abbamonte, Peter, Kogar, Anshul, Vig, Sean, Venema, Luc, Mishra, Vivek, Johnson, Peter D., Gu, Genda D., Fradkin, Eduardo, and Norman, Michael R.. Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS). United States: N. p., 2017. Web. doi:10.21468/SciPostPhys.3.4.026.
Husain, Ali A., Mitrano, Matteo, Rak, Melinda S., Abbamonte, Peter, Kogar, Anshul, Vig, Sean, Venema, Luc, Mishra, Vivek, Johnson, Peter D., Gu, Genda D., Fradkin, Eduardo, & Norman, Michael R.. Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS). United States. doi:10.21468/SciPostPhys.3.4.026.
Husain, Ali A., Mitrano, Matteo, Rak, Melinda S., Abbamonte, Peter, Kogar, Anshul, Vig, Sean, Venema, Luc, Mishra, Vivek, Johnson, Peter D., Gu, Genda D., Fradkin, Eduardo, and Norman, Michael R.. 2017. "Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)". United States. doi:10.21468/SciPostPhys.3.4.026.
@article{osti_1398288,
title = {Measurement of the dynamic charge response of materials using low-energy, momentum-resolved electron energy-loss spectroscopy (M-EELS)},
author = {Husain, Ali A. and Mitrano, Matteo and Rak, Melinda S. and Abbamonte, Peter and Kogar, Anshul and Vig, Sean and Venema, Luc and Mishra, Vivek and Johnson, Peter D. and Gu, Genda D. and Fradkin, Eduardo and Norman, Michael R.},
abstractNote = {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, Bi2Sr2CaCu2O8+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.},
doi = {10.21468/SciPostPhys.3.4.026},
journal = {SciPost Physics},
number = 4,
volume = 3,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.21468/SciPostPhys.3.4.026

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  • 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 resolutionmore » 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, Bi 2Sr 2CaCu 2O 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.« less
  • Electron-hole pair excitations in the insulating cuprates Sr{sub 2}CuO{sub 2}Cl{sub 2} were investigated by angle-resolved electron energy loss spectroscopy. The optically allowed and optically forbidden transitions were observed to be strongly anisotropic in Cu-O{sub 2} plane. The former show a large energy dispersion {approximately}1.5 eV along [110], and the latter appear at a higher energy position ({approximately}4.5 eV) only along [100], but not along [110]. We interpret these results as transitions involving excitons. A small exciton model is examined to explain both the observed features. {copyright} {ital 1996 The American Physical Society.}
  • Electron energy loss spectroscopy (EELS) is a powerful technique for studying Li-ion battery materials because the valence state of the transition metal in the electrode and charge transfer during lithiation and delithiation processes can be analyzed by measuring the relative intensity of the transition metal L₃ and L₂ lines. In addition, the Li distribution in the electrode material can be mapped with nanometer scale resolution. Results obtained for FeO 0.7F 1.3/C nanocomposite positive electrodes are presented. The Fe average valence state as a function of lithiation (discharge) has been measured by EELS and results are compared with average Fe valencemore » obtained from electrochemical data. For the FeO 0.7F 1.3/C electrode discharged to 1.5 V, phase decomposition is observed and valence mapping with sub-nanometer resolution was obtained by STEM/EELS analysis. For the lowest discharge voltage of 0.8 V, a surface electrolyte inter-phase (SEI) layer is observed and STEM/EELS results are compared with the Li–K edges obtained for various Li standard compounds (LiF, Li₂CO₃ and Li₂O).« less
  • Electron energy loss spectroscopy and density functional theory have been used to show that there is a covalent component to the bonding in NiAl, CoAl and FeAl, between the transition metal atom and Al. There is no charge transfer and no ionic component to the bonding in NiAl and probably not in CoAl and FeAl. The bonding is non-stoichiometric NiAl is studied. Preliminary results are given for a {Sigma}{sub 3} boundary in NiAl.