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Reply to arXiv:2103.10268 `Comment on "Crossover of Charge Fluctuations across the Strange Metal Phase Diagram'''
Authors:
Ali Husain,
Matteo Mitrano,
Melinda S. Rak,
Samantha Rubeck,
Bruno Uchoa,
Katia March,
Christian Dwyer,
John Schneeloch,
Ruidan Zhong,
Genda D. Gu,
Peter Abbamonte
Abstract:
We recently reported [1,2] measurements of the charge density fluctuations in the strange metal cuprate Bi$_{2.1}$Sr$_{1.9}$Ca$_{1.0}$Cu$_{2.0}$O$_{8+x}$ using both reflection M-EELS and transmission EELS with $\leq$10 meV energy resolution. We observed the well-known 1 eV plasmon in this material for momentum $q\lesssim$ 0.12 r.l.u., but found that it does not persist to large $q$. For…
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We recently reported [1,2] measurements of the charge density fluctuations in the strange metal cuprate Bi$_{2.1}$Sr$_{1.9}$Ca$_{1.0}$Cu$_{2.0}$O$_{8+x}$ using both reflection M-EELS and transmission EELS with $\leq$10 meV energy resolution. We observed the well-known 1 eV plasmon in this material for momentum $q\lesssim$ 0.12 r.l.u., but found that it does not persist to large $q$. For $q\gtrsim0.12$ r.l.u., we observe a frequency-independent continuum, similar to that observed in early Raman scattering experiments [3,4], that correlates highly with the strange metal phase [2].
In his Comment (arXiv:2103.10268), Joerg Fink claims we do not see the plasmon, and that our results are inconsistent with optics, RIXS, and the author's own transmission EELS measurements with $\sim$100 meV resolution from the early 1990's [5,6]. The author claims we have made a trigonometry error and are measuring a larger momentum than we think. The author asserts that the two-particle excitations of cuprate strange metals are accurately described by weakly interacting band theory in RPA with corrections for conduction band carrier lifetimes and Umklapp effects.
Here, we show that the author's Comment is in contradiction with known information from the literature. At $q\lesssim0.12$ r.l.u. we see the same 1 eV plasmon as other techniques. Moreover we compute our momentum correctly, adjusting the sample and detector angles during an energy scan to keep $q$ fixed. The only discrepancy is between our data and the results of Ref. [5] for $q\gtrsim0.12$ r.l.u. where, because of the coarse resolution used, the data had to be corrected for interference from the elastic line. A reexamination of these corrections in early transmission EELS measurements would likely shed light on this discrepancy.
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Submitted 10 June, 2021; v1 submitted 6 June, 2021;
originally announced June 2021.
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Localization of high-energy electron scattering from atomic vibrations
Authors:
Christian Dwyer
Abstract:
Electrons with kinetic energies of the order 100 keV are capable of exciting atomic vibrational states from a distance of microns. Despite such a large interaction distance, our detailed calculations show that the scattering physics permits a high-energy electron beam to locate vibrational excitations with atomic-scale spatial resolution. Pursuits to realize this capability experimentally could po…
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Electrons with kinetic energies of the order 100 keV are capable of exciting atomic vibrational states from a distance of microns. Despite such a large interaction distance, our detailed calculations show that the scattering physics permits a high-energy electron beam to locate vibrational excitations with atomic-scale spatial resolution. Pursuits to realize this capability experimentally could potentially benefit numerous fields across the physical sciences.
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Submitted 24 January, 2014;
originally announced January 2014.
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On chemical order and interfacial segregation in $γ^\prime$ (AlAg$_2$) precipitates
Authors:
Julian M. Rosalie,
Christian Dwyer,
Laure Bourgeois
Abstract:
A detailed study has been carried out on $γ^\prime$ (AlAg$_2$) precipitates in Al-Ag and Al-Ag-Cu alloys to reconcile the conflicting reports on chemical ordering and stacking faults in this phase. High angle annular dark field scanning transmission electron microscopy and convergent beam electron diffraction show no indication of chemical ordering on alternate basal planes of $γ^\prime$ precipita…
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A detailed study has been carried out on $γ^\prime$ (AlAg$_2$) precipitates in Al-Ag and Al-Ag-Cu alloys to reconcile the conflicting reports on chemical ordering and stacking faults in this phase. High angle annular dark field scanning transmission electron microscopy and convergent beam electron diffraction show no indication of chemical ordering on alternate basal planes of $γ^\prime$ precipitates in alloys aged at 473 K for 2-23 h. Precipitates were visible as Ag-rich regions with 1-13 fcc$\rightarrow$hcp stacking faults, corresponding to $γ^\prime$ platelets with thicknesses ranging from 0.69-6.44 nm. There were no systematically absent thicknesses. Growth ledges with a riser height equal to the $c$-lattice parameter (0.46 nm) were directly observed for the first time. Genuine stacking faults within the precipitates were extremely rare and only observed in thicker precipitates. In precipitates with 1-3 stacking faults there was also substantial Ag in the surrounding fcc layers of the matrix, indicating that Ag strongly segregated to the broad, planar precipitate-matrix interfaces. This segregation is responsible for previous reports of stacking faults in $γ^\prime$ precipitates. The results indicate that the early stages of $γ^\prime$ precipitate growth are interfacially controlled.
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Submitted 19 January, 2014; v1 submitted 11 July, 2013;
originally announced July 2013.
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Quantitative chemical mapping at the atomic scale
Authors:
Huolin L. Xin,
Christian Dwyer,
David A. Muller
Abstract:
Atomic-scale mapping of the chemical elements in materials is now possible using aberration-corrected electron microscopes but delocalization and multiple scattering can confound image interpretation. Here we report atomic-resolution measurements with the elastic and inelastic signals acquired on an absolute scale. By including dynamical scattering in both the elastic and inelastic channels we obt…
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Atomic-scale mapping of the chemical elements in materials is now possible using aberration-corrected electron microscopes but delocalization and multiple scattering can confound image interpretation. Here we report atomic-resolution measurements with the elastic and inelastic signals acquired on an absolute scale. By including dynamical scattering in both the elastic and inelastic channels we obtain quantitative agreement between theory and experiment. Our results enable a close scrutiny of the inelastic scattering physics and demonstrate the possibility of element-specific atom counting.
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Submitted 23 October, 2011;
originally announced October 2011.