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Electron-energy-loss and optical-transmittance investigation of Bi2Sr2CaCu2O8

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dc.contributorVirginia Techen
dc.contributor.authorWang, Y. Y.en
dc.contributor.authorFeng, G. F.en
dc.contributor.authorRitter, Alfred L.en
dc.contributor.departmentPhysicsen
dc.date.accessed2014-04-23en
dc.date.accessioned2014-05-07T15:36:56Zen
dc.date.available2014-05-07T15:36:56Zen
dc.date.issued1990-07en
dc.description.abstractThe energy-loss function Im(-1/ε) of Bi2Sr2CaCu2O8 has been measured over the range Eloss=0.8 to 80 eV by transmission electron-energy-loss spectroscopy (EELS) (nonimaging). The energy and momentum resolution were 0.1 eV and 0.04 Å-1, respectively. The low-energy spectra (Eloss≤3 eV) were studied as a function of momentum transfer (0.1 Å-1≤q≤0.3 Å-1). A well-defined peak in the loss function at Eloss∼1 eV is observed to disperse with momentum proportional to q2. This excitation is analyzed in terms of both an intracell, charge-transfer exciton model and the free-carrier (plasmon) model. The derived effective mass of the exciton mtot/m≃1.0 is far too small for a localized exciton. Using the free-carrier model and random-phase-approximation expressions for the dispersion coefficient, the carrier density and carrier effective mass can be determined separately. From our data and similar measurements by Nücker et al. [Phys. Rev. B 39, 12 379 (1989)], it is found that the effective mass roughly scales with carrier density. A heuristic model is introduced based on the assumption that low-energy gaps exist in portions of the Fermi surface due to structural instabilities. The model suggests how the effective mass could appear to scale with carrier density and why a single Drude term (with frequency-independent effective mass) does not describe the mid- to far-infrared optical spectra. Finally, the optical transmittance of the EELS sample was measured and the spectra analyzed in terms of the free-carrier model.en
dc.identifier.citationWang, Y. Y.; Feng, G. F.; Ritter, A. L., "Electron-energy-loss and optical-transmittance investigation of Bi2Sr2CaCu2O8," Phys. Rev. B 42, 420 DOI: http://dx.doi.org/10.1103/PhysRevB.42.420en
dc.identifier.doihttps://doi.org/10.1103/PhysRevB.42.420en
dc.identifier.issn0163-1829en
dc.identifier.urihttp://hdl.handle.net/10919/47839en
dc.identifier.urlhttp://journals.aps.org/prb/abstract/10.1103/PhysRevB.42.420en
dc.language.isoen_USen
dc.publisherAmerican Physical Societyen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectphysics, condensed matteren
dc.titleElectron-energy-loss and optical-transmittance investigation of Bi2Sr2CaCu2O8en
dc.title.serialPhysical Review Ben
dc.typeArticle - Refereeden

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