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Sum rule analysis of Umklapp processes and Coulomb energy: application to cuprate superconductivity

Misha Turlakov·Anthony J. Leggett
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Abstract

The third moment frequency sum rule for the density-density correlation function is rederived in the presence of Umklapp processes. Upper and lower bounds on the electron-electron Coulomb energy are derived in two-dimensional and three-dimensional media, and the Umklapp processes are shown to be crucial in determining the spectrum of the density fluctuations (especially for the two-dimensional systems). This and other standard sum rules can be used in conjunction with experimental spectroscopies (electron-energy loss spectroscopy, optical ellipsometry, etc.) to analyse changes of the electron-electron Coulomb energy at the superconducting transition in cuprates.

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Misha Turlakov, Anthony J. Leggett. 2002-07-17. Sum rule analysis of Umklapp processes and Coulomb energy: application to cuprate superconductivity. https://doi.org/10.1103/physrevb.67.094517

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