Power-law Kohn anomaly in undoped graphene induced by Coulomb interactions

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2012
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American Physical Society
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Phonon dispersions generically display nonanalytic points, known as Kohn anomalies, due to electron-phonon interactions. We analyze this phenomenon for a zone-boundary phonon in undoped graphene. When electron-electron interactions with coupling constant \beta are taken into account, one observes behavior demonstrating that the electrons are in a critical phase: the phonon dispersion and lifetime develop power-law behavior with \beta-dependent exponents. The observation of this signature would allow experimental access to the critical properties of the electron state, and would provide a measure of its proximity to an excitonic insulating phase.
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De Juan, F., & Fertig, H. A. (2012). Power-law Kohn anomaly in undoped graphene induced by Coulomb interactions. Physical Review B - Condensed Matter and Materials Physics, 85(8), 085441. http://dx.doi.org/10.1103/PhysRevB.85.085441
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© 2012 American Physical Society
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