Pressure-induced enhancement of electron-phonon coupling in superconducting CaC6 from first principles

Lijun Zhang, Yu Xie, Tian Cui, Yan Li, Zhi He, Yanming Ma, and Guangtian Zou
Phys. Rev. B 74, 184519 – Published 14 November 2006

Abstract

The pressure effects on the electron-phonon coupling (EPC) in superconducting CaC6 have been extensively studied using first-principles calculations within the rigid muffin-tin approximation. It is found that pairing electrons are mainly attributed to the Ca 3d electrons mediated by Ca low-lying, in-plane phonon vibrations. An increase in mean square of the EPC matrix element I2 and a decrease in Ca low-lying phonon frequency with increasing pressure are mainly responsible for the experimental observation of enhanced superconducting transition temperature. Furthermore, Mulliken population analysis suggests that the pressure-induced charge transfers from Ca to the graphite layers might mainly contribute to the softening behavior of Ca in-plane phonons.

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  • Received 7 August 2006

DOI:https://doi.org/10.1103/PhysRevB.74.184519

©2006 American Physical Society

Authors & Affiliations

Lijun Zhang, Yu Xie, Tian Cui, Yan Li, Zhi He, Yanming Ma*, and Guangtian Zou

  • National Laboratory of Superhard Materials, Jilin University, Changchun 130012, People’s Republic of China

  • *Author to whom correspondence should be addressed. Electronic address: mym@jlu.edu.cn

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Issue

Vol. 74, Iss. 18 — 1 November 2006

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