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Pressure dependence of the superconducting transition temperature of compressed LaH10

Chongze Wang, Seho Yi, and Jun-Hyung Cho
Phys. Rev. B 100, 060502(R) – Published 7 August 2019
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Abstract

Two recent experiments [M. Somayazulu et al. Phys. Rev. Lett. 122, 027001 (2019) and A. P. Drozdov et al., Nature (London) 569, 528 (2019)] reported the discovery of superconductivity in the fcc phase of LaH10 at a critical temperature Tc between 250and260K under a pressure of about 170 GPa. However, the dependence of Tc on pressure showed different patterns, i.e., the former experiment observed a continuous increase of Tc up to 275K on further increase of pressure to 202 GPa, while the latter one observed an abrupt decrease of Tc with increasing pressure. Here, based on first-principles calculations, we reveal that for the fccLaH10 phase, softening of the low-frequency optical phonon modes of H atoms dramatically occurs as pressure decreases, giving rise to a significant increase of the electron-phonon coupling (EPC) constant. Meanwhile, the electronic band structure near the Fermi energy is insensitive to change with respect to pressure. These results indicate that the pressure-dependent phonon softening is unlikely associated with Fermi-surface nesting, but driven by effective screening with the electronic states near the Fermi energy. It is thus demonstrated that the strong variation of EPC with respect to pressure plays a dominant role in the decrease of Tc with increasing pressure, supporting the measurements of Drozdov et al.

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  • Received 14 July 2019
  • Revised 28 July 2019

DOI:https://doi.org/10.1103/PhysRevB.100.060502

©2019 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Chongze Wang, Seho Yi, and Jun-Hyung Cho*

  • Department of Physics, Research Institute for Natural Science, and HYU-HPSTAR-CIS High Pressure Research Center, Hanyang University, 222 Wangsimni-ro, Seongdong-Ku, Seoul 04763, Republic of Korea

  • *Corresponding author: chojh@hanyang.ac.kr

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Issue

Vol. 100, Iss. 6 — 1 August 2019

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