Inverted V-shaped evolution of superconducting temperature in SrBC under pressure

• 作者: Ru-Yi Zhao Xun-Wang Yan Miao Gao
• 来源期刊: 中国物理B（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROP-ERTIES
• 页码范围: 469-476
• 页数: 8页
• 语种: 英文
• DOI: 10.1088/1674-1056/abfbcc

摘要

Based on density functional first-principles calculations and anisotropic Eliashberg equations,we have investigated the electronic structure,lattice dynamics,and phonon-mediated superconductivity in newly synthesized layered compound SrBC under pressure.Different from LiBC and MgB2,our calculations surprisingly reveal that SrBC is isotropic in com-pressibility,due to the accumulation of substantial electrons in the interstitial region.We find that the Sr phonons strongly couple with B-2pz orbital and the interstitial states,giving rise to a two-gap superconductivity in SrBC,whose transition temperature shows an inverted V-shaped dependence on pressure.The maximal transition temperature is about 22 K at 50 GPa.On both sides of 50 GPa,the transition temperature exhibits quasi-linear variation with positive and negative slopes,respectively.Such a variation of transition temperature is infrequent among phonon-mediated superconductors.The competition between enhanced electron-phonon matrix element and hardened phonons plays an essential role in governing the behavior of the critical temperature.