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

作　　者：Ru-Yi Zhao Xun-Wang Yan Miao Gao 赵如意;闫循旺;高淼(Department of Physics,School of Physical Science and Technology,Ningbo University,Ningbo 315211,China;College of Physics and Engineering,Qufu Normal University,Qufu 273165,China)

机构地区：[1]Department of Physics,School of Physical Science and Technology,Ningbo University,Ningbo 315211,China [2]College of Physics and Engineering,Qufu Normal University,Qufu 273165,China

出　　处：《Chinese Physics B》2021年第7期413-419,共7页中国物理B（英文版）

基　　金：the National Natural Science Foundation of China(Grant Nos.11974194 and 11974207);K.C.Wong Magna Fund in Ningbo University。

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 Sr BC under pressure.Different from Li BC and Mg B2,our calculations surprisingly reveal that Sr BC is isotropic in compressibility,due to the accumulation of substantial electrons in the interstitial region.We find that the Sr phonons strongly couple with B-2 pz orbital and the interstitial states,giving rise to a two-gap superconductivity in Sr BC,whose transition temperature shows an inverted V-shaped dependence on pressure.The maximal transition temperature is about 22 K at50 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.

关 键 词：SrBC phonon-mediated superconductivity anisotropic Eliashberg theory first-principles calculation maximally localized Wannier functions 

分 类 号：O511.3[一般工业技术—材料科学与工程]