Theoretical Study of Screening Dependence of Aluminium Doped MgB_2  

作　　者：Gargee Sharma Smita Sharma 

机构地区：[1]Department of Physics, Government Dungar College

出　　处：《Chinese Physics Letters》2018年第3期79-83,共5页中国物理快报（英文版）

摘　　要：The screening dependence of superconducting state parameters （λ, μ＊, Tc, α and NoV） of six alloys of aluminium doped MgB2 systems are studied in the BCS-Eliashberg-MeMillan framework by employing five forms of dielectric screening function, viz. random phase approximation （RPA）, Harrison, Geldart and Vosko （GV）, Hubbard and Overhauser in conjunction with Ashcroft＇s potential. It is observed that electron-phonon coupling strength and Coulomb pseudopotential μ＊ are quite sensitive to the form of dielectric screening, whereas transition temperature Tc, isotope effect exponent α and effective interaction strength NoV show weak dependence on the form of dielectric screening function. It is found that the RPA form of dielectric screening function yields the best results for transition temperature Tc for all alloys of the Mg-Al-B system. The results obtained using GV screening are much higher than the experimental results. This shows that all the four dielectric screenings used here almost describe superconductivity in all the alloys of the Mg-Al-B system, but the GV screening is not suitable for such an alloy system.The screening dependence of superconducting state parameters （λ, μ＊, Tc, α and NoV） of six alloys of aluminium doped MgB2 systems are studied in the BCS-Eliashberg-MeMillan framework by employing five forms of dielectric screening function, viz. random phase approximation （RPA）, Harrison, Geldart and Vosko （GV）, Hubbard and Overhauser in conjunction with Ashcroft＇s potential. It is observed that electron-phonon coupling strength and Coulomb pseudopotential μ＊ are quite sensitive to the form of dielectric screening, whereas transition temperature Tc, isotope effect exponent α and effective interaction strength NoV show weak dependence on the form of dielectric screening function. It is found that the RPA form of dielectric screening function yields the best results for transition temperature Tc for all alloys of the Mg-Al-B system. The results obtained using GV screening are much higher than the experimental results. This shows that all the four dielectric screenings used here almost describe superconductivity in all the alloys of the Mg-Al-B system, but the GV screening is not suitable for such an alloy system.

关 键 词：Theoretical Study of Screening Dependence of Aluminium Doped MgB2 Al 

分 类 号：O511.3[一般工业技术—材料科学与工程]