超导薄膜FeSe和FeS0.5Se0.5的磁性与电子特性的研究  

Investigations on Magnetism and Electronic Properties of Superconducting Thin Films FeSe and FeS0.5Se0.5

作　　者：王鑫[1] 仲崇贵[1] 李桦 董正超[1] WANG Xin;ZHONG Chonggui;LI Hua;DONG Zhengchao(School of Sciences,Nantong University,Nantong 226019,China)

机构地区：[1]南通大学理学院

出　　处：《材料导报》2020年第4期68-72,共5页Materials Reports

基　　金：国家自然科学基金(11447229);江苏省自然科学基金(BK2012655);江苏省研究生科研与实践创新计划项目(KYCX18_2412)~~

摘　　要：作为磁性超导体系的重要组成部分,新型铁基超导薄膜FeSe已经成为凝聚态物理研究的热点。本工作基于密度泛函理论的第一性原理,研究了FeSe以及S原子替位掺杂FeS0.5Se0.5超导薄膜的磁性结构、磁矩、能带和电子特性。研究发现,FeSe和FeS0.5Se0.5的基态结构均为条形反铁磁性,且在布里渊区中心Γ点和边界M点的费米面上都分别出现了3个空穴型能带和2个电子型能带,两者的费米能级都主要由Fe-3d电子以及As-4p(S-3p)电子构成,并且费米面处的Fe-3d电子态密度几乎与总能态密度相等,说明体系的超导电性主要来源于平面层内的Fe离子。然而,与纯的FeSe相比,FeS0.5Se0.5薄膜费米面上电子-空穴口袋的嵌套减弱,Fe离子磁矩减小,体系的反铁磁性减弱,表明S离子的掺杂有利于增强体系的超导电性。As an important part of iron-based superconductors,FeSe superconducting materials have become a hot topic in the field of condensed matter physics.In this paper,the magnetic structure,energy band and electronic density of states of FeSe and S atoms substituted FeS0.5Se0.5 thin films are investigated using the first-principles calculations based on density function theory.Also the effects of S doping on the characteristics of FeSe superconducting film are analyzed in details.The research results show that the ground state of FeSe and FeS0.5Se0.5 are striped-type antiferromagnetic state.Their Fermi surfaces both contain three hole-type bands at the Brillouin zone center and two electron-type bands at the Brillouin zone corner.Furthermore,the Fermi energy of FeSe and FeS0.5Se0.5 films are mainly from a large number of Fe-3d electrons and a small amount of As-4p(S-3p)electrons,but also the density of states of Fe-3d states at Fermi level is almost equal to the total density of states,which further indicates that the superconductivity of system mainly originates from the Fe ions in the plane layer.Instead,compared with the pure FeSe,the FeS0.5 Se0.5 film has undergone some changes that the nesting of electron-hole pockets on Fermi surface become weakened and the localized magnetic moment of Fe ions decrease,resulting in the increase of the metal properties and the reduction of the antiferromagnetism.Our research reflects that the doped S ions are beneficial to improve the superconductivity of FeSe system.

关 键 词：超导电性 磁性结构 电子特性 

分 类 号：O469[理学—凝聚态物理]