铁基超导体A(Fe1-xMx)2As2 (A = Sr, Ba; M = Rh, Ir, Pt)的超导电性和相图.pdf

摘 要 自从F掺杂的RFeAsO (R = La, Ce, Pr, Nd, Sm和Gd) 超导电性的发现以来， Fe-As超导体引起了极大的关注。另一个具有ThCr Si 结构的砷化物体系AFe As 2 2 2 2 (A = Sr, Ba, Ca) 具有与RFeAsO完全相似的物理特性，是铁砷超导体的母体化合 物，在 140 K ~ 210 K范围内呈现了结构相变和磁相变。随着掺杂量的增加，超 导相出现，结构和磁相变被压制。在本课题研究中，我们合成了不同掺杂浓度 的多晶样品Sr(Fe Rh ) As ，Ba(Fe Ir ) As 和Ba(Fe Pt ) As ，并实验分析其 1−x x 2 2 1−x x 2 2 1−x x 2 2 电阻特性和磁化率等热力学性质，XRD和SEM的结果表明样品的单相性很好。 此外，我们得到了在电子掺杂的AFe2As2 （A = Sr和Ba ）型化合物中较高的超导 转变温度Tc和根据相变点和临界温度作出的相图，并分析了不同磁性原子（3d， 4d和 5d ）掺杂对超导电性和其他各项物性的影响。 关键词：铁砷超导体；Sr(Fe Rh ) As ；Ba(Fe Ir ) As ；Ba(Fe Pt ) As ； 1−x x 2 2 1−x x 2 2 1−x x 2 2 结构相变和磁相变；超导转变温度；相图。 1 Abstract Since the recent discovery of superconductivity in the F-doped RFeAsO (R = La, Ce, Pr, Nd, Sm, and Gd), the FeAs-based superconductors have attracted much attention. Another family of oxygen-free FeAs-based compounds with the ThCr Si -type structure AFe As (A = Sr, Ba, Ca) have completely similar physical 2 2 2 2 properties with RFeAsO. Structural and magnetic transitions are observed during 140 K ~ 210 K in these undoped compounds. Upon doping both the structural and the magnetic ordering get suppressed and superconductivity appears. In our report, Polycrystalline samples Sr(Fe Rh ) As , Ba(Fe Ir ) As and Ba(Fe Pt ) As 1−x x 2 2 1−x x 2 2 1−x x 2 2 were synthesized with different compositions. We investigated electrical resistivity, and magnetization and oth