SmFeAsO_(0.78)F_(0.22)中Mn掺杂对超导电性的抑制效应  

SUPPRESSION OF SUPERCONDUCTIVITY BY MN DOPING IN SmFeAsO_(0.78)F_(0.22)

作　　者：鲁俊超[1] 张昌锦[1] 皮雳[1,2] 谭舜[1,2] 张裕恒 

机构地区：[1]中国科学技术大学中科院强磁场研究中心,合肥230026 [2]中国科学技术大学微尺度国家实验室,合肥230026

出　　处：《低温物理学报》2011年第1期1-4,共4页Low Temperature Physical Letters

基　　金：科技部重大科学研究计划项目(批准号:2010CB923403);国家重点基础研究发展计划项目(批准号:2011CBA00111)资助的课题~~

摘　　要：本文报道了Mn替代Fe对最佳掺杂的Sm-1111体系超导电性的影响.通过电输运及磁性质的测量发现Mn对Fe的替代迅速抑制了超导电性.随着Mn含量的增加,体系的电阻率ρ和磁化率M逐渐增大.对于低掺杂x<0.25%和未掺杂样品,M接近零,对于x≤1%,M从室温到超导转变几乎不变,实验指出Fe2+失去其磁性.我们提出这是由于Fe的3d电子和As的4p电子与不同位置的Fe2+3d电子形成pdσ杂化而致,超导电性来源于杂化电子.从低掺杂样品的不同磁场下ρ～T关系上也得到从300K到超导几乎是直线以及场下ρ～T类似于Bi系高温超导体的反常行为.Mn3+对Fe2+的替代并未激起Fe的磁性,体系磁矩随Mn增加来源于Mn的局域磁矩.Mn离子的引入降低了电荷载流子的浓度,阻断了Fe-As-Fe的长程pdσ杂化,使超导电性受到抑制.In this paper,we reported the influence of Mn substitution to Fe on the superconductivity of optimal doped Sm-1111 system.By electric transport property and magnetism measurement,we found that superconductivity was quickly suppressed by Mn doping.The resistivity ρ and magnetization M all increase with the concentration of Mn ions increasing.For the samples with x 〈0.25%,M is close to zero.For the samples with x≤ 1%,M almost keeps unchanged from room temperature to above Tc.These results indicate that the Fe2＋ in the system has lost its magnetism.We suggest that this is because the 3d electrons of Fe ions hybridize with the 4p electrons of As and 3d electrons in other Fe sites.The hybridized electrons lead to superconductivity.From the ρ～T curves of low-Tdoped samples under different magnetic field,one can see that the curves are almost linear from 300 K to Tc,and the ρ～T relation under magnetic field is similar to that of Bi 2201 superconductors.The substitution of Mn3＋ for Fe2＋ does not induce the magnetism of Fe.The magnetization of the system comes from the local moment of Mn ions.The introduction of Mn ions decreases the concentration of the carriers and obstructs the long range Fe-As-Fe pdσ hybridization paths and suppresses the superconductivity.

关 键 词：SmFeAsO0.78F0.22 高温超导电性 MN 掺杂效应 

分 类 号：O511[理学—低温物理]