摘要
超导电性是凝聚态物理学中研究的热点．超导材料基本构成分为电子型与空穴型．对于空穴型超导材料，其电子配对对称性普遍接受的是具有dx^2-y^-波对称性；而对于电子型超导材料，电子配对对称性是dx^2-y^2波对称性还是s波对称性，目前还存在着很大的争议．在线性近似下，dx^2-y^2波超导体超流密度是温度的线性函数，而S波超导体的超流密度是温度的指数函数．因此通过对超流密度的研究可以明确电子型超导材料的电子配对对称性．本文首先从微观t—t＇-t＇＇-J模型出发，通过隶波色子平均场近似，计及反铁磁关联序和超导配对项，得到两带超导哈密顿量，进而推导出两带超流密度．最后验证了电子掺杂型超导体电子配对对称性和空穴掺杂型一样，同样具有dx^2-y^2波对称性，和早期唯象的两带模型的研究相一致．明确超流密度随掺杂的变化，是两带准粒子随掺杂变化相互作用的结果．
Temperature superconductivity has been a hot issue in study of condensed matter physics. The basic form of superconductors is divided into the E- type and holetype. For holedoped cuprate superconductors,it is commonly accepted that the pairing order parameter has dxx^-y^z -wave symmetry. For electrondoped cuprate superconductors, it is a big dispute that the pairing order parameter either has dx^2-y^2 - wave symmetry or has s - wave symmetry. We know for the dx^2-y^2 wave superconductors that the superfluid density is temperature of linear functions at low temperature and for the swave superconductors the superfluid density is an exponential function of temperature. Therefore, the pairing symmetry can be e electron-type superconducting materials. Based on the t xplicitly t~ - t＂ determined by the superfluid density of -J model at slave- boson mean- field approximation, by taking into account the antiferromagnetic correlation order and superconducting pairing, we present the two- band superconducting Hamiltonian and derive the two- band superfluid density. We confirm that the electrondoped superconducting pairing symmetry is the same as the hole- doped superconducting, and them are all of dx^2-y^2 -wave symmetry,consistent with the earlier two band models by phenomenological. The superfluid density changes with doping,is because of quasi - particles in two band accompany with interaction with the doping.
出处
《物理通报》
2014年第1期115-119,共5页
Physics Bulletin
关键词
两带模型
费米面
超流响应
电子掺杂
配对对称性
Two - ban d m odel
Fermi surface
Superfluid respon s
Electron - doped
Pairin g sym m etry
