铜氧超导电声耦合失效及强关联耦合实验证据  

EXPERIMENTALEVIDENCES OF NON-ELECTRIC-PHONON COUPLING AND STRONG CORRELATION MODE INCUPRATE SUPERCONDUCTORS

作　　者：郭志超[1] 陶慧[1] 刘岩[1] 李平林[1] 

机构地区：[1]河南省量子功能材料国际联合实验室,郑州大学物理工程学院,450001

出　　处：《低温物理学报》2015年第2期93-97,共5页Low Temperature Physical Letters

基　　金：国家自然科学基金(批准号:9493300);教育部博士点基金(批准号:9800462)资助的课题~~

摘　　要：铜氧高温超导丰富的物理属性使BCS理论遇到严峻挑战.一系列关于电子及空穴载流子的理论和实验研究结果显示,＂电声耦合＂在铜氧超导电性中失效.如铜氧超导的转变温度Tc与价电子密度之间构成非单调＂钟形＂曲线分布,而＂电声耦合＂下两者之间则表现为单调指数关系.同时,Hall效应实验揭示Tc与空穴载流子浓度的关系也为＂钟形＂轮廓.两类实验结果一致表明,无论是空穴配对还是电子配对,铜氧超导Cooper对配对机制不符合＂电声耦合＂特征.另外,关于铜氧超导拆对能隙的研究,目前已获得丰富的实验结果,飞秒激光和光子反射谱测量显示,拆对能隙分别达到1.5eV左右及1.2～2.1eV,只有电耦合才能达到如此大的耦合强度.因此,电耦合的＂激子＂可能是建立铜氧超导微观机制的合理途径.Ginzburg早年设想的高温超导激子模式或许在铜氧化合物中实现.The plentiful physical properties of high temperature copper-oxide superconductors make BCS theory encounter the austere challenge,because the electric-phonon coupling from BCS theory does not explain the high temperature superconductivity.A series of research results,for example,theoretical and experimental outcomes concerning the electrons and hole carriers in cuprates,show the relationship curve between the transition temperature Tcand the density of valence electrons as a non-monotone bell configuration.Then the electric-phonon coupling is breakdown in high temperature cuprates,because both relationships should behave as a monotone exponential curve under the electric-phonon coupling.Correspondingly,other kind of experimental results,Hall Effect data present the relationship curve between the Tcand the density of hole carriers behave yet as a non-monotone bell configuration.These two kinds of experimental curves indicate that the mechanism of carrier pairing in the cuprate superconductors is of non-electric-phonon coupling.On the other hand,some important experimental methods meas-ured the energy gap of pair breaking for high temperature superconductors,for example,the tested data from photon reflectance spectra and femto-second laser reveal that the energy gap is up to 1.2～2.1eV and 1.5eV around respectively.As well-known,such a large energy gap should only originate from the electric coupling,under which the exciton as a strong correlation mode might help us to get the better comprehension toward the microcosmic mechanism of cuprate superconductivity.Ginzburg＇s previous theoretical idea as the exciton mechanism for high temperature superconductivity has perhaps been achieved in cuprate compounds.

关 键 词：铜氧高温超导 耦合模式 载流子密度 拆对能隙 强关联 

分 类 号：O511[理学—低温物理]