Raman study of carrier-overdoping effects on the gap in high- T c superconducting cuprates
Raman study of carrier-overdoping effects on the gap in high- T c superconducting cuprates
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高温超导铜氧化物中载流子过度掺杂对能隙影响的拉曼研究
DOI：
10.1103/physrevb.68.060506
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发表时间：
2003
影响因子：
3.7
通讯作者：
Akio Yamanaka
中科院分区：
文献类型：
--
作者：
T. Masui;M. Limonov;Hiroshi Uchiyama;Stephen Lee;Setsuko Tajima;Akio Yamanaka
研究了重掺杂$(\mathrm{Y},\mathrm{Ca}){\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$${(T}_{c}=65\mathrm{K})$和${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$${(T}_{c}=55\mathrm{K})$晶体中的拉曼散射。对于这两种晶体，${A}_{1g}$和${B}_{1g}$极化的电子对断裂峰大部分转移到接近$2{\ensuremath{\Delta}}_{0},$${\ensuremath{\Delta}}_{0}$的一半的低能处，这是最大的间隙。强烈提示s波混入d波超导序参量，从而在${B}_{1g}$通道中表现出库仑屏蔽效应。s波分量与过掺杂的逐渐混合不是由于晶体结构对称性的改变，而是所有高${T}_{c}$超导铜酸盐的共同特征。
Raman scattering in the heavily overdoped $(\mathrm{Y},\mathrm{Ca}){\mathrm{Ba}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ ${(T}_{c}=65\mathrm{K})$ and ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ ${(T}_{c}=55\mathrm{K})$ crystals has been investigated. For both the crystals, the electronic pair-breaking peaks in the ${A}_{1g}$ and ${B}_{1g}$ polarizations were largely shifted to the low energies close to a half of $2{\ensuremath{\Delta}}_{0},$ ${\ensuremath{\Delta}}_{0}$ being the maximum gap. It strongly suggests s-wave mixing into the d-wave superconducting order parameter and the consequent manifestation of the Coulomb screening effect in the ${B}_{1g}$ channel. Gradual mixing of s-wave component with overdoping is not due to the change of crystal structure symmetry but a generic feature in all high-${T}_{c}$ superconducting cuprates.