Doping and momentum dependence of coupling strength in cuprate superconductors
Doping and momentum dependence of coupling strength in cuprate superconductors
复制标题
铜酸盐超导体中耦合强度的掺杂和动量依赖性
DOI：
10.1080/14786435.2019.1635722
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发表时间：
2019-03
影响因子：
1.6
通讯作者：
Feng Shiping
中科院分区：
文献类型：
--
作者：
Mou Yingping;Liu Yiqun;Tan Shuning;Feng Shiping
超导性是由电子之间通过交换玻色子激励而产生的相互作用引起的，然而，这种粘合形成的电子对表现为电子对玻色子激励的耦合强度。本文在动能驱动的超导机制下，研究了铜超导体中电子耦合强度对自旋激发的掺杂和动量依赖关系。利用粒子-空穴通道中的正常自能和粒子-粒子通道中电子通过自旋激发交换相互作用产生的配对自能，分别提取了电子与粒子-空穴通道和粒子-粒子通道中自旋激发的耦合强度。如图所示，粒子-空穴和反极周围粒子-粒子通道的耦合强度由两个峰组成，在最佳掺杂状态下，在5 meV处有一个尖锐的低能峰，在40 meV处有一个以弱峰为中心的宽带。特别是粒子-空穴通道中耦合强度的双峰结构可以持续到正常状态，而粒子-粒子通道中的耦合强度在节点处消失。然而，随着掺杂量的增加，欠掺杂区峰的位置向高能量方向移动。更具体地说，虽然峰的位置从反望远镜到热点的能量较低，但峰的权重随着动量从反望远镜到热点的移动而减小，并在热点处逐渐消失。
ABSTRACT Superconductivity is caused by the interaction between electrons by the exchange of bosonic excitations, however, this glue forming electron pairs is manifested itself by the coupling strength of the electrons to bosonic excitations. Here the doping and momentum dependence of the coupling strength of the electrons to spin excitations in cuprate superconductors is studied within the kinetic-energy-driven superconducting mechanism. The normal self-energy in the particle-hole channel and pairing self-energy in the particle-pariticle channel generated by the interaction between electrons by the exchange of spin excitation are employed to extract the coupling strengths of the electrons to spin excitations in the particle-hole and particle-particle channels, respectively. It is shown that below , both the coupling strengths in the particle-hole and particle-particle channels around the antinodes consist of two peaks, with a sharp low-energy peak located at 5 meV in the optimally doped regime, and a broad-band with a weak peak centred at 40 meV. In particular, this two-peak structure in the coupling strength in the particle-hole channel can persist into the normal-state, while the coupling strength in the particle-particle channel vanishes at the nodes. However, the positions of the peaks in the underdoped regime shift towards to higher energies with the increase of doping. More specifically, although the positions of the peaks move to lower energies from the antinode to the hot spot, the weights of the peaks decrease with the move of the momentum from the antinode to the hot spot, and fade away at the hot spots.
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