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arXiv 1501.02420cond-mat.supr-con
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铜氧化物超导体中的动能驱动超导电性

Kinetic-energy driven superconductivity in cuprate superconductors

Shiping Feng, Yu Lan, Huaisong Zhao, Lulin Kuang, Ling Qin, Xixiao Ma

摘要:

铜氧化物超导体中的超导性发生在电荷载流子掺杂的莫特绝缘体上,其中的中心问题是什么机制导致超导(SC)转变温度以下的电阻损失?本文综述了动能驱动SC机制在铜氧化物超导体超导电性描述中的基本思想。动能驱动的超导性的机制是纯电子的,没有声子,其中电荷-载流子配对相互作用直接从动能通过在掺杂浓度的较高幂次中交换自旋激发而产生。这种动能驱动的d波SC态受SC能隙和准粒子相干性的共同控制,导致最大SC转变温度出现在最佳掺杂附近,然后在欠掺杂和过掺杂区域均降低。特别地,由自旋激发介导的相同的电荷-载流子相互作用在粒子-粒子通道中诱导SC态,也在粒子-空穴通道中产生正常态赝能隙态。正常状态的赝能隙交叉温度远大于SC转变温度在欠掺杂和最佳掺杂制度,然后单调下降时,掺杂的增加,最终消失在一起的超导性在SC圆顶的末端。这种动能驱动的超导机制也表明强电子关联有利于超导性,因为主要成分不是从外部自由度如声子而是仅仅从内部自旋自由度确定为电荷载流子配对机制。在动力学框架内讨论了铜氧化物超导体的典型性质。能量驱动的SC机制进行了综述。

英文摘要:

Superconductivity in cuprate superconductors occurs upon charge-carrier doping Mott insulators, where a central question is what mechanism causes the loss of electrical resistance below the superconducting (SC) transition temperature? In this review, we attempt to summarize the basic idea of the kinetic-energy driven SC mechanism in the description of superconductivity in cuprate superconductors. The mechanism of the kinetic-energy driven superconductivity is purely electronic without phonons, where the charge-carrier pairing interaction arises directly from the kinetic energy by the exchange of spin excitations in the higher powers of the doping concentration. This kinetic-energy driven d-wave SC-state is controlled by both the SC gap and quasiparticle coherence, which leads to that the maximal SC transition temperature occurs around the optimal doping, and then decreases in both the underdoped and overdoped regimes. In particular, the same charge-carrier interaction mediated by spin excitations that induces the SC-state in the particle-particle channel also generates the normal-state pseudogap state in the particle-hole channel. The normal-state pseudogap crossover temperature is much larger than the SC transition temperature in the underdoped and optimally doped regimes, and then monotonically decreases upon the increase of doping, eventually disappearing together with superconductivity at the end of the SC dome. This kinetic-energy driven SC mechanism also indicates that the strong electron correlation favors superconductivity, since the main ingredient is identified into a charge-carrier pairing mechanism not from the external degree of freedom such as the phonon but rather solely from the internal spin degree of freedom of the electron. The typical properties of cuprate superconductors discussed within the framework of the kinetic-energy driven SC mechanism are also reviewed.

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