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arXiv 1507.03583cond-mat.supr-concond-mat.str-el
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金属超导电性在电荷密度波序开始时的增强

Enhancement of superconductivity at the onset of charge-density-wave order in a metal

Yuxuan Wang, Andrey V. Chubukov

摘要:

我们分析了超导性的铜氧化物附近的一个无公度的电荷密度波(CDW)的动量${\bf Q} = (Q,0)/(0,Q)$,在实验中观察到的顺序的发病。我们首先考虑一个半唯象的电荷-费米子模型,其中热费米子被${\bf Q}$隔开,通过交换软CDW涨落相互吸引。我们发现在CDW跃迁附近的量子临界区,$T_c = A {\bar g}_c$,其中${\bar g}_c$是电荷-费米子耦合,$A$是我们明确计算的前因子。然后,我们考虑特定的微观情况下,CDW序参量出现作为一个复合领域的初级自旋密度波场。我们证明了电荷-费米子耦合${\bar g}_c$是自旋-费米子耦合${\bar g}_s$的量级。因此,超导$T_c$的CDW秩序的开始附近大大增强。最后分析了外加磁场$H$的影响。我们发现,随着$H$的增加,最佳的$T_c$减少和超导圆顶变得越来越局限于CDW量子临界点。这些结果与实验结果一致。

英文摘要:

We analyze superconductivity in the cuprates near the onset of an incommensurate charge density wave (CDW) order with momentum ${\bf Q} = (Q,0)/(0,Q)$, as observed in the experiments. We first consider a semi-phenomenological charge-fermion model in which hot fermions, separated by ${\bf Q}$, attract each other by exchanging soft CDW fluctuations. We find that in a quantum-critical region near CDW transition, $T_c = A {\bar g}_c$, where ${\bar g}_c$ is charge-fermion coupling and $A$ is the prefactor which we explicitly compute. We then consider the particular microscopic scenario in which CDW order parameter emerges as a composite field made out of primary spin-density-wave fields. We show that charge-fermion coupling ${\bar g}_c$ is of order of spin-fermion coupling ${\bar g}_s$. As the consequence, superconducting $T_c$ is substantially enhanced near the onset of CDW order. Finally we analyze the effect of an external magnetic field $H$. We show that, as $H$ increases, optimal $T_c$ decreases and the superconducting dome becomes progressively more confined to the CDW quantum-critical point. These results are consistent with the experiments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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