论文标题
由于尖锐的kohn样软音符异常，可能会增强超导$ t_c $
Possible enhancement of the superconducting $T_c$ due to sharp Kohn-like soft phonon anomalies
论文作者
论文摘要
声子软化是凝结物质系统中普遍存在的现象，通常与电荷密度波（CDW）不稳定性和非谐度有关。声子软化，CDW和超导性之间的相互作用是激烈争论的话题。在这项工作中，根据最近开发的理论框架研究了异常的软声子不稳定性对超导性的影响，该框架在Migdal-Eliashberg理论中解释了声子阻尼和软化。模型计算表明，声子在声子分散关系中以声音或光学的尖锐倾角的形式软化（包括通常与CDW相关的Kohn-Type异常情况），可能会导致电子偶音偶联常数$λ$的歧管增加。在某些条件下，这与Bergmann和Rainer引入的最佳频率概念一致，可以产生大量的超导过渡温度$ T_C $。总而言之，我们的结果表明，通过利用在动量空间中限制的软声子异常来达到高温超导性的可能性。
Phonon softening is a ubiquitous phenomenon in condensed matter systems which is often associated with charge density wave (CDW) instabilities and anharmonicity. The interplay between phonon softening, CDW and superconductivity is a topic of intense debate. In this work, the effects of anomalous soft phonon instabilities on superconductivity are studied based on a recently developed theoretical framework that accounts for phonon damping and softening within the Migdal-Eliashberg theory. Model calculations show that the phonon softening in the form of a sharp dip in the phonon dispersion relation, either acoustic or optical (including the case of Kohn-type anomalies typically associated with CDW), can cause a manifold increase of the electron-phonon coupling constant $λ$. This, under certain conditions, which are consistent with the concept of optimal frequency introduced by Bergmann and Rainer, can produce a large increase of the superconducting transition temperature $T_c$. In summary, our results suggest the possibility of reaching high-temperature superconductivity by exploiting soft phonon anomalies restricted in momentum space.
