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arXiv 1704.05282cond-mat.supr-con
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超导体正常态中的临界对涨落:赝能隙和准粒子阻尼

Critical pairing fluctuations in the normal state of a superconductor: pseudogap and quasi-particle damping

Philipp Lange, Oleksandr Tsyplyatyev, Peter Kopietz

摘要:

本文研究了临界对涨落对三维干净超导体正常态电子性质的影响。利用泛函重整化群方法考虑临界涨落的非高斯性质,我们在微观上证明了在BCS体系中,当逆相干长度远小于费米波矢时,临界对涨落对$ T_c \sqrt{Gi} \ln ( 80 / Gi )$阶准粒子阻尼的非解析贡献,其中Ginzburg-Levanyuk数$Gi$是临界区域宽度的无量纲度量。因此,在$T_c$之上存在温度窗口,其中由于临界配对波动引起的准粒子阻尼可以大于由于非临界散射过程引起的通常的$T^2$ -费米液体阻尼。另一方面,在强耦合区,其中$Gi$是为了统一,我们发现,准粒子阻尼由于临界配对涨落是成正比的温度。此外,我们发现在临界温度附近的$T_c$的电子态密度表现出波动诱导的赝能隙。我们还利用泛函重整化群方法导出了费米系统中由对相互作用引起的各种类型的超导不稳定性过程,并对它们进行了分类。

英文摘要:

We study the effect of critical pairing fluctuations on the electronic properties in the normal state of a clean superconductor in three dimensions. Using a functional renormalization group approach to take the non-Gaussian nature of critical fluctuations into account, we show microscopically that in the BCS regime, where the inverse coherence length is much smaller than the Fermi wavevector, critical pairing fluctuations give rise to a non-analytic contribution to the quasi-particle damping of order $ T_c \sqrt{Gi} \ln ( 80 / Gi )$, where the Ginzburg-Levanyuk number $Gi$ is a dimensionless measure for the width of the critical region. As a consequence, there is a temperature window above $T_c$ where the quasiparticle damping due to critical pairing fluctuations can be larger than the usual $T^2$-Fermi liquid damping due to non-critical scattering processes. On the other hand, in the strong coupling regime where $Gi$ is of order unity, we find that the quasiparticle damping due to critical pairing fluctuations is proportional to the temperature. Moreover, we show that in the vicinity of the critical temperature $T_c$ the electronic density of states exhibits a fluctuation-induced pseudogap. We also use functional renormalization group methods to derive and classify various types of processes induced by the pairing interaction in Fermi systems close to the superconducting instability.

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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