Superconductivity near a nematic quantum critical point: Interplay between hot and lukewarm regions
Superconductivity near a nematic quantum critical point: Interplay between hot and lukewarm regions
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DOI：
10.1103/physrevb.98.220501
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发表时间：
2018-12-04
影响因子：
3.7
通讯作者：
Chubukov, Andrey
中科院分区：
文献类型：
--
作者：
Klein, Avraham;Chubukov, Andrey
我们提出了金属超导相变的强耦合动力学理论，它位于Q=0向列相的量子临界点附近。我们使用费米子-玻色子模型，将有效玻色子-费米子耦合比和费米能量视为一个小参数。我们从解析和数值两方面求解了线性化的Eliashberg方程。我们的解决方案既考虑了类似于λk(F)的小动量转移时的强烈波动，也考虑了大动量转移时的较弱波动。强烈的涨落决定了T-c，对于S和d波配对，T-c都是E-2(F)量级的。较弱的涨落决定了超导序参数F(theta(K))沿费米面的角结构，区分在热区和温区之间。在热区，F(theta(K))最大且近似不变。在宽度类似于lambda(1/3)的热区之外，F(theta(K))下降了一个因数lambda(4/3)。S波和d波态不简并，但与波长(2)相似的相对差(T-c(S)-T-c(D))/T-c(S)很小。
We present a strong-coupling dynamical theory of the superconducting transition in a metal near a quantum-critical point toward Q = 0 nematic order. We use a fermion-boson model, in which we treat the ratio of effective boson-fermion coupling and the Fermi energy as a small parameter lambda. We solve, both analytically and numerically, the linearized Eliashberg equation. Our solution takes into account both strong fluctuations at small momentum transfers similar to lambda k(F) and weaker fluctuations at large momentum transfers. The strong fluctuations determine T-c which is of order lambda E-2(F) for both s- and d-wave pairing. The weaker fluctuations determine the angular structure of the superconducting order parameter F(theta(k)) along the Fermi surface, separating between hot and lukewarm regions. In the hot regions F(theta(k)) is largest and approximately constant. Beyond the hot region, whose width is theta(h) similar to lambda(1/3), F(theta(k)) drops by a factor lambda(4/3). The s- and d-wave states are not degenerate but the relative difference (T-c(s) - T-c(d))/T-c(s) similar to lambda(2) is small.