论文标题
奇数配对和反转对称性破坏排斥相互作用
Odd-frequency pairing and time-reversal symmetry breaking for repulsive interactions
论文作者
论文摘要
我们通过由哈伯德排斥，模仿筛选的库仑电位和动态的声子介导的吸引力来研究费米子的配对。对于这种相互作用，差距方程允许均匀和奇数的解决方案$δ_e$和$Δ_O$。我们表明，由于自我能源的过度关键配对，奇数配对不会在Eliashberg的近似中发展。当包括顶点校正时，配对交互变得更强，并且$Δ_O$可以发展。我们认为，即使在这种情况下，保持自我能源仍然是必须的，因为它取消了间隙方程中的热零件。我们进一步认为，$Δ_O$不受哈伯镇的拒绝影响，对于强烈的排斥，与减少的$δ_e$相当。由此产生的超导状态是叠加$δ_e\ pmiΔ_O$，尽管配对对称性是普通的$ s $ - 波。
We study the pairing of fermions by an interaction consisting of a Hubbard repulsion, mimicking a screened Coulomb potential, and a dynamical phonon-mediated attraction. For such interaction, the gap equation allows even- and odd-frequency solutions $Δ_e$ and $Δ_o$. We show that odd-frequency pairing does not develop within the Eliashberg approximation due to over-critical pair-breaking from the self-energy. When vertex corrections are included, the pairing interaction gets stronger, and $Δ_o$ can develop. We argue that even in this case keeping the self-energy is still a must as it cancels out the thermal piece in the gap equation. We further argue that $Δ_o$ is not affected by Hubbard repulsion and for strong repulsion is comparable to a reduced $Δ_e$. The resulting superconducting state is a superposition $Δ_e \pm i Δ_o$, which spontaneously breaks the time-reversal symmetry, despite that the pairing symmetry is an ordinary $s$-wave.
