Theory of tunneling anomalies in superconductors above the paramagnetic limit
Theory of tunneling anomalies in superconductors above the paramagnetic limit
复制标题
超过顺磁极限的超导体中的隧道异常理论
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
B. Altshuler
中科院分区：
文献类型：
--
作者：
H. Kee;I. Aleiner;B. Altshuler
研究了由塞曼分裂成顺磁相驱动的超导系统的隧穿态密度。结果表明，即使BCS能隙消失，超导涨落也会在能量范围内产生很强的DoS奇异性，对于沿磁场极化的电子，在能量为-E^*，而在相反极化的能量附近，则为-E^*。这个奇点$E^*=情形{1}{2}(E_Z+SQRT{E_Z^2-Delta^2})$(其中$Delta$是$E_Z=0$处的BCS间隙)的位置是普适的。我们解析地找到了系统不同维度下的DO形状。对于超小颗粒，奇点具有硬间隙的形状，而在更高的维度中，它看起来是一个重要的、尽管有限的凹陷。自旋-轨道散射和轨道磁场抑制了奇异性。我们的结果与最近在超导薄膜中的实验定性一致。
We study the tunneling density of states (DoS) in the superconducting systems driven by Zeeman splitting $E_Z$ into the paramagnetic phase. We show that, even though the BCS gap disappears, superconducting fluctuations cause a strong DoS singularity in the vicinity of energies $-E^*$ for electrons polarized along the magnetic field and $E^*$ for the opposite polarization. The position of this singularity $E^*=case{1}{2}(E_Z + sqrt{E_Z^2- Delta^2})$ (where $Delta$ is BCS gap at $E_Z=0$) is universal. We found analytically the shape of the DoS for different dimensionality of the system. For ultra-small grains the singularity has the shape of the hard gap, while in higher dimensions it appears as a significant though finite dip. The spin-orbit scattering, and the orbital magnetic field suppress the singularity. Our results are qualitatively consistent with recent experiments in superconducting films.