论文标题
一个奇怪的库珀对磁性杂质
An odd-frequency Cooper pair around a magnetic impurity
论文作者
论文摘要
Yu-Shiba-Rusinov（YSR）状态在嵌入超导体中的磁原子处是二粒子的结合状态。我们讨论了为什么YSR状态在超导间隙以下的能量以及两对电势会改变磁原子处的符号。尽管自1960年代以来，超导体中的磁原子被认为是一对破碎器，但我们提出了一种替代的物理图片来解释这些原因。我们表明，磁性原子将旋转的S-Wave Cooper对转换为奇数频对，而不是打破它。奇数配对相关性总是与差距下方的准粒子状态共存。 YSR状态是这种子隙准粒子状态的一个例子。奇数对的顺磁特性解释了在磁原子上对这对电位的符号变化，以及在存在许多磁性杂质的情况下，超导过渡温度的降低。
The Yu-Shiba-Rusinov (YSR) state appears as a bound state of a quasiparticle at a magnetic atom embedded in a superconductor. We discuss why the YSR state has energy below the superconducting gap and why the pair potential changes the sign at the magnetic atom. Although a magnetic atom in a superconductor has been considered as a pair breaker since 1960s, we propose an alternative physical picture to explain these reasons. We show that a magnetic atom converts a spin-singlet s-wave Cooper pair into an odd-frequency pair rather than breaking it. The odd-frequency pairing correlations always coexist with the quasiparticle states below the gap. The YSR state is an example of such a subgap quasiparticle state. The paramagnetic property of an odd-frequency pair explains the sign change of the pair potential at a magnetic atom and the decrease of superconducting transition temperature in the presence of many magnetic impurities.
