论文标题
Zeeman对Yu-Shiba-Rusinov的影响
Zeeman effects on Yu-Shiba-Rusinov states
论文作者
论文摘要
当杂质自旋与巡回准颗粒的旋转之间的交换相互作用很强或足够弱时，超导体中磁杂质的基态分别为筛选或游离旋转。在这两种情况下，最低的激发态都是超导间隙内的结合状态，称为Yu-Shiba-Rusinov（YSR）状态。 YSR状态是空间局部的，能量分离的，并且完全自旋偏振，从而导致了诸如功能扫描探针之类的应用。尽管任何应用都需要确定杂质旋转是筛选还是免费的，但合适的实验技术是难以捉摸的。在这里，我们展示了一种使用Zeeman效应来确定杂质基态的明确方法。我们对Cu（111）表面和由单个磁性Fe原子装饰的超导式NB尖端进行了超低温度扫描隧穿光谱。根据FE吸附物的条件，频谱中的YSR峰分裂或磁场中的移位，表示分别筛选了Fe自旋或游离。我们的观察结果为磁性和超导性之间的竞争提供了新的见解，并构成了YSR国家应用的基础。
When the exchange interaction between the impurity spin and the spins of itinerant quasiparticles are strong or weak enough, the ground states for a magnetic impurity in a superconductor are the screened or free spins, respectively. In both cases, the lowest excited state is a bound state within the superconducting gap, known as the Yu-Shiba-Rusinov (YSR) state. The YSR state is spatially localized, energetically isolated, and fully spin-polarized, leading to applications such as functional scanning probes. While any application demands identifying whether the impurity spin is screened or free, a suitable experimental technique has been elusive. Here we demonstrate an unambiguous way to determine the impurity ground state using the Zeeman effect. We performed ultra-low temperature scanning tunneling spectroscopy of junctions formed between a Cu(111) surface and superconducting Nb tips decorated by single magnetic Fe atoms. Depending on the condition of the Fe adsorbate, the YSR peak in the spectrum either splits or shifts in a magnetic field, signifying that the Fe spin is screened or free, respectively. Our observations provide renewed insights into the competition between magnetism and superconductivity and constitute a basis for the applications of the YSR state.
