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arXiv 2103.14656cond-mat.supr-con
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超导体中自旋之间的调谐相互作用

Tuning interactions between spins in a superconductor

Hao Ding, Yuwen Hu, Mallika T. Randeria, Silas Hoffman, Oindrila Deb, Jelena Klinovaja, Daniel Loss, Ali Yazdani

摘要:

新的多体和拓扑电子相可以在耦合到超导体的相互作用自旋组件中创建,例如在其末端具有马约拉纳零模式(MZM)的一维拓扑超导体。理解和控制自旋之间的相互作用和它们在超导体中诱导的带隙Yu-Shiba-Rusinov(YSR)态的新兴能带结构是工程设计此类相位的基础。在这里,通过精确地定位磁性吸附原子与扫描隧道显微镜(STM),我们证明了自旋之间的交换相互作用的可调谐性和精确控制的杂交的YSR状态,他们诱导的铋(Bi)薄膜的表面上,这是超导的邻近效应。在这个平台中,根据自旋的分离,Ruderman-Kittel-Kasuya-Yosida(RKKY)相互作用,自旋轨道耦合和表面磁各向异性之间的相互作用稳定了不同类型的自旋对齐。使用高分辨率STM光谱在毫开尔文温度下,我们探测这些自旋排列通过监测自旋诱导的YSR状态和它们的能量分裂。这样的测量也揭示了一个量子相变之间的基态与不同的电子数宇称的一对自旋在超导体调谐由他们的分离。在更大的组件上的实验表明,自旋-自旋相互作用可以在长距离的超导体中进行调节。我们的研究结果表明,在这个平台上控制杂化的YSR状态提供了工程的能带结构,这样的国家创造拓扑相位的可能性。

英文摘要:

Novel many-body and topological electronic phases can be created in assemblies of interacting spins coupled to a superconductor, such as one-dimensional topological superconductors with Majorana zero modes (MZMs) at their ends. Understanding and controlling interactions between spins and the emergent band structure of the in-gap Yu-Shiba-Rusinov (YSR) states they induce in a superconductor are fundamental for engineering such phases. Here, by precisely positioning magnetic adatoms with a scanning tunneling microscope (STM), we demonstrate both the tunability of exchange interaction between spins and precise control of the hybridization of YSR states they induce on the surface of a bismuth (Bi) thin film that is made superconducting with the proximity effect. In this platform, depending on the separation of spins, the interplay between Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, spin-orbit coupling, and surface magnetic anisotropy stabilizes different types of spin alignments. Using high-resolution STM spectroscopy at millikelvin temperatures, we probe these spin alignments through monitoring the spin-induced YSR states and their energy splitting. Such measurements also reveal a quantum phase transition between the ground states with different electron number parity for a pair of spins in a superconductor tuned by their separation. Experiments on larger assemblies show that spin-spin interactions can be mediated in a superconductor over long distances. Our results show that controlling hybridization of the YSR states in this platform provides the possibility of engineering the band structure of such states for creating topological phases.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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