近日，中国科学院物理研究所的高鸿钧&陈辉及其研究团队取得一项新进展。经过不懈努力，他们揭示多波段CsV₃Sb₅衍生笼目超导体的可调谐涡旋束缚态。相关研究成果已于2024年1月28日在国际知名学术期刊《科学通报》上发表。

在这项研究中，研究人员利用低温扫描隧道显微镜/光谱法，观察了两种化学掺杂的笼目超导体Cs(V_1-xTr_x)₃Sb₅ (Tr=Ta或Ti)的可调谐涡旋束缚态(VBSs)。与原始的CsV₃Sb₅相比，CsV₃Sb₅衍生的笼目超导体表现出全能隙配对超导性，同时没有长程电荷有序。研究人员发现，在零能电导图上，涡旋晶格场驱动的连续重定向跃迁表明了多波段超导性的存在。

对于Ta掺杂的CsV₃Sb₅，其表现出了传统的Caroli-de Gennes-Matricon束缚态的十字形空间演化。而对于Ti掺杂的CsV₃Sb₅，它展现出一个尖锐的、非分裂零偏电导峰(ZBCP)，该峰在漩涡上持续了很长一段距离。非分裂ZBCP的空间演化对表面效应和外磁场有较强的抑制作用，但其表现与掺杂浓度有关。这一发现揭示了多波段化学掺杂CsV₃Sb₅体系中可调谐的VBSs，并为先前报道的笼目超导体表面非量子极限条件下的Y型ZBCP提供了新的见解。

据悉，涡旋和束缚态是理解超导体电子特性的重要手段。最近，在新型笼目超导体CsV₃Sb₅中观察到了表面依赖的涡旋核态。尽管其空间分布与超导狄拉克表面态产生的马约拉纳束缚态相似，但这种涡旋核态的起源仍是一个谜。

附：英文原文

Title: Tunable vortex bound states in multiband CsV₃Sb₅-derived kagome superconductors

Author: anonymous

Issue&Volume: 2024/01/28

Abstract: Vortices and bound states offer an effective means of comprehending the electronic properties of superconductors. Recently, surface-dependent vortex core states have been observed in the newly discovered kagome superconductors CsV₃Sb₅. Although the spatial distribution of the sharp zero energy conductance peak appears similar to Majorana bound states arising from the superconducting Dirac surface states, its origin remains elusive. In this study, we present observations of tunable vortex bound states (VBSs) in two chemically-doped kagome superconductors Cs(V_1-xTr_x)3Sb5 (Tr=Ta or Ti), using low-temperature scanning tunneling microscopy/spectroscopy. The CsV3Sb5-derived kagome superconductors exhibit full-gap-pairing superconductivity accompanied by the absence of long-range charge orders, in contrast to pristine CsV₃Sb₅. Zero-energy conductance maps demonstrate a field-driven continuous reorientation transition of the vortex lattice, suggesting multiband superconductivity. The Ta-doped CsV₃Sb₅ displays the conventional cross-shaped spatial evolution of Caroli-de Gennes-Matricon bound states, while the Ti-doped CsV₃Sb₅ exhibits a sharp, non-split zero-bias conductance peak (ZBCP) that persists over a long distance across the vortex. The spatial evolution of the non-split ZBCP is robust against surface effects and external magnetic field but is related to the doping concentrations. Our study reveals the tunable VBSs in multiband chemically-doped CsV₃Sb₅ system and offers fresh insights into previously reported Y-shaped ZBCP in a non-quantum-limit condition at the surface of kagome superconductor.

DOI: 10.1016/j.scib.2024.01.036

Source: https://www.sciencedirect.com/science/article/abs/pii/S209592732400063X