Ganguli Somesh Chandra, Vaňo Viliam, Kezilebieke Shawulienu, Lado Jose L, Liljeroth Peter
Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland.
Nano Lett. 2022 Mar 9;22(5):1845-1850. doi: 10.1021/acs.nanolett.1c03491. Epub 2022 Feb 15.
Transition metal dichalcogenides (TMDC) are a rich family of two-dimensional materials displaying a multitude of different quantum ground states. In particular, d TMDCs are paradigmatic materials hosting a variety of symmetry broken states, including charge density waves, superconductivity, and magnetism. Among this family, NbSe is one of the best-studied superconducting materials down to the monolayer limit. Despite its superconducting nature, a variety of results point toward strong electronic repulsions in NbSe. Here, we control the strength of the interactions experimentally via quantum confinement and use low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) to demonstrate that NbSe is in close proximity to a correlated insulating state. This reveals the coexistence of competing interactions in NbSe, creating a transition from a superconducting to an insulating quantum correlated state by confinement-controlled interactions. Our results demonstrate the dramatic role of interactions in NbSe, establishing NbSe as a correlated superconductor with competing interactions.
过渡金属二硫属化物（TMDC）是一类丰富的二维材料，展现出多种不同的量子基态。特别是，d族TMDC是典型材料，具有多种对称性破缺态，包括电荷密度波、超导性和磁性。在这个家族中，NbSe是研究得最为深入的超导材料之一，直至单层极限。尽管其具有超导性质，但多种结果表明NbSe中存在强烈的电子排斥作用。在此，我们通过量子限域实验控制相互作用的强度，并利用低温扫描隧道显微镜（STM）和光谱学（STS）证明NbSe非常接近一种关联绝缘态。这揭示了NbSe中竞争相互作用的共存，通过限域控制的相互作用实现从超导到绝缘量子关联态的转变。我们的结果证明了相互作用在NbSe中的显著作用，确立了NbSe作为具有竞争相互作用的关联超导体的地位。
