Imaging Quantum Interference in a Monolayer Kitaev Quantum Spin Liquid Candidate

作者：Y. Kohsaka, Satoru Akutagawa, Shinichiro Omachi, Y. Iwamichi, Takahito Ono, Isao Tanaka, Satoshi Tateishi, H. Murayama, S. Suetsugu, Kazuhito Hashimoto, T. Shibauchi, Masahiro Takahashi, S. A. Nikolaev, Takeshi Mizushima, Satoshi Fujimoto, Takahito Terashima, Tomoya Asaba, Y. Kasahara, Yuji Matsuda · 发表于：Physical Review X · 年份：2024 · DOI：10.1103/physrevx.14.041026 · 被引用次数：6 · 研究领域：Advanced Condensed Matter Physics、Perovskite Materials and Applications、Electronic and Structural Properties of Oxides

Single atomic defects are prominent windows to look into host quantum states because collective responses from the host states emerge as localized states around the defects. Friedel oscillations and Kondo clouds in Fermi liquids are quintessential examples. However, the situation is quite different for quantum spin liquid (QSL), an exotic state of matter with fractionalized quasiparticles and topological order arising from a profound impact of quantum entanglement. Elucidating the underlying local electronic property has been challenging due to the charge neutrality of fractionalized quasiparticles and the insulating nature of QSLs. Here, using spectroscopic-imaging scanning tunneling microscopy, we report atomically resolved images of monolayer α − RuCl 3 , the most promising Kitaev QSL candidate, on metallic substrates. We find quantum interference in the insulator manifesting as incommensurate and decaying spatial oscillations of the local density of states around defects with a characteristic bias dependence. The oscillation differs from any known spatial structures in its nature and does not exist in other Mott insulators, implying it is an exotic oscillation involved with excitations unique to α − RuCl 3 . Numerical simulations suggest that the observed oscillation can be reproduced by assuming that itinerant Majorana fermions of Kitaev QSL are scattered across the Majorana Fermi surface. The oscillation provides a...