Presentation Information
[3C11【会誌賞】]Formation and electronic structure of boron–metal composite atomic chains on a 2D surface
*Yuki Tsujikawa1, Xiaoni Zhang2, Masafumi Horio2, Fumio Komori2, Takeru Nakashima3, Yasunobu Ando3, Takahiro Kondo4,5, Iwao Matsuda2,6 (1. Faculty of Science and Technology, Keio University, 2. Institute for Solid State Physics, The University of Tokyo, 3. Institute of Integrated Research, Science Tokyo, 4. Department of Materials Science, Institute of Pure and Applied Sciences, University of Tsukuba, 5. Tsukuba Research Center for Energy Materials Science, Institute of Pure and Applied Sciences and R&D Center for Zero CO2 Emission Functional Materials, University of Tsukuba, 6. Trans-scale Quantum Science Institute, The University of Tokyo)
Boron (B) forms diverse structures due to its unique bonding characteristics, even in low-dimensional materials such as borophene, a single-layer boron sheet, and other two-dimensional boron compounds. These materials exhibit a range of 2D structures and novel properties, yet many remain experimentally unresolved due to challenges in structural analysis. Using positron diffraction and photoelectron spectroscopy, we identified a boron-covered Cu(111) surface to be a B–Cu compound, which was previously misidentified as borophene. This unexpected surface structure consists of alternating zigzag boron and copper atomic chains. First-principles calculations reproduced the observed structure and revealed that electron doping from copper atoms stabilizes the one-dimensional boron chains through π-type bonding. This finding led to the proposal of the "Bumulene" model, inspired by cumulene molecules. We further investigated substrate-induced electronic state variations using both theoretical calculations and ARPES. Similar B–Cu surface structures were also observed on Cu(110) and Cu(100), marking the emergence of this new surface materials.