[3Ia01-06] Two-Dimensional (2D) Materials

[3Ia06(2023女子大学院生優秀賞)] Observation of unexpected 2D copper boride at a surface and exploration of exotic states in the internal 1D boron

*Yuki Tsujikawa^1,2, Iwao Matsuda^1,2 (1. Graduate School of science, The University of Tokyo, 2. The Institute for Solid State Physics, The University of Tokyo)

Surfaces have been a critical playground for new materials to spread our understanding of physics and chemistry. Here we introduce the structural and chemical analyses of a novel copper boride layer on Cu(111). By the diffraction method, we determined the structure to be a periodic array of boron and Cu atom chains having a zig-zag structure. The photoemission result suggested negatively charged boron atoms and hence electron donation from Cu atoms to boron. By comparing the experimental results with first-principles calculations, we found similarity between these boron chains and already known carbon chains such as cumulene, and proposes that the π-type bonding state is the reason for their stability. We believe our comprehensive work would provide a new aspect of surface science and opened a new boron science in 1D.