[2P01-53] Poster Presentation

[2P06] Submillimeter-scale growth of a single-crystal ternary boride and observation of the B-terminated metallic surface

*Xiaoni Zhang¹, Yuki Tsujikawa¹, Kazuki Yamaguchi¹, Masashige Miyamoto ¹, Masafumi Horio¹, Mei Yuan², Kenichi Ozawa³, Yasunobu Ando⁴, Kunio Yubuta⁵, Takahiro Kondo², Iwao Matsuda¹ (1. Institute for Solid States Physics (ISSP), the University of Tokyo, 2. Institute of Pure and Applied Sciences, University of Tsukuba, 3. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 4. The National Institute of Advanced Industrial Science and Technology (AIST), 5. Faculty of Engineering, Kyushu University)

2D boron networks in metal borides has been paid attention for exploring topology and functional atomic sheets. YCrB4, a XYB4-type boride (X=rare-earth, Y=transition metal), showcases pentagon-heptagon boron layers under non-symmorphic symmetry. YCrB4 crystal remains unexplored since samples are essentially polycrystalline that are embedded in the amorphous matrix. We grew YCrB4 crystals via arc-melting and post-annealing, producing 0.2~0.3 mm single-crystals confirmed by SEM-EDX and XRD. Mechanical peeling generated 2D flakes for surface analysis. Ar-sputtering and post-annealing unveiled a boron-terminated surface and its metallicity, observed through micro-focused photoelectron spectroscopy (micro-PES) at BL-28A, KEK-PF. The presentation thoroughly details YCrB4's bulk/surface electronic states with experimental and theoretical support. Insights into surface electronic structure arise from comparisons with crystal surface borophene layers.