NCAFM2023 Programme Booklet

COLORING TRIANGLE LATTICE IN 2D SEMICONDUCTING Cr 2 Se 3

Sisheng Duan (Presenting) , Jian Gou, Jing-Yang You, Andrew T. S. Wee, Wei Chen* (Co-authors)

1 Department of Physics, National University of Singapore, 117551 Singapore Email: sisheng.duan@u.nus.edu

Obtaining emergent electronic excitations by designing the lattice geometry is a long-term pursuit in modern materials science. For example, the destructive interference of the electronic wave functions in specific lattice may give rise to the flat band. The coloring-triangle (CT) lattice was theoretically proposed to host kagome bands 1, 2 ; however, the experimental materials realization is limited 3 . In this work, we reported the molecular beam epitaxy growth of ferrimagnetic semiconducting Cr 2 Se 3 with atomic thickness, in which the topmost Se atoms form a CT lattice. Our scanning tunnelling spectroscopy and angle resolved photoemission spectroscopy investigations revealed the electronic excitations inherited from the Se CT lattice. Our detailed scanning tunnelling spectroscopy maps and non-contact atomic force microscopy investigations of the surface atomic and electronic structures allowed for visualizing the electronic patterning, which unveiled the mechanism of the CT lattice formation. The experimental synthesis of two-dimensional Cr 2 Se 3 consisting of CT lattice paves the way for investigating the interplay of two-dimensional magnetism and electron-electron correlation.

Fig. 1 (a, b) non-contact atomic force microscopy (a) and scanning tunnelling microscopy (b) images of Cr 2 Se 3 with CT lattice. References [1] Zhang, S.; Kang, M.; Huang, H.; Jiang, W.; Ni, X.; Kang, L.; Zhang, S.; Xu, H.; Liu, Z.; Liu, F. Physical Review B 2019 , 99, (10), 100404(R). [2] Kang, M.; Ye, L.; Fang, S.; You, J. S.; Levitan, A.; Han, M.; Facio, J. I.; Jozwiak, C.; Bostwick, A.; Rotenberg, E.; Chan, M. K.; McDonald, R. D.; Graf, D.; Kaznatcheev, K.; Vescovo, E.; Bell, D. C.; Kaxiras, E.; van den Brink, J.; Richter, M.; Prasad Ghimire, M.; Checkelsky, J. G.; Comin, R. Nat Mater 2019 , 19, 163–169. [3] Gao, Y.; Zhang, Y.-Y.; Sun, J.-T.; Zhang, L.; Zhang, S.; Du, S. Nano Research 2020 , 13, (6), 1571-1575.

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