DOE OSTI · 2587337
Frustrated electron hopping from the orbital configuration in a two-dimensional lattice
Abstract
Electron hopping on spatially periodic lattices gives rise to intriguing electronic behaviour. For example, hopping on the geometrically frustrated two-dimensional kagome, dice and Lieb lattices yields electronic band structures with both massless Dirac-like and perfectly dispersion-less, flat bands. As materials featuring the dice and Lieb lattice structures are scarce, an alternative approach proposes to leverage atomic orbitals to realize the characteristic electron hopping of geometrically frustrated lattices. This strategy promises to expand the list of candidate materials with frustrated electron hopping, but is yet to be shown in experiments. Here, in this study, we demonstrate frustrated hopping in the van der Waals intermetallic Pd 5 AlI 2 , emerging from the arrangement of atomic orbitals in a primitive square lattice. Using angle-resolved photoemission spectroscopy and quantum oscillation measurements, we reveal that the band structure of Pd 5 AlI 2 includes linear Dirac-like bands intersected at their crossing point by a locally flat band—an essential characteristic of frustrated hopping in Lieb and dice lattices. Moreover, this compound shows exceptional chemical stability, with its unusual bulk band structure and metallicity persisting in ambient conditions down to the monolayer limit. Hence, our results showcase a way to realize electronic structures characteristic of geometrically frustrated lattices in non-frustrated systems.
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Devarakonda, Aravind [Columbia Univ., New York, NY (United States)] (ORCID:0000000260957854), Koay, Christie S. [Columbia Univ., New York, NY (United States)] (ORCID:0000000271728328), Chica, Daniel G. [Columbia Univ., New York, NY (United States)], Thinel, Morgan [Columbia Univ., New York, NY (United States)] (ORCID:0000000214534594), Kundu, Asish K. [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000321991053), Lin, Zhi [Columbia Univ., New York, NY (United States); Boston Univ., MA (United States)] (ORCID:0000000178012755), Georgescu, Alexandru B. [Indiana Univ., Bloomington, IN (United States)] (ORCID:0000000231611491), Rossi, Sebastian [Columbia Univ., New York, NY (United States)] (ORCID:0009000813718501), Han, Sae Young [Columbia Univ., New York, NY (United States)], Ziebel, Michael E. [Columbia Univ., New York, NY (United States)] (ORCID:0000000318578292), Holbrook, Madisen A. [Columbia Univ., New York, NY (United States)] (ORCID:0000000220193562), Rajapitamahuni, Anil [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000330924258), Vescovo, Elio [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000303503861), Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119), Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105), Delor, Milan [Columbia Univ., New York, NY (United States)] (ORCID:0000000294809235), Zhu, Xiaoyang [Columbia Univ., New York, NY (United States)] (ORCID:0000000220908484), Pasupathy, Abhay N. [Columbia Univ., New York, NY (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000227440634), Queiroz, Raquel [Columbia Univ., New York, NY (United States)] (ORCID:0000000267148857), Dean, Cory R. [Columbia Univ., New York, NY (United States)] (ORCID:0000000329675960), Roy, Xavier [Columbia Univ., New York, NY (United States)] (ORCID:0000000288500725). 2025-08-07. Frustrated electron hopping from the orbital configuration in a two-dimensional lattice. https://doi.org/10.1038/s41567-025-02953-2
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