Frustrated metals: Understanding correlated phenomenon using compact molecular orbitals.

Flat bands can develop from geometrically frustrated lattices as a consequence of destructive interference, leading to enhanced correlation effects. This is seen in kagome metal and its variants with active flat bands[1-4]. We consider one such material Ni3In, a bilayer kagome system hosting a flat band near Fermi level, with non-Fermi liquid signatures seen experimentally[2,5]. Under compact molecular orbital description[6,7], this system reduces to an effective Anderson lattice model, indicating Kondo correlations. We investigate the structure of the compact molecular orbitals, their implications for correlation properties, and their experimental signatures in a number of spectroscopies. Broad implications of our results will be discussed.

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[2] L. Ye et al., Nature Physics 20, 610 (2024).

[3] S. A. Ekahana et al., Nature 627, 67 (2024).

[4] Y. Liu et al., Nature 632, 1032 (2024).

[5] M. Mahankali et al, arXiv:2503.09706

[6] J. C. Souza et al, arXiv:2503.09704

[7] L. Chen, et al., arXiv:2307.09431; L. Chen et al. Nat. Commun. 15, 5242 (2024); H. Hu et al., Sci. Adv. 9, eadg0028 (2023).