Emergence of flat bands and ferromagnetic fluctuations via orbital-selective electron correlations in Mn-based kagome metal

Abstract

Kagome lattice has been actively studied for the possible realization of frustration-induced two-dimensional flat bands and a number of correlation-induced phases. Currently, the search for kagome systems with a nearly dispersionless flat band close to the Fermi level is ongoing. Here, by combining theoretical and experimental tools, we present Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$ as a novel realization of correlation-induced almost-flat bands in the kagome lattice in the vicinity of the Fermi level. Our magnetic susceptibility, ${}^{27}$Al nuclear magnetic resonance, transport, and optical conductivity measurements provide signatures of a correlated metallic phase with tantalizing ferromagnetic instability. Our dynamical mean-field calculations suggest that such ferromagnetic instability observed originates from the formation of nearly flat dispersions close to the Fermi level, where electron correlations induce strong orbital-selective renormalization and manifestation of the kagome-frustrated bands. In addition, a significant negative magnetoresistance signal is observed, which can be attributed to the suppression of flat-band-induced ferromagnetic fluctuation, which further supports the formation of flat bands in this compound. These findings broaden a new prospect to harness correlated topological phases via multiorbital correlations in 3$d$-based kagome systems.

14 pages, 7 figures

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Cited by in corpus (9)

• Spin Excitations and Flat Electronic Bands in a Cr-based Kagome Superconductor
• LiV2O4: Hund-Assisted Orbital-Selective Mottness
• Experimental realization of dice-lattice flat band at the Fermi level in layered electride YCl
• Hund flat band in a frustrated spinel oxide
• Observation of Resonance of Kagome Flat Band Doublet
• Coexisting Kagome and Heavy Fermion Flat Bands in YbCr${}_6$Ge${}_6$
• Exploring strong electronic correlations in the breathing kagome metal Fe${}_3$Sn
• Slow ferromagnetic fluctuations in the kagome metal Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$ revealed by ${}^{27}$Al NMR
• Emergent Spin-Singlet Pairing in the Frustrated Kagome Metal Sc${}_3$Mn${}_3$Al${}_7$Si${}_5$