Complex magnetic and spatial symmetry breaking from correlations in kagome flat bands

Abstract

We present the mean-field phase diagram of electrons in a kagome flat band with repulsive interactions. In addition to flat-band ferromagnetism, the Hartree-Fock analysis yields cascades of unconventional magnetic orders driven by onsite repulsion as filling changes. These include a series of antiferromagnetic (AFM) spin-charge stripe orders, as well as an evolution from $120^{\circ }$AFM to intriguing noncoplanar spin orders with tetrahedral structures. We also map out the phase diagram under extended repulsion at half and empty fillings of the flat band. To examine the possibilities beyond the mean-field level, we conduct a projective symmetry group analysis and identify the feasible ${\mathbb{Z}}_2$ spin liquids and the magnetic orders derivable from them. The theoretical phase diagrams are compared with recent experiments on FeSn and FeGe, enabling a determination of the most likely magnetic instabilities in these and similar flat-band kagome materials.

7+20 pages, 3+11 figures. v2: Published version

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Cited by in corpus (10)

• Superconductivity in twisted WSe${}_2$ from topology-induced quantum fluctuations
• Persistent flat band splitting and strong selective band renormalization in a kagome magnet thin film
• Electron correlations in the kagome flat band metal $\mathrm{CsC}{\mathrm{r}}_3\mathrm{S}{\mathrm{b}}_5$
• Tunability of charge density wave in a magnetic kagome metal
• Vacancy-induced suppression of CDW order and its impact on magnetic order in kagome antiferromagnet FeGe
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• Floquet Flux Attachment in Cold Atomic Systems
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• Altermagnetism in an interacting model of Kagome materials
• Collinear ferromagnetism with reduced moment length in kagome magnet Nd3Ru4Al12