Topological kagome magnets and superconductors

TL;DR

This review discusses the unique electronic properties of kagome lattices, their realization in magnetic and superconducting materials, and the emergent topological and correlated phenomena that advance the understanding of quantum matter.

Contribution

It provides a comprehensive overview of recent experimental and theoretical progress in topological kagome magnets and superconductors, connecting fundamental concepts to novel quantum states.

Findings

Discovery of Chern and Weyl topological magnetism in kagome materials.

Observation of flat-band correlated phenomena such as magnetism and superconductivity.

Identification of unconventional charge-density waves and superconducting states in kagome systems.

Abstract

A kagome lattice naturally features Dirac fermions, flat bands and van Hove singularities in its electronic structure. The Dirac fermions encode topology, flat bands favour correlated phenomena such as magnetism, and van Hove singularities can lead to instabilities towards long-range many-body orders, altogether allowing for the realization and discovery of a series of topological kagome magnets and superconductors with exotic properties. Recent progress in exploring kagome materials has revealed rich emergent phenomena resulting from the quantum interactions between geometry, topology, spin and correlation. Here we review these key developments in this field, starting from the fundamental concepts of a kagome lattice, to the realizations of Chern and Weyl topological magnetism, to various flat-band many-body correlations, and then to the puzzles of unconventional charge-density waves and superconductivity. We highlight the connection between theoretical ideas and experimental observations, and the bond between quantum interactions within kagome magnets and kagome superconductors, as well as their relation to the concepts in topological insulators, topological superconductors, Weyl semimetals and high-temperature superconductors. These developments broadly bridge topological quantum physics and correlated many-body physics in a wide range of bulk materials and substantially advance the frontier of topological quantum matter.