Quantum states and intertwining phases in kagome materials

By Yaoji Wang, Heng Wu, G. McCandless, J. Chan, Mazhar N. Ali. Nature Reviews Physics, 2023

173 citations recorded by the source corpus.

Kagome materials provide great opportunities for investigating diverse quantum phenomena based on the interplay of topology, electron correlation and magnetism. This Review describes the fundamental physics and properties of contemporary kagome materials and their open questions and future research directions. The kagome lattice is formed by corner-sharing triangles, which can host Dirac points, van Hove singularities (vHSs) and flat bands. The high Fermi surface instability around the vHSs and flat bands can give rise to various physical properties that can be entangled, including superconductivity, charge or spin orders, and complex magnetism. Charge density wave (CDW) states induced by the vHSs mostly appear in kagome materials with non-magnetic or weak magnetism, but are rare in kagome magnets. The relationship between magnetism and CDWs is not yet fully understood. Diverse magnetic properties appearing in kagome magnets are influenced by the interlayer and intralayer magnetic interaction of kagome lattices and other sublattices. A Mott-insulating state was observed in the symmetry breaking, breathing kagome insulators with flat bands. Strong correlation physics related to flat bands can be studied in kagome system. In solid materials, non-trivial topological states, electron correlations and magnetism are central ingredients for realizing quantum properties, including unconventional superconductivity, charge and spin density waves and quantum spin liquids. The kagome lattice, made up of corner-sharing triangles, can host these three ingredients simultaneously and has proved to be a fertile platform for studying diverse quantum phenomena including those stemming from the interplay of these ingredients. This Review introduces the fundamental properties of the kagome lattice and discusses the complex phenomena observed in several materials systems, including the intertwining of charge order and superconductivity in some kagome metals, the modulation of magnetism and topology in some kagome magnets, and the combination of symmetry breaking and Mott physics in ‘breathing’ kagome insulators. The Review also highlights open questions in the field and future research directions in kagome systems.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/6e3e0f974dd6153db6da63cb142964c1c9074d03