Topological quantum materials: kagome, chiral, and square-net frameworks

Abstract: Topological quantum materials have emerged as a frontier in condensed matter physics as well as in materials science, with intriguing electronic states that are robust to perturbations. Among the diverse structural motifs, kagome, chiral, and square-net structures offer a wide range of topological phases and physical phenomena. These include Dirac and Weyl fermions, nodal-line semimetals, flat bands, van Hove singularities, charge density waves, superconductivity, nontrivial Berry phase, nonlinear electrical and thermal transports. This review explores the distinct roles of geometry, symmetry, spin-orbit coupling, and electron correlations in these three classes of materials. It also highlights how their crystallographic features give rise to unique electronic band structures, topologically protected states and different physical properties, which require high-quality-single crystals. The present discussion comprises recent experimental discoveries and identification of the synthesis routes of key materials within each framework. Finally, the review outlines the current challenges and future directions in the design and exploration of topological quantum materials.