Topological pair density waves in kagome superconductors

Abstract

In pair density waves, the superconducting order modulates periodically in real space, breaking lattice translational symmetry. When a phase winding exists between pair density waves, time-reversal symmetry can also be broken, leading to topological pair density waves (TPDWs). These states illustrate an intriguing synthesis between unconventional superconductivity and topological quantum matter. Although experimental identification of TPDWs is elusive, kagome superconductors provide a useful platform to explore these states. In this Perspective, we review the experimental progress in realizing TPDWs in kagome lattices, discuss the theoretical implications and suggest direction for future work. Topological pair density waves offer an insight into the interplay among finite-momentum pairing, topological matter and chiral superconductivity. This Perspective explores signatures of these states in kagome superconductors.