Coexistence of two intertwined charge density waves in a kagome system

Materials with a kagome lattice structure display a wealth of intriguing magnetic properties due to their geometric frustration and intrinsically flat band structure. Recently, topological and superconducting states have also been observed in kagome systems. The kagome lattice may also host a breathing mode that leads to charge density wave (CDW) states, if there is strong electron-phonon coupling, electron-electron interaction, or external excitation of the material. This breathing mode can give rise to candidate distortions such as the star of David (SoD) or its inverse structure [trihexagonal (TrH)]. To date, in most materials, only a single type of distortion has been observed. Here, we present angle-resolved photoemission spectroscopy measurements on the kagome superconductor CsV3Sb5 at multiple temperatures and photon energies to reveal the nature of the CDW in this material. It is shown that CsV3Sb5 displays two intertwined CDW orders corresponding to the SoD and TrH distortions. These two distinct types of distortions are stacked along the c direction to form a three-dimensional CDW order where the two 2-fold CDWs are phase shifted along the c axis. The presented results provide not only key insights into the nature of the unconventional CDW order in CsV3Sb5, but also an important reference for further studies on the relationship between the CDW and superconducting order.

Automated summary

Materials with a kagome lattice structure exhibit intriguing magnetic properties and have recently been found to possess topological and superconducting states. This study focuses on CsV3Sb5, a kagome superconductor, and uses angle-resolved photoemission spectroscopy to reveal the nature of its charge density wave (CDW). The results show that CsV3Sb5 displays intertwined CDW orders corresponding to two distinct types of distortions, the star of David and trihexagonal distortions.