Role of Sb in the superconducting kagome metal CsV$_3$Sb$_5$ revealed by its anisotropic compression

TL;DR

This study reveals that Sb atoms play a crucial role in the pressure-induced suppression of charge-density-wave order and the evolution of superconductivity in CsV$_3$Sb$_5$, highlighting the importance of Sb in the material's electronic structure.

Contribution

It demonstrates that Sb atoms are key to the stabilization of CDW and Fermi surface changes, challenging previous focus on vanadium kagome bands for superconductivity tuning.

Findings

Anisotropic compression up to 5 GPa affects Cs-Sb distances and suppresses Cs rattling.

Disappearance of CDW at 2 GPa occurs despite minor changes in vanadium electronic structure.

Sb bands undergo major reconstruction due to interlayer Sb-Sb bond formation.

Abstract

Pressure evolution of the superconducting kagome metal CsV$_3$Sb$_5$ is studied with single-crystal x-ray diffraction and density-functional band-structure calculations. A highly anisotropic compression observed up to 5 GPa is ascribed to the fast shrinkage of the Cs-Sb distances and suppression of Cs rattling motion. This prevents Sb displacements required to stabilize the three-dimensional charge-density-wave (CDW) order and elucidates the disappearance of the CDW already at 2 GPa despite only minor changes in the electronic structure of the normal state. At higher pressures, vanadium bands still change only marginally, whereas antimony bands undergo a major reconstruction caused by the gradual formation of the interlayer Sb-Sb bonds. Our results exclude pressure tuning of vanadium kagome bands as the main mechanism for the non-trivial evolution of superconductivity in real-world kagome metals. Concurrently, we establish the central role of Sb atoms in the stabilization of a three-dimensional CDW and Fermi surface reconstruction.