Temperature-driven reorganization of electronic order in CsV$_3$Sb$_5$

TL;DR

This study reveals a temperature-induced reorganization of the electronic order in CsV$_3$Sb$_5$, showing a transition from a 2x2x2 to a 2x2x4 superstructure that affects its transport properties and symmetry.

Contribution

It uncovers a novel temperature-driven electronic order transition in CsV$_3$Sb$_5$, linking structural changes to transport anomalies and symmetry breaking.

Findings

Electronic order transitions from 2x2x2 to 2x2x4 superstructure with temperature.

Electronic order influences transport properties via Berry-curvature effects.

Bulk electronic order breaks the lattice's sixfold rotational symmetry.

Abstract

We report a temperature dependent x-ray diffraction study of the electronic ordering instabilities in the kagome material CsV$_3$Sb$_5$. Our measurements between 10 K and 120 K reveal an unexpected reorganization of the three-dimensional electronic order in the bulk of CsV$_3$Sb$_5$: At 10 K, a 2x2x2 superstructure modulation due to electronic order is observed, which upon warming changes to a 2x2x4 superstructure at 60 K. The electronic order-order transition discovered here involves a change in the stacking of electronically ordered V$_3$Sb$_5$-layers and agrees perfectly with anomalies previously observed in magneto-transport measurements. This implies that the temperature dependent three-dimensional electronic order plays a decisive role for transport properties, which are related to the Berry-curvature of the V-bands. Our data also show that the bulk electronic order in CsV$_3$Sb$_5$ breaks the 6-fold rotational symmetry of the underlying $P6/mmm$ lattice structure.