Interplay between charge order and superconductivity in the kagome metal KV$_3$Sb$_5$

TL;DR

This study investigates how hydrostatic pressure influences charge order and superconductivity in the kagome metal KV$_3$Sb$_5$, revealing two superconducting domes and their relation to charge order suppression.

Contribution

It provides the first detailed pressure-dependent phase diagram of KV$_3$Sb$_5$, showing the emergence of a second superconducting dome linked to a high-pressure phase.

Findings

Superconducting transition temperature increases with pressure up to 3.1 K.

Charge order disappears around 0.5 GPa, coinciding with the first superconducting dome.

A second superconducting dome appears above 10 GPa, associated with a high-pressure phase.

Abstract

The kagome metal KV$_3$Sb$_5$ hosts charge order, topologically nontrivial Dirac band crossings, and a superconducting ground state with unconventional characteristics, providing an ideal platform to investigate the interplay between different electronic states on the kagome lattice. Here we study the evolution of charge order and superconductivity in KV$_3$Sb$_5$ under hydrostatic pressure using electrical resistivity measurements. With the application of pressure, the superconducting transition temperature $T_{\rm c}=0.9$ K under ambient pressure quickly increases to 3.1 K at $p=0.4$ GPa, as charge order progressively weakens. Upon further increasing pressure, signatures of charge order disappears at $p_{\rm c1}\approx0.5$ GPa and $T_{\rm c}$ is gradually suppressed, forming a superconducting dome that terminates at $p\approx10$ GPa. Beyond $p\approx10$ GPa, a second superconducting dome emerges with maximum $T_{\rm c}\approx1.0$ K at $p_{\rm c2}\approx22$ GPa, which becomes fully suppressed at $p\approx28$ GPa. The suppression of superconductivity for the second superconducting dome is associated with the appearance of a unique high-pressure phase , possibly a distinct charge order.