Double-dome superconductivity under pressure in the V-based Kagome metals AV3Sb5 (A = Rb and K)

TL;DR

This study reveals that V-based Kagome metals AV3Sb5 exhibit double-dome superconductivity under pressure, with varying critical temperatures influenced by the ionic radius of the intercalated alkali metal, highlighting a common feature in these materials.

Contribution

First high-pressure measurements showing double-dome superconductivity in RbV3Sb5 and KV3Sb5, expanding understanding of pressure effects in V-based Kagome superconductors.

Findings

RbV3Sb5's Tc peaks at 4.15 K under 0.38 GPa

KV3Sb5 shows lower Tc maxima and faster decline in second dome

Pressure phase diagram correlates with ionic radius of alkali metals

Abstract

We present high-pressure electrical transport measurements on the newly discovered V-based superconductors $A$V$_3$Sb$_5$ ($A$ = Rb and K), which have an ideal Kagome lattice of vanadium. Two superconducting domes under pressure are observed in both compounds, as previously observed in their sister compound CsV$_3$Sb$_5$. For RbV$_3$Sb$_5$, the $T_c$ increases from 0.93 K at ambient pressure to the maximum of 4.15 K at 0.38 GPa in the first dome. The second superconducting dome has the highest $T_c$ of 1.57 K at 28.8 GPa. KV$_3$Sb$_5$ displays a similar double-dome phase diagram, however, its two maximum $T_c$s are lower, and the $T_c$ drops faster in the second dome than RbV$_3$Sb$_5$. An integrated temperature-pressure phase diagram of $A$V$_3$Sb$_5$ ($A$ = Cs, Rb and K) is constructed, showing that the ionic radius of the intercalated alkali-metal atoms has a significant effect. Our work demonstrates that double-dome superconductivity under pressure is a common feature of these V-based Kagome metals.