Effect of chromium doping on superconductivity and charge density wave order in the kagome metal Cs(V1−xCrx)3Sb5

Abstract

The recently discovered kagome metal $A{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ ($A=\mathrm{K}$, Rb, Cs) with intertwined superconductivity and charge density wave (CDW) order has attracted considerable interest. Here we investigate the evolution of CDW and superconductivity in $\mathrm{Cs}{({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{3}{\mathrm{Sb}}_{5}$, where chromium substitution for vanadium introduces extra electron carriers. Our experiments reveal that the CDW order is gradually suppressed under chromium doping, which can be understood from the band structure modifications induced by electron doping. This highlights the importance of the van Hove singularities near the $M$ and $L$ points for CDW instability. The anomalous Hall effect that is coupled with CDW in ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ only appears in lightly doped $\mathrm{Cs}{({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{3}{\mathrm{Sb}}_{5}$ and vanishes at $x\ensuremath{\ge}0.06$ when the CDW order remains relatively strong. Unlike hole- and isovalent-doped $A{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$, where superconductivity is enhanced upon suppression of CDW, superconductivity is rapidly suppressed under chromium doping, pointing to a conventional $s$-wave pairing.