Pressure-Induced Dome-Shaped Superconductivity in Topological Dirac Semimetal KZnBi

The three-dimensional topological Dirac semimetal KZnBi hosts symmetry-protected Dirac fermions and exhibits superconductivity, providing an attractive system for studying the interplay between topological states and superconductivity. We report high-pressure measurements of the temperature-dependent resistance, transverse magnetoresistance, and Hall resistance of KZnBi up to 36 GPa. The superconducting transition temperature <inline-formula><tex-math>${\mathit{T}}_{\mathit{c}}^{\text{onse}\text{t}}\mathit{ }\end{equation}$</tex-math><mml:math xmlns="http://www.w3.org/1998/Math/MathML" id="Mml1"><mml:msubsup><mml:mrow><mml:mi mathvariant="italic">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">c</mml:mi></mml:mrow><mml:mrow><mml:mtext>onse</mml:mtext><mml:mtext>t</mml:mtext></mml:mrow></mml:msubsup><mml:mi mathvariant="italic"> </mml:mi></mml:math></inline-formula>shows a nonmonotonic pressure dependence. The first dome begins to form at around 0.9 GPa, with <inline-formula><tex-math>${\mathit{T}}_{\mathit{c}}^{\text{onset}}\end{equation}$</tex-math><mml:math xmlns="http://www.w3.org/1998/Math/MathML" id="Mml2"><mml:msubsup><mml:mrow><mml:mi mathvariant="italic">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">c</mml:mi></mml:mrow><mml:mrow><mml:mtext>onset</mml:mtext></mml:mrow></mml:msubsup></mml:math></inline-formula> reaching its maximum at about 1.6 GPa before decreasing to a minimum near 4.0 GPa. Upon further compression, <inline-formula><tex-math>${\mathit{T}}_{\mathit{c}}^{\text{onset}}\end{equation}$</tex-math><mml:math xmlns="http://www.w3.org/1998/Math/MathML" id="Mml3"><mml:msubsup><mml:mrow><mml:mi mathvariant="italic">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">c</mml:mi></mml:mrow><mml:mrow><mml:mtext>onset</mml:mtext></mml:mrow></mml:msubsup></mml:math></inline-formula> rises again and forms a second dome with a maximum of approximately 4.2 K at 15.8 GPa. These results establish a rich temperature-pressure phase diagram for KZnBi and demonstrate a close connection between its superconducting behavior and the electronic structure.