Pressure-induced double-dome superconductivity in kagome metal CsTi3Bi5

We present high-pressure resistance measurements up to 40 GPa on recently discovered titanium-based kagome metal CsTi${}_3$Bi${}_5$. At ambient pressure, CsTi${}_3$Bi${}_5$ shows no evidence of superconductivity in resistivity and specific heat. By applying pressure, superconductivity emerges and the superconducting transition temperature $T_{\mathrm{c}}$ reaches its first maximum of 1.2 K at $\sim$5 GPa. Then the $T_{\mathrm{c}}$ is suppressed by pressure and cannot be detected around 10 GPa, manifesting as a superconducting dome. Remarkably, upon further increasing pressure above $\sim$13 GPa, another superconducting dome shows up, with the maximum $T_{\mathrm{c}}$ of 0.6 K and ending pressure at $\sim$36 GPa. The variation of $T_{\mathrm{c}}$ displays a clear double-dome shape in the superconducting phase diagram. Our work demonstrates the similarity between CsTi${}_3$Bi${}_5$ and CsV${}_3$Sb${}_5$, providing valuable insights into the rich physics of these novel kagome metals.