Evolution of superconductivity in K-doped tris(4-methylphenyl)bismuthine

We report the finding of superconductivity in K-doped tris(4-methylphenyl)bismuthine through both magnetization and resistivity measurements. The evolution of superconductivity and phases with pressure for this new superconductor was examined by the resistivity and Raman scattering measurements. At low pressures below 1.6 GPa, the obtained superconducting transition temperature T_c of 3.6 K remains unchanged. With further increasing pressure, a second superconducting phase with T_c of 7.2 K occurs. The phase transformation is detected by Raman scattering spectra accompanying the T_c enhancement.