New superconducting phase of Bi2Te3 under pressure above 11 GPa

We have investigated the pressure dependence of superconducting transition temperature Tc of Bi2Te3 through electrical resistance measurement under high pressure up to 13 GPa. The value of zero-resistance critical-temperature Tczero is 2.7 K at 9.0 GPa. Pressurization up to 11 GPa reduces the Tczero. However the pressurization at 13 GPa causes sudden enhancement of Tczero, which is obtained to be 3.7 K. The onset temperature of superconducting transition Tconset shows the positive pressure dependence under pressure above 10 GPa. The value of Tconset is obtained to be 5.0 K at 13 GPa. The sharp increase of Tczero and the positive pressure dependence of Tconset suggest a presence of new superconducting phase.