Pressure induced superconductivity in Bi_2Se_(1.2)Te_(1.8) topological insulator

摘要

The evolution of electrical transport under external pressure has been investigated by performing low temperature (4-300K) high pressure (0 - 8 GPa) resistance measurements on single crystals of Bi_2Se_(1.2)Te_(1.8) topological insulator. The application of pressure is seen to profoundly affect the ground state properties of this system by causing two interesting electronic phase transitions. Initially an insulator to metal transition steps in at a moderate pressure of about 2 GPa below the temperature of 150K, which permeates throughout the entire temperature range with gradual increase in pressure. Subsequent increase in pressure leads to a metal to superconductor transition at around 3.5 GPa pressure. Superconducting transition temperature (T_c) is found to decrease monotonically with increasing pressure from a value of 6.8K at 3.5 GPa to 6.4 K at 7 GPa, a trend usually seen in many conventional superconductors.