Superconductivity in the topological insulator ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ under hydrostatic pressure

We report the resistivity and ac susceptibility measurements of the topological insulator ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ single crystals at pressures up to 11 GPa. Under highly hydrostatic pressure conditions generated in a multi-anvil high-pressure apparatus, a pressure-induced superconductivity only appears above a critical pressure $P_{\mathrm{C}}\sim 7 \mathrm{GPa}$, coinciding with a structural transition from a rhombohedral to a monoclinic structure. The absence of superconductivity in the rhombohedral phase at pressures below $P_{\mathrm{C}}$, which is contrary to previous studies using the high-pressure apparatus with a solid pressure medium, suggests that the occurrence of superconductivity in the rhombohedral phase is sensitive to pressure conditions such as pressure inhomogeneity or uniaxial stress.

Figure 1

Temperature dependence of (a) the resistivity and (b) the Hall coefficient of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ single crystals with applied current in the $ab$ plane.

Figure 2

Temperature dependence of the electrical resistivity of (a) metallic (no. 1) and (b) nonmetallic (no. 2) samples of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ at selected pressures.

Figure 3

Low-temperature part of the electrical resistivity of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ for (a) metallic (no. 1) and (b) nonmetallic (no. 2) samples at selected pressures. (c) Temperature dependence of the ac magnetic susceptibility. The superconducting transition temperature $T_{\mathrm{SC}}$ is defined as the temperature of zero resistance and the onset of the full shielding effect.

Figure 4

(a) Temperature pressure phase diagram of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$. (b) Pressure dependence of the superconducting volume fraction $\left|4\pi \chi \right|$ taken at approximately 2.2 K. The broken line is a guide for the eye.