Reversibility of Superconductivity in CuxBi2Se3 via Quenching Conditions*

We investigated the effect of various growth and annealing conditions on Cu$_{0.3}$Bi$_{2}$Se$_{3}$, a compound proposed to host topological superconductivity. For annealing temperature $T > 580^{\circ}$C, quenching was found necessary for superconductivity, and the superconductivity loss due to not quenching after annealing was reversible by further annealing and quenching. For $T < 580^{\circ}$C, annealing was detrimental, even when followed by quenching. Floating zone growth and the annealing of thin ($< 1$ mm) crystals were found to be detrimental to superconductivity.