Pressure-induced superconductivity and topological quantum phase transitions in a quasi-one-dimensional topological insulator: Bi4I4

摘要

Superconductivity and topological quantum states are two frontier fields ofresearch in modern condensed matter physics. The realization ofsuperconductivity in topological materials is highly desired, however,superconductivity in such materials is typically limited to two- orthree-dimensional materials and is far from being thoroughly investigated. Inthis work, we boost the electronic properties of the quasi-one-dimensionaltopological insulator bismuth iodide \b{eta}-Bi4I4 by applying high pressure.Superconductivity is observed in \b{eta}-Bi4I4 for pressures where thetemperature dependence of the resistivity changes from a semiconducting-likebehavior to that of a normal metal. The superconducting transition temperatureTc increases with applied pressure and reaches a maximum value of 6 K at 23GPa, followed by a slow decrease. Our theoretical calculations suggest thepresence of multiple pressure-induced topological quantum phase transitions aswell as a structural-electronic instability.