Large surface conductance and two-dimensional superconductivity in microstructured crystalline topological insulators

TL;DR

This study demonstrates that microfabrication of indium-doped topological insulators significantly enhances surface conductance and induces two-dimensional superconductivity, opening new avenues for quantum device applications.

Contribution

It introduces a microfabrication approach that boosts surface conductance and reveals 2D superconductivity in topological insulators, advancing their practical utility.

Findings

Surface conductance contribution reaches 30% near room temperature.

Surface contribution becomes dominant below approximately 180 K.

Emergence of two-dimensional superconductivity below 6 K.

Abstract

Controllable geometric manipulation via micromachining techniques provides a promising tool for enhancing useful topological electrical responses relevant to future applications such as quantum information science. Here we present microdevices fabricated with focused ion beam from indium-doped topological insulator Pb1-xSnxTe. With device thickness on the order of 1 {\mu}m and an extremely large bulk resistivity, we achieve an unprecedented enhancement of the surface contribution to about 30% of the total conductance near room temperature. The surface contribution increases as the temperature is reduced, becoming dominant below approximately 180 K, compared to 30 K in mm-thickness crystals. In addition to the enhanced surface contribution to normal-state transport, we observe the emergence of a two-dimensional superconductivity below 6 K. Measurements of magnetoresistivity at high magnetic fields reveal a weak antilocalization behavior in the normal-state magnetoconductance at low temperature and a variation in the power-law dependence of resistivity on temperature with field. These results demonstrate that interesting electrical response relevant to practical applications can be achieved by suitable engineering of single crystals.