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.
@article{arxiv.1908.10427,
title = {Large surface conductance and two-dimensional superconductivity in microstructured crystalline topological insulators},
author = {Yangmu Li and Jie Wu and Fernando Camino and G. D. Gu and Ivan Božović and John M. Tranquada},
journal= {arXiv preprint arXiv:1908.10427},
year = {2019}
}