Atomically thin high-temperature superconductors

The emergent technique of van der Waals stacking has started to impact on high temperature superconductivity [1][2]. Here we report the realization of superconducting unprotected Bi₂Sr₂CaCu₂O_8+δ (BSCCO) flakes down to 2.5 unit cells for studying high T_c superconductivity mechanism. We employ a novel solid state gating technique to effectively tune the carrier density of thin flakes, inducing the superconductor-insulator transition (SIT) in BSCCO. The corresponding evolution of the density of states (DOS) is unveiled by using planar tunnel junctions of graphite/BSCCO. The combination of gate tuning and tunneling spectroscopy shall be applicable to other two-dimensional materials.

[1] M. Liao, Y. Zhu, J. Zhang, R. Zhong, J. Schneeloch, G. D. Gu, K. Jiang, D. Zhang, X. Ma, and Q. K. Xue, Nano Lett. 18, 5660 (2018).
[2] S. Y. F. Zhao, N. Poccia, M. G. Panetta, C. Yu, J. W. Johnson, H. Yoo, R. Zhong, G. D. Gu, K. Watanabe, T. Taniguchi, S. V. Postolova, V. M. Vinokur, and P. Kim, arXiv: 1809.06944.