Two-Dimensional Superconductivity at the LaAlO 3 / KTaO 3 ( 110 ) Heterointerface

Zheng Chen, Zhongran Liu, Yanqiu Sun, Xiaoxin Chen, Yuan Liu, Hui Zhang, Hekang Li, Meng Zhang, Siyuan Hong, Tianshuang Ren, Chao Zhang, He Tian, Yi Zhou, Jirong Sun, and Yanwu Xie

We report on the observation of a $T_c\sim 0.9K$ superconductivity at the interface between ${\mathrm{LaAlO}}_3$ film and the $5d$ transition metal oxide ${\mathrm{KTaO}}_3\left(110\right)$ single crystal. The interface shows a large anisotropy of the upper critical field, and its superconducting transition is consistent with a Berezinskii-Kosterlitz-Thouless transition. Both facts suggest that the superconductivity is two-dimensional (2D) in nature. The carrier density measured at 5 K is $\sim 7\times {10}^{13}{\mathrm{cm}}^{-2}$. The superconducting layer thickness and coherence length are estimated to be $\sim 8$ and $\sim 30\mathrm{nm}$, respectively. Our result provides a new platform for the study of 2D superconductivity at oxide interfaces.

Phys. Rev. Lett. 126, 026802 

The published article is available at https://link.aps.org/doi/10.1103/PhysRevLett.126.026802