Chin. Phys. Lett.  2018, Vol.35 Issue (2): 027303  DOI:10.1088/0256-307X/35/2/027303
Observation of Tunneling Gap in Epitaxial Ultrathin Films of Pyrite-Type Copper Disulfide
1State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 1000842Collaborative Innovation Center of Quantum Matter, Beijing 100084>

### Abstract

We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide. Layer-by-layer growth of CuS$_{2}$ films with a preferential orientation of (111) on SrTiO$_{3}$(001) and Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ substrates is achieved by molecular beam epitaxy growth. For ultrathin films on both kinds of substrates, we observe symmetric tunneling gap around the Fermi level that persists up to $\sim$15 K. The tunneling gap degrades with either increasing temperature or increasing thickness, suggesting new matter states at the extreme two-dimensional limit.

### 基金资助

Supported by the National Natural Science Foundation of China under Grant Nos 11574174, 11774193 and 11790311, and the National Basic Research Program of China under Grant No 2015CB921000.

### 引用本文

[英文]
Chong Liu, Haohao Yang, Can-Li Song, Wei Li, Ke He, Xu-Cun Ma, Lili Wang, Qi-Kun Xue. Observation of Tunneling Gap in Epitaxial Ultrathin Films of Pyrite-Type Copper Disulfide[J]. CPL, 2018, 35(2): 027303.

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