Moiré Superlattice-Induced Superconductivity in One-Unit-Cell FeTe.

In this work, we demonstrate that the nonsuperconducting single-layer FeTe can become superconducting when its structure is properly tuned by epitaxially growing it on Bi2Te3 thin films. The properties of the single-layer FeTe deviate strongly from its bulk counterpart, as evidenced by the emergence of a large superconductivity gap (3.3 meV) and an apparent 8 × 2 superlattice (SL). Our first-principles calculations indicate that the 8 × 2 SL and the emergence of the novel superconducting phase are essentially the result of the structural change in FeTe due to the presence of the underlying Bi2Te3 layer. The structural change in FeTe likely suppresses the antiferromagnetic order in the FeTe and leads to superconductivity. Our work clearly demonstrates that moiré pattern engineering in a heterostructure is a reachable dimension for investigating novel materials and material properties.