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arXiv · 1907.03521

Phase evolution and superconductivity enhancement in Se-substituted MoTe$_2$ thin films

Peiling Li·Jian Cui·Jiadong Zhou·Dong Guo·Zhenzheng Zhao·Jian Yi·Jie Fan·Zhongqing Ji·Xiunian Jing·Fanming Qu·Changli Yang·Li Lu·Junhao Lin·Zheng Liu·Guangtong Liu
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Abstract

The strong spin$-$orbit coupling (SOC) and numerous crystal phases in few$-$layer transition metal dichalcogenides (TMDCs) MX$_2$ (M$=$W, Mo, and X$=$Te, Se, S) has led to a variety of novel physics, such as Ising superconductivity and quantum spin Hall effect realized in monolayer 2H$-$ and Td$-$MX$_2$, respectively. Consecutive tailoring of the MX$_2$ structure from 2H to Td phase may realize the long$-$sought topological superconductivity in one material system by incorporating superconductivity and quantum spin Hall effect together. In this work, by combing Raman spectrum, X-ray photoelectron spectrum (XPS), scanning transmission electron microscopy imaging (STEM) as well as electrical transport measurements, we demonstrate that a consecutively structural phase transitions from Td to 1T$'$ to 2H polytype can be realized as the Se-substitution concentration increases. More importantly, the Se$-$substitution has been found to notably enhance the superconductivity of the MoTe$_2$ thin film, which is interpreted as the introduction of the two$-$band superconductivity. The chemical constituent induced phase transition offers a new strategy to study the s$_{+-}$ superconductivity and the possible topological superconductivity as well as to develop phase$-$sensitive devices based on MX$_2$ materials.

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Peiling Li, Jian Cui, Jiadong Zhou, Dong Guo, Zhenzheng Zhao, Jian Yi, Jie Fan, Zhongqing Ji, Xiunian Jing, Fanming Qu, Changli Yang, Li Lu, Junhao Lin, Zheng Liu, Guangtong Liu. 2019-07-08. Phase evolution and superconductivity enhancement in Se-substituted MoTe$_2$ thin films. https://doi.org/10.1002/adma.201904641

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