Magnetotransport Properties in High-Quality Ultrathin Two-Dimensional Superconducting Mo2C Crystals

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• 作者：Libin Wang ; Chuan Xu ; Zhibo Liu ; Long Chen ; Xiuliang Ma ; Hui-Ming Cheng ; Wencai Ren ; Ning Kang
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：10
• 期：4
• 页码：4504-4510
• 全文大小：432K
• 年卷期：0
• ISSN：1936-086X

文摘

Ultrathin transition metal carbides are a class of developing two-dimensional (2D) materials with superconductivity and show great potentials for electrical energy storage and other applications. Here, we report low-temperature magnetotransport measurements on high-quality ultrathin 2D superconducting α-Mo₂C crystals synthesized by a chemical vapor deposition method. The magnetoresistance curves exhibit reproducible oscillations at low magnetic fields for temperature far below the superconducting transition temperature of the crystals. We interpret the oscillatory magnetoresistance as a consequence of screening currents circling around the boundary of triangle-shaped terraces found on the surface of ultrathin Mo₂C crystals. As the sample thickness decreases, the Mo₂C crystals exhibit negative magnetoresistance deep in the superconducting transition regime, which reveals strong phase fluctuations of the superconducting order parameters associated with the superconductor–insulator transition. Our results demonstrate that the ultrathin superconducting Mo₂C crystals provide an interesting system for studying rich transport phenomena in a 2D crystalline superconductor with enhanced quantum fluctuations.