Recent progresses in the growth and fabrication techniques for preparing crystalline two-dimensional (2D) superconductors have stimulated intense interest in the studies of the electronic properties of these systems. Here we investigate the superconducting transport properties based on chemical vapor deposition-grown thin NbC crystals consisting of network structures. The 2D character of the superconductivity in individual NbC crystals is revealed by examining the angular dependence of magnetotransport measurements. At low temperatures, the samples show nonmonotonic double-step superconducting transitions as a function of temperature and magnetic field. We demonstrate that the observed transport characteristics can be understood in terms of coupled Josephson junctions forming between isolated NbC crystals, including the effects of Josephson and quasiparticle tunneling. In particular, detailed analysis of the magnetic field-driven transition suggests the existence of quantum flux-creep regime at low temperatures and small magnetic fields in such thin NbC superconducting crystals. Our work underlines the importance of the morphology on the transport properties of 2D superconducting crystals, providing a comprehensive understanding of crystalline 2D superconductors.

中文翻译：

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通过弱连接连接的二维NbC超导晶体网络传输

用于制备晶体二维（2D）超导体的生长和制造技术的最新进展引起了对这些系统的电子性质的研究的强烈兴趣。在这里，我们研究基于化学气相沉积生长的由网络结构组成的薄NbC晶体的超导传输特性。通过检查磁传输测量的角度依赖性，可以揭示单个NbC晶体中超导性的2D特性。在低温下，样品显示出非单调双步超导转变与温度和磁场的关系。我们证明观察到的传输特性可以理解为在孤立的NbC晶体之间形成耦合的约瑟夫森结，包括约瑟夫森效应和准粒子隧穿效应。特别地，对磁场驱动的跃迁的详细分析表明，在这种薄NbC超导晶体中，在低温和小磁场下存在量子通量-蠕变态。我们的工作强调了形态对二维超导晶体传输特性的重要性，从而提供了对晶体二维超导体的全面理解。