FeAs和NiAs超导层的界面调控研究

人工构建异质结构是实现物质新物态的前沿领域。本研究项目将利用分子束外延生长技术制备原子级厚度高质量FeAs和NiAs超导薄膜，构建超导/氧化物异质界面，结合低温强磁场扫描隧道谱与输运测量，研究尺寸效应与界面效应对近二维极限薄膜结构、电荷序和超导性质的影响，探索进一步提高超导转变温度的可能性。进一步利用表面掺杂、替位掺杂以及场效应调节等手段实现载流子浓度调控，表征超导、电荷序、向列性等物性的演化及相互关联。研究各类超导薄膜中磁性原子和非磁性原子杂质态和磁通中心的准粒子态，探索杂质对超导的影响，揭示超导电子配对的对称性和配对机制。结合FeSe/SrTiO3体系结果，揭示界面增强超导的关键因素，深入理解界面增强超导的机制。这一项目的顺利开展将对理解高温超导机理以及发现更高转变温度的超导材料都具有重要意义。

Engineering of heterostructures is a vibrant frontier in realizing novel electronic states of matter. In this project, we plan to prepare ultrathin FeAs and NiAs superconducting films on SrTiO3 substrates by molecular beam epitaxial growth and perform in-situ scanning tunneling spectroscopy and transport measurement to characterize the lattice and electronic properties tuned by size effect and interface effect, as well as to increase the superconducting transition temperature. We will also modulate the doping level by surface doping, substitution and electric field effect, and then check the evolution of superconductivity, charge density waves and nematicity to disclose their correlation or competition. Furthermore, we will study the impurity states induced by magnetic and non-magnetic atoms and bound states at the center of a vortex to check the pairing symmetry. Based on the above experimental study and the comparison with FeSe/SrTiO3, we expect to figure out the key factors for enhancing superconductivity and understand the mechanism of interface superconductivity. This project may shed new light on our understanding on high temperature superconductivity and searching for new high temperature superconductors.