Topic：New Progress in 2D crystalline superconductors

　　Speaker:  Jian Wang (王健)
　　　　　　　International Center for Quantum Materials，School of Physics, Peking University

　　Time: 15:30-17:30, (Wednesday) September 19^th, 2018

　　Venue: Room 403，Shi Changxu Building, IMR CAS

　　By direct transport and magnetic measurements, we provide fist direct evidence for high temperature superconductivity in the 1-UC FeSe films grown on insulating STO substrates with the onset Tc and critical current density much higher than those for bulk FeSe.[1] The investigation may pave the way to enhancing and tailoring superconductivity by interface engineering. Besides, quantum phase transition is one of most important topics in condensed matter physics. When we study the superconductor-metal transion in ultrathin crystalline Ga films grown on GaN substrate [2], for the first time quantum Griffiths singularity in two dimensional (2D) systems [3] is discovered as a new quantum phase transition in 2D superconductors. The coexistence of quantum Griffiths singularity and Ising (Zeeman-protected) superconductivity is further revealed in monolayer NbSe2 films[4]. We also demonstrate that by interface engineering Zeeman-protected superconductivity can be artificially induced in crystalline 2D superconducting heterostructures [5].

　　References

　　[1] Chin. Phys. Lett. 31, 017401 (2014) (with a higlight: Science 343, 230 (2014))

　　[2] Physical Review Letters 114, 107003 (2015) (Editors’ Suggestion)

　　[3] Science 350, 542 (2015) (with a perspective article: Science 350, 509(2015))

　　[4] Nano Letters 17, 6802 (2017)

　　[5] Phys. Rev. X 8, 021002 (2018)

　　Brief biography

　　Jian Wang, Changjiang Distinguished Professor of China's Ministry of Education, received his bachelor’s degree in Physics from Shandong University in 2001, and PhD degree in condensed matter physics from Institute of Physics, Chinese Academy of Sciences in 2007. From 2006 to 2011, he worked as a Postdoc and Research Associate at Penn State University, USA. He became an Associate Professor at Peking University in 2010 and Professor in 2017. He was selected to Chief Scientist for National Young Scientists Projects in 2012, Changjiang Distinguished Professor of China's Ministry of Education in 2016 and Leader for National Key R&D Program of China in 2018. He won China National Fund for Excellent Young Scientists in 2012 and Sir Martin Wood China Prize in 2015. His current research interests are qauntum transport properties of low dimensional superconductors and topological materials. The team led by Jian Wang discovered quantum Griffiths singularity in 2D superconductors, demonstrated high Tc in one unit cell thick FeSe films, observed interface-modulated Ising superconductivity, detected tip-induced unconventional superconductivity in topological materials, revealed eletron-electron interaction in topological materials, and studied the interaction between topological or ferromagnetic materials and superconductors. In recent years, he has authored more than 60 papers including Science, Nature Materials, Nature Physics, Nature Nanotechnology etc. He has obtained 8 patents and presented tens of invited talks at international meetings/conferences, such as American Physical Society March Meeting (2011, 2016). Currently, he is the Guest Editor of 2D Materials, and AIP China Advisory Board Member etc. Jian Wang's lab at Peking University possesses low temperature scanning tunneling microcopy/spectroscopy-molecular beam epitaxy combined ultrahigh vacuum system, ultralow temperature-high magnetic field measurement system etc.

　　王健，北京大学教授、教育部长江学者特聘教授。2007年于中国科学院物理研究所获博士学位，2006-2011年先后在美国宾夕法尼亚州立大学做博士后与Research Associate。2010-2017年在北京大学任研究员、博导，2017年晋升为教授。2012年入选首批基金委优秀青年基金、首批科技部青年科学家专题项目负责人，2015年荣获马丁伍德爵士中国物理科学奖、入选首届中国十大新锐科技人物，2016年入选教育部长江学者特聘教授。王健带领的课题组和科研团队首次在二维超导体系中发现量子格里菲思奇异性，通过电输运手段证实了单层FeSe中的高温超导特性，创新性地通过界面调控实现了伊辛超导，将针尖硬点接触技术发展成一种探索拓扑超导的新方法，首次发现拓扑材料中的电子-电子相互作用，以及在拓扑材料或磁性材料与超导体的异质结构方向做出一系列重要成果。当前王健的主要研究兴趣为低维超导与拓扑材料的物性，近年来在相关领域发表SCI论文60多篇，其中以通讯作者发表Science 1篇（被同期Science高亮报道）、Nature Materials 1篇、Nature Physics 1篇(被同期Nature Physics高亮报道)、PNAS 1篇、Physical Review X 2篇、Phyiscal Review Letter 2篇、 Nano Letters 4篇（含一作）等。此外通讯作者发表在Chinese Physics Letters上的论文被Science的编辑特选报道。