Quantum Griffiths Singularity in 2D Superconductors and Logarithm Law Quantum Oscillations in Ultra-quantum Semimetals

Speaker: 王健 (北京大学)

Time: April 28, 2017 14:30

Place: 理科楼三楼报告厅

Abstract: Quantum phase transition is one of most important topics in condensed matter physics. When we study the superconductor-metal transition in ultrathin crystalline Ga films grown on GaN substrate, we firstly discover quantum Griffiths singularity in two dimensional (2D) system and superconductors, which is a new quantum phase transition in 2D superconductors. This discovery is further revealed in LAO/STO (110) interface superconductors and monolayer NbSe2 films. In addition, a new class of quantum oscillations in topological semimetals beyond quantum limit has been discovered recently, where the resistivity periodically oscillates with logB. The discovery of the clear logarithm law quantum oscillations not only provides new insight into the nature of three-dimensional electronic states beyond the quantum limit but also indicates the first realization of fermionic Efimov bound states (arXiv:1704.00995).

Bio: Jian Wang, received his BS 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 elected to Fellow of China Thousand Talents Program for Young Scientist in 2011, Chief Scientist for National Young Scientists Projects in 2012, and Changjiang Distinguished Professor of China's Ministry of Education in 2016. He won China National Fund for Excellent Young Scientists in 2012 and Sir Martin Wood China Prize in 2015. Currently, he is the Guest Editor of 2D Materials, the Editor Board Member of Scientific Reports, and AIP China Advisory Board Member etc. His current research interests are quantum transport properties of topological materials and low dimensional superconductors.