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关于11月26日(周一)马天星学术报告的通知

编辑:phyzt 时间:2018年11月22日 访问次数:133

题目:Magnetic and superconducting correlation in monolayer and twisted bilayer graphene

报告人:马天星 北京师范大学

地点: 教十二-201

时间: 1126日,周一,10:00-11:00

 

Abstract

Using exact quantum Monte Carlo method, we identify the phase diagram of the half filled, the lightly doped and heavily doped graphene, which shows 
a rather rich physical properties. At half filling, the system is driven to a Mott insulator with antiferromagnetic long range order by increasing interaction, 
and a transition from a d+id pairing to a p+ip pairing is revealed, depends on the next-nearest hoping and the electronic fillings. We also examine the 
recent novel electronic states seen in magic-angle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation 
angle θ=1.08, we reveal that an antiferromagnetically ordered Mott insulator emerges beyond a critical U c at half filling, and with a small doping, the 
pairing with d+id symmetry dominates over other pairings at low temperature. The effective d+id pairing interaction strongly increase as the on-site 
Coulomb interaction increases, indicating that the superconductivity is driven by electron-electron correlation. Our non-biased numerical results
 demonstrate that the twisted bilayer graphene share the similar superconducting mechanism of high temperature superconductors, which is a new 
and idea platform for further investigating the strongly correlated phenomena.
 

报告人简介

马天星,北京师范大学物理学系教授,博士研究生导师。分别于2000年7月和2005年7月在北京师范大学获得学士和博士学位。2005年8月至2010年6月先后在复旦大学、德国马普所、香港中文大学从事凝聚态物理理论方面的博士后研究。2010年7月至今在北京师范大学物理学系工作。主要从事电子关联体系磁性和超导电性的研究,包括石墨烯、铁基超导体、有阻挫系统等,已在Phys. Rev. Lett.、Phys. Rev.B,Appl. Phys. Lett.等上发表50余篇学术论文。主持或完成多项国家自然科学基金项目、1项北京市优秀人才项目,参与1项国家自然科学基金重点项目。


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