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  • 理学院数理讲坛(2018年第47讲)
  • 发布时间:2018年11月28日 15:48 作者: 点击:[]
  • 理学院数理讲坛2018年第47讲) 

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

    报 告 人: 马天星教授

    位: 北京师范大学

    报告时间:2018124日(星期二10:00-11:00

    报告地点:龙赛理科楼116

    报告摘要: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 Uc 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20007月和20057月在北京师范大学获得学士和博士学位。

    20058月至20106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。

    20107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. BAppl. 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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