When Ferrovalley met Twisty

报告题目:When Ferrovalley met Twisty

报告人:段纯刚教授 华东师范大学



报告摘要: Ferrovalley materials are systems with spontaneous valley polarization. In this work, we show a left or right twist near 30° twisted ferrovalley bilayers will change the Berry curvature of the system, which can be regarded as introducing an emergent chiral U(1) gauge field. Interestingly, this induced gauge field forms chirality dependent skyrmion pattern. Moreover, such Berry curvature change also induce the electronic polarization of the bilayer system. Therefore, the antiferromagnetically coupled twisted bilayer system is indeed also antiferroelectric due to the spin-layer locking effect. Hence, when we apply external electric field to break the potential balance between layers, there will emerge novel magnetoelectric coupling and exotic chirality dependent dielectricity. For example, the left twisted system could even demonstrate negative susceptibility, i.e. the induced polarization is opposite to the applied field, which is very rare in the nature. These findings not only enrich our understanding on Moiré systems and ferrovalley materials, but also open an appealing route toward functional 2D materials design for electronic, optical and even energy storage devices.

报告人简介:段纯刚,华东师范大学紫江特聘教授,教育部创新团队带头人,国家杰出青年基金获得者,国家“万人计划”领军人才。1994年武汉大学物理系本科毕业,1998年中科院物理所理论物理博士毕业。1998年至2007年在美国从事研究工作,2008年加入华东师范大学,目前担任极化材料与器件教育部重点实验室主任,华东师范大学物理与电子科学学院常务副院长。主要从事固体材料结构和物性研究,近期研究领域包括自旋电子材料、谷电子材料和多铁体,铁电、铁磁和多铁隧道结,以及基于铁电和多铁体的类脑研究,在Nature Elec., Nature Commun., Nano Lett.PRL, Adv. Mater.等国际著名学术刊物上共发表学术论文210余篇,SCI引用逾6000次,其中16篇引用过百。曾获第十二届上海市自然科学牡丹奖(2017),现为中国材料研究学会计算材料学分会委员, 中国硅酸盐学会微纳技术分会委员、上海计算物理专业委员,现任J. Physics. Conden. Matt.Frontier in Physics(瑞士)J. Materiomics编委。