Institute of Physics,école Polytechnique Fédérale de Lausanne (EPFL),CH-1015 Lausanne,Switzerland

Abstract：

For more than a century, the notion of band structure remained the most important instrument for studying crystalline solids in the physics community. At the same time, an even older picture of chemical bonding, usually considered at an empirical level, continues serving the chemistry community. The Wannier function formalism provides a rigorous connection between these two complementary points of view. In my seminar, I would like to show a number of examples of applying this formalism to understanding and accurate modelling of two-dimensional materials and moiré heterostructures. I will first explain how the intrinsic gauge freedom of Wannier functions can be exploited for explaining the structural and chemical trends [1] across the entire family of transition metal dichalcogenides [2] as well as the tendency towards forming charge-density-wave and distorted phases in these materials [3]. The second part of my seminar is dedicated to constructing tight-binding Hamiltonians for accurate modelling of moiré heterostructures. I will take twisted double bilayer graphene as a starting point [4-6] and present our recent results on related graphene systems modelled using large-scale tight-binding model calculations [7-11].

References：

[1] D. Pasquier and O. V. Yazyev,“Crystal field,ligand field,and interorbital effects in two-dimensional transition metal dichalcogenides across the periodic table”,2D Mater. 6,025015 (2019).

[2] S. Manzeli,D. Ovchinnikov,D. Pasquier,O. V. Yazyev and A. Kis,“2D transition metal dichalcogenides”,Nat. Rev. Mater. 2,17033 (2017).

[3] D. Pasquier and O. V. Yazyev,“Unified picture of lattice instabilities in metallic transition metal dichalcogenides”,Phys. Rev. B 100,201103 (2019).

[4] C. Shen,Y. Chu,Q. Wu,N. Li,S. Wang,Y. Zhao,J. Tang,J. Liu,J. Tian,K. Watanabe,T. Taniguchi,R. Yang,Z. Y. Meng,D. Shi,O. V. Yazyev and G. Zhang,“Correlated states in twisted double bilayer graphene”,Nat. Phys. 16,520 (2020).

[5] F. Haddadi,Q. Wu,A. J. Kruchkov and O. V. Yazyev,“Moiré Flat Bands in Twisted Double Bilayer Graphene”,Nano Lett. 20,2410 (2020).

[6] Q. Wu,J. Liu,Y. Guan and O. V. Yazyev,“Landau Levels as a Probe for Band Topology in Graphene Moiré Superlattices”,Phys. Rev. Lett. 126,056401 (2021).

[7] N. V. Tepliakov,Q. Wu and O. V. Yazyev,“Crystal Field Effect and Electric Field Screening in Multilayer Graphene with and without Twist”,Nano Lett. 21,4636 (2021).

[8] S. Zhang,B. Xie,Q. Wu,J. Liu and O. V. Yazyev,“Chiral Decomposition of Twisted Graphene Multilayers with Arbitrary Stacking”,Nano Lett. 23,2921 (2023).

[9] M. Brzezińska and O. V. Yazyev,“Flat bands in bilayer graphene induced by proximity with polar h-BN superlattices”,arXiv:2305.09749.

[10] M. Brzezińska,Y. Guan,O. V. Yazyev,S. Sachdev and A. Kruchkov,“Engineering SYK Interactions in Disordered Graphene Flakes under Realistic Experimental Conditions”,Phys. Rev. Lett. 131,036503 (2023).

[11] Y. Guan,C. Dutreix,H. Gonzales-Herrero,M. M. Ugeda,I. Brihuega,M. I. Katsnelson,O. V. Yazyev and V. T. Renard,“Observation of Kekulé vortices induced in graphene by hydrogen adatoms”,Nat. Commun. 15,2927 (2024).

About the speaker:

Prof. Oleg Yazyev obtained his degree in chemistry from Moscow State University in 2003 and then joined Ecole Polytechnique Fédérale de Lausanne (EPFL) completing his Ph.D. thesis in 2007. He spent the next two years as a postdoctoral fellow at the Institute of Theoretical Physics (ITP) and the Institute for Numerical Research in the Physics of Materials (IRRMA) of the same institution. In 2009-2011 he was a postdoctoral fellow at the Department of Physics of the University of California, Berkeley, and the Lawrence Berkeley National Laboratory. In September 2011 he started an independent research group supported by the Swiss National Science Foundation professorship grant. In 2012 he was awarded an ERC Starting grant. His current research focuses on the theoretical and computational physics of two-dimensional and topological materials with a strong emphasis on their prospective technological applications.

邀请人：吴泉生   特聘研究员

联系人：何  露   helu@iphy.ac.cn

报告地点：物理所中关村园区M楼253会议室