Title

Layer pseudospin magnetism and electric field induced anomalous Hall effects in rhombohedral multilayer graphene

Speaker

Prof. Jeil Jung

University of Seoul, Korea

Time

10：00am, October 30, 2024

Place

Material Science and Research Building B902

2005, PhD Universidad Nacional de Educacion a Distancia (UNED), supervisor Jose Enrique Alvarellos, Madrid, Spain.

2025-2026, National Center for Theoretical Sciences, Hsinchu, Taiwan

2006-2013 University of Texas at Austin, supervisor Allan MacDonald. Fulbright research fellow, lecturer.

2013-2015 National University of Singapore, supervisor Shaffique Adam, Senior Research Fellow.

2015-present  City University of Seoul. Professor.

Research interests:

Electronic structure of twisted bilayer and multilayer graphene, condensed matter theory, development of exchange-correlation functionals in density functional theory, Electron-electron interactions in graphene, moire patterns.

Abstract

Recent experiments have revealed the possibility of achieving sizeable Coulomb interaction driven gapped phases in dual gated rhombohedral multilayer graphene devices where carrier densities and perpendicular electric fields can be simultaneously controlled. Of particular importance are the pentalayer and tetralayer devices whose spontaneous gaps of the order of ten meV are attributable to layer pseudospin polarization of the states near the Dirac point in chiral 2DEG systems. In this talk I will revisit the notion of pseudospin magnetism in bilayer graphene discussed long ago that keeps close relationship with recent observations of spontaneously gapped phases in rhombohedral multilayer graphene. The layer pseudospin polarization can take place in a variety of ways leading to different Hall conductivities depending on the signs of the mass terms for each one of the spin-valley flavors. By means of mean-field Hartree-Fock approach we examine and compare the self-consistent solutions corresponding to the different pseudospin magnetic phases. We comment on the energetics involved in the spontaneous spin-valley polarization when we add a finite carrier doping in the presence of perpendicular electric fields. We finally discuss on the role of moire patterns due to an aligned hexagonal boron nitride substrate brought in contact with graphene layers.