The triangular relationship between the stacking, band structure and polarization in bilayer h-BN

Sheng-Shong Wong^1*, Zhen-You Lin¹, Sheng-Zhu Ho¹, Chin-En Hsu³, Ping-Hung Li¹, Ching-Yu Chen¹, Yen-Fu Huang¹, Chia-Hao Chen^2,4, Yi-Chun Chen^1,7, Hung-Chung Hsueh³, Cheng-Maw Cheng^2,5,4,6, Chung-Lin Wu^1,2,7

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan
²National Synchrotron Radiation Research Center (NSRRC), Hsinchu, Taiwan
³Department of Physics, Tamkang University, New Taipei City, Taiwan
⁴Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
⁵Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
⁶Taiwan Consortium of Emergent Crystalline Materials, National Science and Technology Council, Taipei, Taiwan
⁷Center for Quantum Frontiers of Research and Technology (QFort), National Cheng Kung University, Tainan, Taiwan

* Presenter:Sheng-Shong Wong, email:L28061525@gs.ncku.edu.tw

The strong correlation in 2D materials has been widely studied since the superconductivity appear in magic-angle twist bilayer graphene system. The degrees of freedom in stacking angle in bilayer 2D system provides an opportunity for creating artificial superlattice structure, in other words, artificial electronic band structure. Nevertheless, the complicated artificial structure (large unit-cell) and many-body effect (Coulomb electrostatic force) are very difficult to solve in nowadays. Here we take hexagonal boron nitride (h-BN) as an example, providing a simple physics picture to explain the link between stacking configuration, electronic band structure and polarization field in homo-structure. The inversion symmetry breaking homo-stacked bilayer h-BN system results in a non-zero polarization field at the interface, further breaking the degeneracy of top and bottom layer h-BN π bands, leading to the π bands splitting at the Brillouin-zone K point. Therefore, in 2D material system, once reaching one of the conditions of the triangular relation – inversion symmetry (breaking) stacked configuration, electronic band crossing (splitting) structure or non-polarization (polarization) field, the other two will show up automatically.

Keywords: hexagonal boron nitride (h-BN), inversion symmetry breaking, band structure, polarization field