Tailoring of interlayer coupling and exciton-exciton interaction in van der Waals bilayers

Wei-Ting Hsu^1,2*, Cheng-Syuan Cai^1,3, Chi-Ruei Pan⁴, Peng-Jen Chen⁴, Ro-Ya Liu³, Xiaoqin Li², Wen-Hao Chang^5,6, Jung-Fu Lin⁷, Mei-Yin Chou⁴, Chih-Kang Shih²

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, The University of Texas at Austin, Austin, Texas, USA
³National Synchrotron Radiation Research Center, Hsinchu, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
⁵Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
⁶Center for Emergent Functional Matter Science (CEFMS), National Yang Ming Chiao Tung University, Hsinchu, Taiwan
⁷Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA

* Presenter:Wei-Ting Hsu, email:wthsu@phys.nthu.edu.tw

Strong Coulomb interactions in two-dimensional materials, such as interlayer hybridization and exciton-exciton interaction, play a key role in determining electronic and optical properties. In this context, exploring external tuning knobs for manipulating them has emerged as a potential route to realize controllable electronic systems based on van der Waals (vdW) bilayers. In this work, we have investigated the tuning of Coulomb interactions by applying gigapascal hydrostatic pressure or by hetero-stacking on vdW bilayers. Our results demonstrate several-fold (orders of magnitude) tuning of the coupling strength (annihilation rate), which provides a promising strategy for designing novel two-dimensional electronic systems.

Keywords: van der Waals bilayer, transition metal dichalcogenide, interlayer coupling, exciton-exciton interaction