| Time：1120920 (Wed.) 14:20~15:50 Speaker：Prof.陳則銘(Tse-Ming Chen) 國立成功大學物理學系/Department of Physics, National Cheng Kung University Title：Strain engineering of 2D materials via lithographically engraved hexagonal boron nitride Abstract：Strain engineering is a powerful paradigm for modifying the band structure of 2D materials, and hence enabling their electrical and optical properties to be beautifully engineered. However, it still remains a challenge to arbitrarily control the magnitude and distribution of the strain, limiting the extent to which the strain engineering of 2D materials can effectively operate and advance in both fundamental studies and technological applications. Here, I will present a method that we developed to strain engineer the 2D materials by conforming it onto the hexagonal boron nitride (hBN) with lithographically-patterned surface nanostructures. We then demonstrate the arbitrary control of the strain and hence the phonon scatterings, electronic band structures, and exciton resonances of MoS2 through spatially-resolved Raman spectroscopy and photoluminescence. Moreover, our strain engineering offers a powerful means to significantly and controllably alter the strengths and energies of interlayer excitons. We have also used this approach to realize an unusual electronic state in a corrugated bilayer graphene system in which strain and interlayer interactions are specially engineered to induce pseudo-magnetic fields and break the spatial inversion symmetry. This induces a Rashba-like valley–orbit coupling and creates tilted mini-Dirac cones with non-trivial and anisotropic energy dispersion as well as the momentum-space Berry curvature dipole, thereby giving rise to the nonlinear anomalous Hall effect and a new type of planar Hall effect, namely, the pseudo- planar Hall effect without breaking the time reversal symmetry. The ability to manipulate the non-uniform local strain according to any arbitrary design and to modulate electronic and excitonic properties may create new opportunities in 2D excitonics, optoelectronics, and straintronics. Place：S102, Gongguan Campus, NTNU |
