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Public Seminar of PhD Candidate:
Quantum transport studies on graphene-transition metal dichalcogenides heterostructures

Speaker:Ms. Qing RAO
Affiliation:The University of Hong Kong
Date:September 18, 2023 (Monday)
Time:2:00 p.m.
Venue:[In Person] Room 522, 5/F, Chong Yuet Ming Physics Building, The University of Hong Kong
Meeting ID: 966 9677 9421
Password: 666080


Van der Waals interactions with transition metal dichalcogenides (TMDCs) were shown to induce strong spin-orbit coupling (SOC) in graphene, offering great promises to combine large experimental flexibility of graphene with unique tuning capabilities of SOC. In this talk, I will present our study on the monolayer and bilayer graphene-WSe2 system, where we have successfully demonstrated ballistic carrier transport and provided spectroscopic evidence of the spin-orbit-coupled bands by measuring the ballistic transverse magnetic focusing (TMF). Possible suppression of electron-electron scatterings was also found in temperature dependence measurement. Further, the difference in TMF and SdH oscillation measurements indicates a fundamental origin behind it, calling for in-depth studies. In addition, I will also show the microneedle manipulation technique we developed based on the van der Waals transfer system, where one can scratch the flakes into a designated shape with a precision at micrometer scales, move, rotate, roll-up, and exfoliate the flakes to help building various types of heterostructures, and form electric contacts by directly drawing/placing thin metal wires over the flake. It therefore can help us to fabricate simple devices or build van der Waals heterostructures from different 2D materials irrespective of their sensitivities to the environments. Our work on graphene-TMDC van der Waals heterostructures demonstrates an interesting possibility to exploit ballistic electron motion pronounced in graphene, to control or detect spin by varying the ballistic electron motion, and therefore offers a potential platform for ballistic spin-orbitronics.

Anyone interested is welcome to attend.