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UID:69d4b37df341d
DTSTART:20250411T080000Z
SEQUENCE:0
TRANSP:OPAQUE
LOCATION:ICFO Auditorium and Online (Teams)
SUMMARY:ICFO | GENG LI
CLASS:PUBLIC
DESCRIPTION:The goal of this thesis is to probe the infrared optical respon
 se of twisted bilayer graphene (TBG) using Fourier transform infrared spec
 troscopy (FTIR). First\, I used a commercial FTIR to measure the TBG in th
 e mid-infrared range at room temperature. I improved the device fabricatio
 n technique and fabricated the TBG devices with a large area and simultane
 ously a low inhomogeneity. I observe that the TBG has abundant optical abs
 orption features originating from the interband transitions that are uniqu
 ely determined by the twist angle.\nThen\, I want to probe the interband t
 ransition of the TBG that lies in the terahertz range\, which evolves the 
 flat band of the TBG that hosts strongly correlated effects. I built a ho
 memade FTIR that works in both the mid-infrared and terahertz range. I wir
 ed the cryostat carefully and achieved an electrical noise level approachi
 ng the Johnson noise limit. By guiding the light from the FITR into the cr
 yostat\, I successfully measured the exciton states in the Bernal bilayer 
 graphene device over a broad spectral range\, demonstrating that the syste
 m is ready for future experimental study of TBG.\n&nbsp\;\nFriday April 11
 \, 10:00 h. ICFO Auditorium and online via Teams\nThesis Director: Prof. D
 r. Frank Koppens
DTSTAMP:20260407T073421Z
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