School of Science Department of Physics 63 Fabrication of Moiré Superlattices from Exfoliated 2D Materials Supervisor: Berthold JAECK / PHYS Student: CHAN Sze Chit / PHYS Course: UROP 1000, Summer Two-dimensional moiré superlattices are currently one of the most popular research topics in condensed matter physics due to their unique properties, such as superconductivity and other quantum effects, including the fractional quantum anomalous Hall effect and quantum metric, which are rarely observed in other materials. Consequently, fabrication of 2D moiré superlattices has been a critical role for further investigation and research of different quantum phenomena. The mechanical exfoliation method was adopted in this study. Specifically, the efficiency of Scotch-tape exfoliation for producing monolayers and bilayers graphene is investigated, with optimization parameters such as peeling speed and methodology to improve yield of large-area, thin flakes. Fundamental insights into the scalable production of high-quality moiré superlattices for quantum research are provided through this work. Fabrication of Moiré Superlattices from Exfoliated 2D Materials Supervisor: Berthold JAECK / PHYS Student: CHENG Tsz Hin / PHYS Course: UROP 1100, Spring UROP 2100, Summer Magic-Angle Twisted Bilayer Graphene (MATBG) has received much attention in both the Quantum Physics and Nanotechnology fields due to its unique characteristics in recent years. MATBG is formed by stacking two layers of graphene with a near 1.05°. In the second place, the atomically smooth surface and insulator properties of hexagonal boron nitride (h-BN) make it an ideal substrate for making graphene devices such as MATBG. This study presents the method to stack graphene with h-BN, from preparing 2D samples to transferring h-BN/graphene to the devices, which is the key step for fabricating MATBG from graphene and h-BN. It was found that using heat-assisted transfer under STM can fabricate the devices successfully. Fabrication of Moiré Superlattices from Exfoliated 2D Materials Supervisor: Berthold JAECK / PHYS Student: CHIU Kwok On / PHYS Course: UROP 2100, Fall With an emphasis on twist bilayer graphene (TBG) and heterostructures of hexagonal boron nitride and monolayer graphene (HBN-MG), this work investigates the Kondo effect in two-dimensional materials. Following Li et al. (2013), who emphasized the Kondo resonance in graphene, we create HBN-MG and TBG stacks and examine their quantum geometry using scanning tunneling microscopy (STM). To examine the Kondo effect, we introduce magnetic impurities by depositing cobalt adatoms. The possible Kondo effect is validated by extensive STM analysis, which reveals significant conductance peaks at the Fermi level. This study adds to our understanding of the quantum properties of 2D materials and their potential applications in modern electronics.
RkJQdWJsaXNoZXIy NDk5Njg=