Quantum Transport in Graphene Heterostructures and Few Layer Graphene

This thesis describes low temperature transport experiments designed to study graphene itself and its heterostructures. The external modifications, such as one dimensional periodic potentials, boron nitride (BN) substrate and mechanical strain, will modify the transport properties by changing graphene’s band structure. Graphene with different layers (bilayer, trilayer) will also have different physics. At first, we study the graphene under one dimensional periodic potentials. We use DNA linker to assemble the nanotubes as gate to get a one dimensional periodic potentials. The devices with graphene on top of nanotube gate are studied. The transport controlled by the one dimensional periodic potentials are measured and analyzed. The second part of work is about trilayer graphene aligned withBN with a small rotation angle. The periodic lattice of BN modified the graphene by forming the moir ́e pattern and commensurate state. We studied the effect of electronic interactions between different Dirac points and with magnetic field as well as electric field. Then transport study on the strained bubbles in graphene is reported. We study the pseudo magnetic field formed by the strained graphene. The fourth part of work is aboutvithe hetero-structure of black phosphorus (BP) and graphene. Some interesting anisotropic transport behaviours are introduced from BP to graphene. At the end, an ultra clean bilayer graphene device is reported. In this device, we observe fractional quantum hall effects. The even denominator fractional quantum hall state will be reported first time in an encapsulated bilayer graphene sample