Shot Noise in Magic-Angle Twisted Bilayer Graphene

Magic-angle twisted bilayer graphene (MATBG) is a known superconductor that exhibits linear resistivity in a wide range of temperatures. This property of unconventional superconductivity makes it an ideal sample for studying strange metal phase behavior. To examine the origin of the linear-in-T resistivity and its possible connection to strange metal phase in MATBG, we focus on the current-carrying excitations. Shot noise, which arises from the discrete nature of charge carriers, can provide information about the charge quantization and interactions between charge carriers. In order to measure the shot noise, the MATBG device is cooled to 4K in a ⁴He Dewar, then a voltage bias is applied through a cryostat to drive the charge carriers. The resulting signal is passed to two parallel low noise amplifiers in a room temperature Faraday cage. At high frequencies, electronic noise is filtered out, and we reduce the thermal noise floor to isolate the shot noise. We compute the cross correlation power spectrum density to analyze the noise. I will discuss how the characterization of these shot noise measurements gives further insight into electron scattering dynamics in moire pattern structures, such as MATBG.