Shot noise measurements in the strange metal phase of twisted bilayer graphene

Magic-angle twisted bilayer graphene (MATBG) hosts a wide spectrum of novel electronic phases, that notably include superconductivity, and large linear-in-temperature (T) resistive state (characterized by Planckian dissipation) whose microscopic origin remains under active debate. Competing theories attribute this behavior either to conventional electron–phonon scattering or to a non-Fermi-liquid “strange metal” state analogous to that observed in high-T_c superconductors. Distinguishing between these plausible mechanisms requires probes sensitive to the scattering dynamics of the charge transport. Shot noise measurements, which directly probe current fluctuations arising from charge discreteness and their scattering dynamics, offer a sensitive mean to assess the electron correlation effects. We perform shot noise measurements on MATBG devices to investigate the evolution of the shot noise Fano factor across a range of carrier density and bias regimes and as well as a range of temperatures. A suppression of the Fano factor relative to the Fermi-liquid limit can reveal the breakdown of independent quasiparticle transport and the emergence of collective charge dynamics. By carefully separating thermal and shot noise contributions using cross-correlation techniques, we extract the intrinsic noise characteristics of the system in response to bias. Our measurements provide new insights into electron scattering in the linear-in-T regime of MATBG, offering a microscopic window into novel interaction effects in the flat-bands of MATBG.