Limitations to Carrier Mobility and Phase-Coherent Transport in Bilayer Graphene

Abstract

We present transport measurements on high-mobility bilayer graphene fully encapsulated in hexagonal boron nitride. We show two terminal quantum Hall effect measurements which exhibit full symmetry broken Landau levels at low magnetic fields. From weak localization measurements, we extract gate-tunable phase coherence times \(\tau_{\phi}\) as well as the inter- and intra-valley scattering times \(\tau_i\) and \(\tau_*\). While \(\tau_{\phi}\) is in qualitative agreement with an electron-electron interaction mediated dephasing mechanism, electron spin-flip scattering processes are limiting \(\tau_{\phi}\) at low temperatures. The analysis of \(\tau_i\) and \(\tau_*\) points to local strain fluctuation as the most probable mechanism for limiting the mobility in high-quality bilayer graphene.