Correlation between resistance fluctuations and temperature dependence of conductivity in graphene

It is known that monolayer graphene has an extraordinarily high intrinsic mobility of the charge carriers. An important complication is the presence of strong mesoscopic resistance fluctuations (MRFs) that, in graphene, persist to relatively high temperatures. These reproducible fluctuations are seen as a function of gate voltage but they are not expected to be seen as a function of temperature T. However, we propose that the monotonic increases or decreases in resistance R(T) that we observe in graphene flakes as T increases from 4.2 K to around 70 K arise from the decay of the magnitude of the MRFs due to progressive dephasing of the interfering scattered electron waves. Using the field effect transistor configuration, we demonstrate that this explanation is correct by measurements of R(T) at different constant gate voltages V(G) tuned to different features of the MRFs observed in R(V(G)) at constant temperature. We find that the T dependence of the MRF magnitude is, surprisingly, best fitted by an exponential decay.