Gate Controlled Suppression of Weak Localization in Bilayer Graphene due to Proximity Magnetic Effects

The transport properties of bilayer graphene are known to be affected by weak localization at low temperatures. In this study, we use differential conductance mapping to explore the transport properties in bilayer graphene at low temperatures, under conditions for which they are influenced by the proximal of the graphene to a ferromagnet (Co). The low-temperature differential conductance is measured around the Dirac point, with the floating Co “gate” both included in, and absent from, the current path. In the latter case the differential conductance shows the characteristic dip that is known to provide a signature of weak localization. With the Co gate in the current path, however, the differential conductance shows a zero-bias anomaly, implying the suppression of the weak localization at certain energies that are insufficient to cause dephasing of the carriers. The presence and the magnitude of the zero-bias anomaly is depending on the carrier concentration in graphene, making it gate controllable.