Micrometer-scale ballistic transport in encapsulated graphene at room   temperature
  Devices made from graphene encapsulated in hexagonal boron-nitride exhibit pronounced negative bend resistance and an anomalous Hall effect, which are a direct consequence of room-temperature ballistic transport on a micrometer scale for a wide range of carrier concentrations. The encapsulation makes graphene practically insusceptible to the ambient atmosphere and, simultaneously, allows the use of boron nitride as an ultrathin top gate dielectric. 
A. S. Mayorov, R. V. Gorbachev, S. V. Morozov, L. Britnell, R. Jalil,   L. A. Ponomarenko, P. Blake, K. S. Novoselov, K. Wat...
cond-mat.mtrl-sci cond-mat.mes-hall