Temperature dependance of the tunneling density of states in sub-micron   planar metal / oxide / graphene junctions
  We present tunneling measurements of sub-micron metal/insulator/graphene planar tunnel junctions up to room temperature. We observe a gate independent gap, as previously observed only by low temperature STM[Y. Zhang et al., Nat. Phys. 4, 627 (2008)]. No gap appears at temperatures above 150K, which is four times smaller than the theoretically expected $T_{c}$, from the accepted mean field model[T. O. Wehling et al. Phys. Rev. Lett. 101, 216803 (2008)]. We show that taking into account an additional vibrational effect of out-of-plane phonon soft modes the gap may disappear from the measurements at temperatures much lower than the calculated $T_{c}$. 
Shay Hacohen-Gourgy, Itay Diamant, Boaz Almog, Yoni Dubi, G Deutscher
cond-mat.str-el cond-mat.mes-hall