Spin-Polarized to Valley-Polarized Transition in Graphene Bilayers atν=0in High Magnetic Fields

Seyoung Kim, Kayoung Lee, E. Tutuc
2011 Physical Review Letters  
We investigate the transverse electric field ($E$) dependence of the $\nu$=0 quantum Hall state (QHS) in dual-gated graphene bilayers in high magnetic fields. The longitudinal resistivity ($\rho_{xx}$) measured at $\nu$=0 shows an insulating behavior which is strongest in the vicinity of $E$=0, and at large $E$-fields. At a fixed perpendicular magnetic field ($B$), the $\nu$=0 QHS undergoes a transition as a function of $E$, marked by a minimum, temperature-independent $\rho_{xx}$. This
more » ... {xx}$. This observation is explained by a transition from a spin polarized $\nu$=0 QHS at small $E$-fields, to a valley (layer) polarized $\nu$=0 QHS at large $E$-fields. The $E$-field value at which the transition occurs has a linear dependence on $B$
doi:10.1103/physrevlett.107.016803 pmid:21797563 fatcat:n2p22kmzgvgohasszy5jtjuqqm