Microelectronics Research Center, The University of Texas at Austin, 78758, USA.
Phys Rev Lett. 2011 Jul 1;107(1):016803. doi: 10.1103/PhysRevLett.107.016803. Epub 2011 Jun 30.
We investigate the transverse electric field (E) dependence of the ν=0 quantum Hall state (QHS) in dual-gated graphene bilayers in high magnetic fields. The longitudinal resistivity ρ(xx) measured at ν=0 shows an insulating behavior which is strongest in the vicinity of E=0, as well as at large E fields. At a fixed perpendicular magnetic field (B), the ν=0 QHS undergoes a transition as a function of the applied E, marked by a minimum, temperature-independent ρ(xx). This observation is explained by a transition from a spin-polarized ν=0 QHS at small E fields to a valley- (layer-)polarized ν=0 QHS at large E fields. The E field value at which the transition occurs follows a linear dependence on B.
我们研究了在高磁场中双栅石墨烯双层中横向电场（E）对ν=0 量子霍尔态（QHS）的影响。在ν=0 处测量的纵向电阻率 ρ(xx)表现出绝缘行为，在 E=0 附近以及在大 E 场中最强。在固定的垂直磁场 (B)下，ν=0 QHS 随施加的 E 发生变化，表现为最小值，与温度无关的 ρ(xx)。这一观察结果可以解释为，在小 E 场下，自旋极化的 ν=0 QHS 向大 E 场下的谷（层）极化的 ν=0 QHS 转变。发生转变的 E 场值与 B 呈线性关系。
