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arXiv 0804.2445cond-mat.mes-hall
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量子霍尔体系中密度不平衡双层空穴的动力学

Dynamics of Density Imbalanced Bilayer Holes in the Quantum Hall Regime

S. Misra, N. C. Bishop, E. Tutuc, M. Shayegan

摘要:

我们报告的磁输运测量双层GaAs空穴系统与不平等的空穴浓度在两个层。在磁场中,一层处于整数量子霍尔态,另一层在费米能处具有体扩展态,后者的纵向和霍尔电阻是滞后的,与先前的测量一致。对于该区域内的固定磁场和低温($T\le$ 350 mK)下,纵向和霍尔电阻的时间演化显示出明显的跳跃,随后是缓慢的弛豫,跳跃序列没有结束。我们的测量结果表明,跳跃同时发生在成对的接触170 $μ$ m分开,并出现涉及的双层的电荷配置的变化。此外,跳跃可以随机或规则的周期发生,排除热波动作为跳跃的可能起源。最后,在保持固定磁场的同时,我们将样品加热到350 mK以上,跳跃消失。在将样品再冷却到低于该温度时,跳跃再次出现,表明跳跃也不是由几乎无耗散的涡电流引起的。

英文摘要:

We report magnetotransport measurements on bilayer GaAs hole systems with unequal hole concentrations in the two layers. At magnetic fields where one layer is in the integer quantum Hall state and the other has bulk extended states at the Fermi energy, the longitudinal and Hall resistances of the latter are hysteretic, in agreement with previous measurements. For a fixed magnetic field inside this region and at low temperatures ($T\le$ 350 mK), the time evolutions of the longitudinal and Hall resistances show pronounced jumps followed by slow relaxations, with no end to the sequence of jumps. Our measurements demonstrate that the jumps occur simultaneously in pairs of contacts 170 $μ$m apart, and appear to involve changes in the charge configuration of the bilayer. In addition, the jumps can occur with either random or regular periods, excluding thermal fluctuations as a possible origin for the jumps. Finally, while remaining at a fixed field, we warm the sample to above 350 mK, where the jumps disappear. Upon recooling the sample below this temperature, the jumps reappear, indicating that the jumps do not result from nearly dissipationless eddy currents either.

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