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arXiv 1807.00871cond-mat.str-elcond-mat.mes-hall
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第二朗道能级中的电子-电子相互作用和成对向列量子相变

Electron-Electron Interactions and the Paired-to-Nematic Quantum Phase Transition in the Second Landau Level

K. A. Schreiber, N. Samkharadze, G. C. Gardner, Y. Lyanda-Geller, M. J. Manfra, L. N. Pfeiffer, K. W. West, G. A. Csáthy

摘要:

尽管它在强关联系统中普遍存在,成对和非成对的基态的竞争仍然知之甚少。最近,在填充因子为$ν=5/2$的二维电子气中报道了这种竞争。在此填充因子下,观察到从成对分数量子霍尔态到量子霍尔态的压力诱导量子相变。在这里,我们表明,压力诱导的配对到双跃迁也发展在$ν=7/2$,因此证明了这种转变在第二轨道朗道能级的两个自旋分支。然而,我们发现,压力不是控制这种转变的唯一参数。事实上,与在压力下观察到的情况一致的基态也在环境压力下测量的样品中发展,但是其中电子-电子相互作用被调整到接近其在量子临界点的值。我们的实验表明,电子-电子相互作用在驱动配对到双极跃迁中起着至关重要的作用。

英文摘要:

In spite of its ubiquity in strongly correlated systems, the competition of paired and nematic ground states remains poorly understood. Recently such a competition was reported in the two-dimensional electron gas at filling factor $ν=5/2$. At this filling factor a pressure-induced quantum phase transition was observed from the paired fractional quantum Hall state to the quantum Hall nematic. Here we show that the pressure induced paired-to-nematic transition also develops at $ν=7/2$, demonstrating therefore this transition in both spin branches of the second orbital Landau level. However, we find that pressure is not the only parameter controlling this transition. Indeed, ground states consistent with those observed under pressure also develop in a sample measured at ambient pressure, but in which the electron-electron interaction was tuned close to its value at the quantum critical point. Our experiments suggest that electron-electron interactions play a critical role in driving the paired-to-nematic transition.

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