论文标题
有限厚度效应和均匀分数分数量子厅的自旋极化状态
Finite-thickness effect and spin polarization of the even-denominator fractional quantum Hall states
论文作者
论文摘要
在第二个Landau级别（LL）（即5/2和7/2）处的自旋偏振均衡器分数量子大厅（FQH）可能具有遵守非亚伯统计的新型准式粒子激发。然而，尚未对7/2 FQH状态的自旋极化进行实验研究，并且从倾斜场实验中的5/2 FQH状态的自旋极化仍然存在争议。我们使用最低电子温度降至25 mk的压电驱动的样品旋转器，通过精确控制倾斜角度的分辨率小于0.1°，研究了第二个LL中均衡器FQH状态的能量隙。我们观察到5/2、7/2的平面磁场的两个不同的能隙依赖性在第二个LL和第三ll中的第二个LL和重新进入整数量子厅（RIQH）中的其他FQH状态（7/3和8/3）。尽管过渡场因状态而异，但它们相应的平面磁长与样品的量子井厚度相当，这可能是由于有限厚度效应的影响而导致的。在低平面磁场下，在猜想的有限厚度效应开始占主导地位之前，5/2和7/2状态的能量间隙均显示出非核的行为，从而支持自旋极化基态。我们的结果还表明，第三LL中的7/3、8/3 FQH状态和RIQH状态是自旋偏振或部分自旋偏振的。
The spin-polarized even-denominator fractional quantum Hall (FQH) states in the second Landau level (LL), i.e. 5/2 and 7/2, may possess novel quasi-particle excitations obeying non-Abelian statistics. However, the spin polarization of the 7/2 FQH state has not been investigated experimentally and the spin polarization of the 5/2 FQH state from tilted field experiments remains controversial. Using a piezo-driven sample rotator with the lowest electron temperature down to 25 mK, we studied the energy gap of the even-denominator FQH states in the second LL by precise control of the tilted angles with a resolution less than 0.1°. We observed two different energy gap dependences on the in-plane magnetic field for 5/2, 7/2, other FQH states (7/3 and 8/3) in the second LL and reentrant integer quantum Hall (RIQH) states in the third LL. Though the transition fields vary from states, their corresponding in-plane magnetic lengths are comparable to the quantum well thickness of the sample, which may result from the influence of the finite-thickness effect. At low in-plane magnetic fields, before the conjectured finite-thickness effect starts to dominate, the energy gaps of both 5/2 and 7/2 states show a non-decreasing behavior, supporting spin-polarized ground states. Our results also suggest that the 7/3, 8/3 FQH states, and the RIQH states in the third LL are spin-polarized or partially spin-polarized.
