Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν=1 Landau Level Crossing
Robust Quantum Hall Ferromagnetism near a Gate-Tuned ν=1 Landau Level Crossing
复制标题
门调谐 ν=1 Landau 平交道口附近的鲁棒量子霍尔铁磁性
DOI：
10.1103/physrevlett.129.196801
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发表时间：
2022
影响因子：
8.6
通讯作者：
Shayegan, M.
中科院分区：
文献类型：
--
作者：
Ma, Meng K.;Wang, Chengyu;Chung, Y. J.;Pfeiffer, L. N.;West, K. W.;Baldwin, K. W.;Winkler, R.;Shayegan, M.
在低无序的二维电子系统中，当两个自旋或赝自旋相反的朗道能级在费米能级处交叉时，交换能的支配可以导致铁磁的量子霍尔基态，其带隙由交换能确定，并且具有skyrmion作为其激发。这通常通过施加流体静压或单轴应变来实现。我们在这里研究了一个非常高质量，低密度，二维空穴系统，局限于一个30 nm宽的（001）GaAs量子阱，其中两个最低能量的朗道能级可以门调谐交叉填充因子和附近。当我们通过改变空穴密度将交叉点的场位置从的一侧调整到另一侧时，量子霍尔态的能隙仍然非常大，并且只在交叉点附近显示出一个小的下降。差距总体上遵循一个依赖性，预期的交换能量。我们的数据是一致的，一个强大的量子霍尔铁磁体作为基态。
In a low-disorder two-dimensional electron system, when two Landau levels of opposite spin or pseudospin cross at the Fermi level, the dominance of the exchange energy can lead to a ferromagnetic, quantum Hall ground state whose gap is determined by the exchange energy and has skyrmions as its excitations. This is normally achieved via applying either hydrostatic pressure or uniaxial strain. We study here a very high-quality, low-density, two-dimensional hole system, confined to a 30-nm-wide (001) GaAs quantum well, in which the two lowest-energy Landau levels can be gate tuned to cross at and near filling factor. As we tune the field position of the crossing from one side ofto the other by changing the hole density, the energy gap for the quantum Hall state atremains exceptionally large, and only shows a small dip near the crossing. The gap overall follows adependence, expected for the exchange energy. Our data are consistent with a robust quantum Hall ferromagnet as the ground state.