The quantum Hall ferromagnet at high filling factors: A magnetic field induced Stoner transition
The quantum Hall ferromagnet at high filling factors: A magnetic field induced Stoner transition
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高填充因子下的量子霍尔铁磁体：磁场诱导斯托纳转变
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
G. Hill
中科院分区：
文献类型：
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作者：
B. Piot;D. Maude;M. Henini;Z. Wasilewski;K. Friedland;R. Hey;K. Ploog;A. Toropov;R. Airey;G. Hill
本文研究了一系列${mathrm{Al}}_{x}{mathrm{Ga}}_{1 ensuremath {-}x}mathrm{As}闪烁{GaAs}$异质结和量子威尔斯阱中整数量子霍尔效应中的自旋分裂。磁阻测量在mK温度下进行，以表征电子态密度并估计多体相互作用的强度。没有自由参数的简单模型正确地预测了观察自旋分裂所需的磁场，证实了自旋分裂的出现是翻转自旋的无序诱导能量成本与与极化状态相关的交换能量增益之间竞争的结果。在这个模型中，单粒子塞曼能量不起作用，因此在最高占据的朗道能级出现这种量子霍尔铁磁体也可以被认为是磁场诱导的斯通纳跃迁。
Spin splitting in the integer quantum Hall effect is investigated for a series of ${mathrm{Al}}_{x}{mathrm{Ga}}_{1ensuremath{-}x}mathrm{As}∕mathrm{GaAs}$ heterojunctions and quantum wells. Magnetoresistance measurements are performed at mK temperature to characterize the electronic density of states and estimate the strength of many body interactions. A simple model with no free parameters correctly predicts the magnetic field required to observe spin splitting, confirming that the appearance of spin splitting, is a result of a competition between the disorder induced energy cost of flipping spins and the exchange energy gain associated with the polarized state. In this model, the single particle Zeeman energy plays no role, so that the appearance of this quantum Hall ferromagnet in the highest occupied Landau level can also be thought of as a magnetic field induced Stoner transition.