Piot B A, Desrat W, Maude D K, Kazazis D, Cavanna A, Gennser U
Laboratoire National des Champs Magnétiques Intenses, LNCMI-CNRS-UGA-UPS-INSA-EMFL, F-38042 Grenoble, France.
Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France.
Phys Rev Lett. 2016 Mar 11;116(10):106801. doi: 10.1103/PhysRevLett.116.106801. Epub 2016 Mar 9.
We report on an absolute measurement of the electronic spin polarization of the ν=1 integer quantum Hall state. The spin polarization is extracted in the vicinity of ν=1 (including at exactly ν=1) via resistive NMR experiments performed at different magnetic fields (electron densities) and Zeeman energy configurations. At the lowest magnetic fields, the polarization is found to be complete in a narrow region around ν=1. Increasing the magnetic field (electron density) induces a significant depolarization of the system, which we attribute to a transition between the quantum Hall ferromagnet and the Skyrmion glass phase theoretically expected as the ratio between Coulomb interactions and disorder is increased. These observations account for the fragility of the polarization previously observed in high mobility 2D electron gas and experimentally demonstrate the existence of an optimal amount of disorder to stabilize the ferromagnetic state.
我们报告了对ν = 1整数量子霍尔态电子自旋极化的绝对测量。通过在不同磁场（电子密度）和塞曼能配置下进行的电阻核磁共振实验，在ν = 1附近（包括恰好ν = 1时）提取自旋极化。在最低磁场下，发现在ν = 1周围的狭窄区域极化是完全的。增加磁场（电子密度）会导致系统显著去极化，我们将其归因于量子霍尔铁磁体和斯格明子玻璃相之间的转变，理论上预期随着库仑相互作用与无序度之比的增加会发生这种转变。这些观察结果解释了先前在高迁移率二维电子气中观察到的极化的脆弱性，并通过实验证明了存在一个稳定铁磁态的最佳无序量。
