New phase transition between partially and fully polarized quantum Hall states with charge and spin gaps at nu = 2/3.
New phase transition between partially and fully polarized quantum Hall states with charge and spin gaps at nu = 2/3.
复制标题
部分和完全极化的量子霍尔态之间的新相变，电荷和自旋间隙为 nu = 2/3。
DOI：
10.1103/physrevlett.87.136801
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发表时间：
2001
影响因子：
8.6
通讯作者：
L. Lévy
中科院分区：
文献类型：
--
作者：
N. Freytag;Y. Tokunaga;M. Horvatić;C. Berthier;M. Shayegan;L. Lévy
在填充因子$\nu = 2/3$的分数量子霍尔态附近，通过核磁共振测量了限制在GaAs/GaAlAs多量子阱中的二维电子气的平均电子自旋极化率$\rho$。在这个填充因子之上（$2/3\leq\nu<0.85$），观察到强烈的去极化现象，对应于每增加一个磁通量子有两次自旋翻转。在$\nu = 2/3$时观察到极化最显著的行为，当塞曼能与库仑能之比增加到高于临界值$\eta_{c}=\Delta_{Z}/\Delta_{C}=0.0185$时，可以驱动从部分极化（$\rho\approx3/4$）到完全极化（$\rho = 1$）状态的量子相变。
The average electron spin polarization Rho of a two-dimensional electron gas confined in GaAs/GaAlAs multiple quantum wells was measured by NMR near the fractional quantum Hall state with filling factor nu = 2/3. Above this filling factor (2/3< or = nu < 0.85), a strong depolarization is observed corresponding to two spin flips per additional flux quantum. The most remarkable behavior of the polarization is observed at nu = 2/3, where a quantum phase transition from a partially polarized (Rho approximately 3/4) to a fully polarized (Rho = 1) state can be driven by increasing the ratio between the Zeeman and the Coulomb energy above a critical value eta(c) = Delta(Z)/Delta(C) = 0.0185.