Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing
Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing
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DOI：
10.1103/physrevlett.125.067404
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发表时间：
2020-08-07
影响因子：
8.6
通讯作者：
Wegscheider, W.
中科院分区：
文献类型：
--
作者：
Lupatini, M.;Knuppel, P.;Wegscheider, W.
当朗道能级(LLS)在量子霍尔区的费米能级附近简并时，相互作用效应可以极大地改变电子的基态。我们研究了二维空穴气体中形成的量子霍尔铁磁体，其填充因子v=1位于空穴价带中的一个交叉点附近。强耦合区的腔谱使我们能够光学地提取二维空穴气体的自旋极化。通过分析这种极化作为空穴密度和磁场的函数，我们观察到铁磁体的自旋翻转。此外，远离v=1的去极化在接近L1交叉时加速。这表明当有效塞曼能量在L1交叉处消失时，天空米子激发的大小增加了。
When Landau levels (LLs) become degenerate near the Fermi energy in the quantum Hall regime, interaction effects can drastically modify the electronic ground state. We study the quantum Hall ferromagnet formed in a two-dimensional hole gas around the LL filling factor v = 1 in the vicinity of a LL crossing in the heave-hole valence band. Cavity spectroscopy in the strong-coupling regime allows us to optically extract the spin polarization of the two-dimensional hole gas. By analyzing this polarization as a function of hole density and magnetic field, we observe a spin flip of the ferromagnet. Furthermore, the depolarization away from v = 1 accelerates close to the LL crossing. This is indicative of an increase in the size of skyrmion excitations as the effective Zeeman energy vanishes at the LL crossing.