Skyrmion dynamics and NMR line shapes in quantum Hall ferromagnets
Skyrmion dynamics and NMR line shapes in quantum Hall ferromagnets
复制标题
量子霍尔铁磁体中的斯格明子动力学和核磁共振谱线形状
DOI：
10.1103/physrevb.61.2749
复制
发表时间：
1999
影响因子：
3.7
通讯作者：
K. Moon
中科院分区：
文献类型：
--
作者：
J. Sinova;S. Girvin;T. Jungwirth;K. Moon
量子霍尔铁磁体中的低能带电激发是自旋取向的拓扑缺陷，称为Skyrmions。最近对量子阱异质结构中核磁共振谱线形状的实验研究表明，在固定的填充因子下，随着温度的降低，从运动上狭窄的谱线形状转变为更宽的“冻结”线形。我们提出了一个Skyrmion扩散模型，它定性地描述了实验观测结果，并给出了Skyrmion输运弛豫时间的时间尺度为$sim 50mrm秒。跃迁的特征是一个中间时间区，我们证明了它对我们模型中的带电自旋织构激发的动力学和子带电子波函数是弱敏感的。我们还表明，谱线形状对通过光泵技术获得的z轴方向的核极化分布非常敏感。
The low energy charged excitations in quantum Hall ferromagnets are topological defects in the spin orientation known as skyrmions. Recent experimental studies on nuclear magnetic resonance spectral line shapes in quantum well heterostructures show a transition from a motionally narrowed to a broader `frozen' line shape as the temperature is lowered at fixed filling factor. We present a skyrmion diffusion model that describes the experimental observations qualitatively and shows a time scale of $\sim 50 \mu{\rm sec}$ for the transport relaxation time of the skyrmions. The transition is characterized by an intermediate time regime that we demonstrate is weakly sensitive to the dynamics of the charged spin texture excitations and the sub-band electronic wave functions within our model. We also show that the spectral line shape is very sensitive to the nuclear polarization profile along the z-axis obtained through the optical pumping technique.