多子带阱中$ρ_{xx}$环状结构的多体效应
Many-body effects on the $ρ_{xx}$ ringlike structures in two-subband wells
摘要：
二维电子气的纵向电阻率$ρ_{xx}$的阱中形成的两个子带显示环状结构时，绘制在密度-磁场图，由于交叉的自旋分裂朗道能级（LLS）从不同的子带。利用自旋密度泛函理论和线性响应，我们研究了这些结构的形状和自旋极化作为温度和磁场倾斜角的函数。我们发现（i）由于量子霍尔铁磁相变，一些环在足够低的温度下“断裂”，从而在内部表现出高度的自旋极化（$\sim 50 $ %），与Zhang \textit{et al.} [Phys.Rev.Lett. { \bf 98}，246802（2007）]，和（ii）对于增加倾斜角，由于LL间耦合和交换相关（XC）效应引起的反交叉之间的相互作用导致环在某个临界角$θ_c$处的坍塌，与Guo \textit{et al.}的数据[Phys. Rev. B { \bf 78}，233305（2008）]一致。
英文摘要：
The longitudinal resistivity $ρ_{xx}$ of two-dimensional electron gases formed in wells with two subbands displays ringlike structures when plotted in a density--magnetic-field diagram, due to the crossings of spin-split Landau levels (LLs) from distinct subbands. Using spin density functional theory and linear response, we investigate the shape and spin polarization of these structures as a function of temperature and magnetic-field tilt angle. We find that (i) some of the rings "break" at sufficiently low temperatures due to a quantum Hall ferromagnetic phase transition, thus exhibiting a high degree of spin polarization ($\sim 50 $%) within, consistent with the NMR data of Zhang \textit{et al.} [Phys. Rev. Lett. {\bf 98}, 246802 (2007)], and (ii) for increasing tilting angles the interplay between the anticrossings due to inter-LL couplings and the exchange-correlation (XC) effects leads to a collapse of the rings at some critical angle $θ_c$, in agreement with the data of Guo \textit{et al.} [Phys. Rev. B {\bf 78}, 233305 (2008)].
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