arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.06001cond-mat.dis-nn
收藏

低维幂律跳跃Anderson模型的尾态和反常局域化跃迁

Tail states and unusual localization transition in low-dimensional Anderson model with power-law hopping

Konstantin S. Tikhonov, Alexey S. Ioselevich, Mikhail V. Feigel'man

摘要:

在$d < β< 3d/2$条件下,研究了具有振幅$J(r) \propto - r^{-β}$和低维$d=1,2$中局域高斯无序的确定性幂律量子跳跃模型.我们展示了不寻常的组合指数下降的密度的“尾态”和本地化-离域过渡(作为功能的无序强度$w$)有关的一个小的(在热力学极限消失)分数的本征态。在亚临界无序状态下,$w < w_c$离域本征态与强局域本征态在同一能量窗口内共存,离域本征态的能量接近裸带边。在较高的无序度$w > w_c$,所有本征态都是局域的。在较宽的参数范围内,态密度$ν(E)$以简单的指数规律$ ν(E) = ν_0 e^{E/E_0} $衰减到尾区$E <0$,而特征能量$E_0$在边缘局域化跃迁时变化平缓.我们开发简单的分析理论,描述$E_0$依赖于幂律指数$β$,维数$d$和无序强度$W$,并比较其预测与精确的对角化结果。在裸“导带”内的低能量下,由于$d=1,2$处的强量子干涉,所有本征态都被局域化;然而,局域化长度随着能量的减小而快速增长,与通常的薛定谔方程的局域无序情况相反。

英文摘要:

We study deterministic power-law quantum hopping model with an amplitude $J(r) \propto - r^{-β}$ and local Gaussian disorder in low dimensions $d=1,2$ under the condition $d < β< 3d/2$. We demonstrate unusual combination of exponentially decreasing density of the "tail states" and localization-delocalization transition (as function of disorder strength $w$) pertinent to a small (vanishing in thermodynamic limit) fraction of eigenstates. At sub-critical disorder $w < w_c$ delocalized eigenstates with energies near the bare band edge co-exist with a strongly localized eigenstates in the same energy window. At higher disorder $w > w_c$ all eigenstates are localized. In a broad range of parameters density of states $ν(E)$ decays into the tail region $E <0$ as simple exponential, $ ν(E) = ν_0 e^{E/E_0} $, while characteristic energy $E_0$ varies smoothly across edge localization transition. We develop simple analytic theory which describes $E_0$ dependence on power-law exponent $β$, dimensionality $d$ and disorder strength $W$, and compare its predictions with exact diagonalization results. At low energies within the bare "conduction band", all eigenstates are localized due to strong quantum interference at $d=1,2$; however localization length grows fast with energy decrease, contrary to the case of usual Schrodinger equation with local disorder.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑