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arXiv 1102.4701cond-mat.dis-nn
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安德森局域化跃迁的临界Dyson分级模型

A critical Dyson hierarchical model for the Anderson localization transition

Cecile Monthus, Thomas Garel

摘要:

安德森局域化的戴森分层模型,包含非随机分层跳跃和随机的在位能量,自从Bovier [J. Stat. Phys.59,745(1990)],结论是该模型总是处于定域相。在这里,我们表明,如果一个引入交替的符号沿层次的跳跃(而不是选择所有的跳跃相同的符号),它是可能达到一个安德森局域化的临界点,提出多重分形本征函数和中间谱统计。这个模型的优点是可以写出一些观测量的精确重整化方程。特别地,我们得到了重整化在位能量对于精确不动点具有Cauchy分布。这种重整化分析的另一个输出是临界本征函数的典型指数总是$α_{typ}=2$,与无序强度无关。我们给出了关于随机现场能量的盒分布和柯西分布的整个多重分形谱$f(α)$和水平统计的可压缩性$χ$的数值结果。我们讨论的相似性和差异,最近推出的超度量随机矩阵的合奏Fyodorov,Ossipov和Rodriguez [J.统计。L12001(2009)]。

英文摘要:

A Dyson hierarchical model for Anderson localization, containing non-random hierarchical hoppings and random on-site energies, has been studied in the mathematical literature since its introduction by Bovier [J. Stat. Phys. 59, 745 (1990)], with the conclusion that this model is always in the localized phase. Here we show that if one introduces alternating signs in the hoppings along the hierarchy (instead of choosing all hoppings of the same sign), it is possible to reach an Anderson localization critical point presenting multifractal eigenfunctions and intermediate spectral statistics. The advantage of this model is that one can write exact renormalization equations for some observables. In particular, we obtain that the renormalized on-site energies have the Cauchy distributions for exact fixed points. Another output of this renormalization analysis is that the typical exponent of critical eigenfunctions is always $α_{typ}=2$, independently of the disorder strength. We present numerical results concerning the whole multifractal spectrum $f(α)$ and the compressibility $χ$ of the level statistics, both for the box and the Cauchy distributions of the random on-site energies. We discuss the similarities and differences with the ensemble of ultrametric random matrices introduced recently by Fyodorov, Ossipov and Rodriguez [J. Stat. Mech. L12001 (2009)].

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