学术报告

学术活动

学术报告
03/12 2021
  • Title题目 (Seminar) Level statistics and Anderson delocalization in two-dimensional granular materials
  • Speaker报告人
  • Date日期
  • Venue地点
  • Abstract摘要

    CAS Key Laboratory of Theoretical Physics

    Institute of Theoretical Physics

    Chinese Academy of Sciences

    Seminar

    Title

    题目

    Level statistics and Anderson delocalization in two-dimensional granular materials

    Speaker

    报告人

    张玲

    Affiliation

    所在单位

    中南大学

    Date

    日期

    2021年3月12日周五16:00

    Venue

    地点

    腾讯会议 (ID:177 514 448)

    Contact Person

    所内联系人

    金瑜亮

    Abstract

    摘要

    Contrary to the theoretical predictions of one-parameter scaling theory, that all waves in two-dimensional disordered materials are localized, Anderson localization is observed only for sufficiently high frequencies in an isotropically jammed two-dimensional disordered granular packing of photoelastic disks. More specifically, we have performed an experiment in analyzing the level statistics of normal mode vibrations. We find that the level[1]distance distribution obeys Gaussian-Orthogonal-Ensemble (GOE) statistics of the Wigner-Dyson classification, in the low-frequency (boson-peak) and intermediate frequency regime, whereas in the high-frequency regime Poisson statistics are observed. This means that at the low and intermediate frequencies we have delocalized modes, and only at the very high frequencies localized modes exist. Evaluating the system-size dependence of the delocalization-localization crossover frequency we obtain evidence for a true transition with a mobility edge at 80% of the Debye frequency and a value of the critical correlation-length exponent ν ~1.66 being similar to that of the three-dimensional electronic Anderson model. We argue that for force-constant disorder one-parameter scaling might not be applicable.

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