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arXiv 0711.2668cond-mat.str-elcond-mat.dis-nn
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量子电子玻璃中的集体模和电子辅助跃迁

Collective modes in quantum electron glasses and electron-assisted hopping

Markus Mueller, Lev B. Ioffe

摘要:

我们研究了d ≥ 2维强库仑相互作用下Anderson绝缘体中的电子输运。在金属-绝缘体相变附近,单粒子局域化长度远大于粒子间距离,相互作用导致强关联的量子玻璃相。即使单粒子激发是局域的,系统是绝缘的,也有集体电子模式保持离域到参数小的能量。这些集体激发作为一个连续的浴,可以提供可变范围跳跃传输的激活能。这就避免了当只存在离散的粒子-空穴激发时所产生的能量守恒问题。与弱的、依赖于材料的声子辅助跳跃机制相反,电子浴的激活导致了几乎普遍的埃夫罗斯-什克洛夫斯基电导的前因子e^2/h,这在最近的许多实验中都观察到了。

英文摘要:

We study electronic transport in Anderson insulators with strong Coulomb interactions in dimensions d>=2. Close to the metal insulator transition where the single particle localization length is much larger than interparticle-distance, the interactions lead to a strongly correlated quantum glass phase. Even though single particle excitations are localized and the system is insulating, there are collective electronic modes which remain delocalized down to parametrically small energies. These collective excitations serve as a continuous bath which can provide the activation energy for variable range hopping transport. This circumvents the energy conservation problem arising when only discrete particle-hole excitations are present. In contrast to the weak and material-dependent phonon-assisted hopping mechanism, the activation by an electronic bath leads to a nearly universal prefactor e^2/h of the Efros-Shklovskii conductance, as is observed in many recent experiments.

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。

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