Electron Tunneling Studies of Variable Range Hopping Conductors

小行星9316803 技术摘要：许多几乎不在金属-绝缘体转变的绝缘侧上的材料通过可变范围跳跃（弗赫）导电，其中电导率取决于温度，如exp（T0/T）1/n，对于整数n 1。 虽然弗赫由非相互作用的电子是很好地理解，最近的实验表明，弗赫在低温下在磁扰动的存在下导致新的和意想不到的现象，包括一个新的自旋电荷耦合准粒子的可能性。 计划在低温和高磁场下使用电子隧穿和磁输运实验来研究弗赫导体中的多体态密度和元激发谱。 我们的目标是直接测量建议的能隙结构推断电导率数据，并阐明磁散射对跳跃传导的影响。 非技术摘要：凝聚态物理学中的一个基本问题与固体中的导电机制有关。 虽然对普通金属和半导体的理解已经高度发展，但许多材料表现出不寻常的，通常知之甚少的电学行为。 一种常见的非常规导电形式被称为变程跳变（弗赫）. 由于许多不同的技术上重要的固体是弗赫导体，这是具有实际意义的发展更深刻的物理理解这一过程。 最近的实验表明，弗赫传导可以产生复杂和完全出乎意料的行为。 为了阐明这种导电性的基本原理，建议直接研究不同弗赫导体中载流子的微观性质。 ***

9316803 Lee Technical abstract: Many materials that are barely on the insulating side of a metal-insulator transition conduct electricity by variable range hopping (VRH), for which the conductivity depends on temperature as exp(T0/T)1/n, for integer n 1. While VRH by non-interacting electrons is well understood, recent experiments have shown that VRH at low temperatures in the presence of magnetic perturbations leads to new and unexpected phenomena, including the possibility of a new spin-charge coupled quasiparticle. It is planned to investigate the many-body density-of-states and elementary excitation spectrum in VRH conductors using electron tunneling and magneto transport experiments at low temperatures and high magnetic fields. The goal is to directly measure the proposed energy gap structure inferred from conductivity data and to elucidate the effects of magnetic scattering on hopping conduction. Non-technical abstract: A fundamental problem in condensed matter physics is concerned with the mechanism of electrical conduction in a solid. While the understanding of common metals and semiconductors is highly developed, many materials exhibit unusual, often poorly understood electrical behavior. A commonly observed form of unconventional electrical conduction is known as variable- range hopping (VRH). Since many diverse technologically important solids are VRH conductors, it is of practical importance to develop a more profound physical understanding of this process. Recent experiments have shown that VRH conduction can yield complex and completely unexpected behavior. In order to elucidate the fundamental principles which underlie this electrical conductiom it is proposed to study directly rhe microscopic properties of the charge carriers in different VRH conductors. ***