An exact analytical theory is developed for calculating the diffusion coefficient of charge carriers in strongly anisotropic disordered solids with one-dimensional hopping transport mode for any dependence of the hopping rates on space and energy. So far such a theory existed only for calculating the carrier mobility. The dependence of the diffusion coefficient on the electric field evidences a linear, non-analytic behavior at low fields for all considered models of disorder. The mobility, on the contrary, demonstrates a parabolic, analytic field dependence for a random-barrier model, being linear, non-analytic for a random energy model. For both models the Einstein relation between the diffusion coefficient and mobility is proven to be violated at any finite electric field. The question on whether these non-analytic field dependences of the transport coefficients and the concomitant violation of the Einstein's formula are due to the dimensionality of space or due to the considered models of disorder is resolved in the following paper [Nenashev et al., arXiv:0912.3169], where analytical calculations and computer simulations are carried out for two- and three-dimensional systems.
Exact multi-electronic electron-concentration dependent ground-states for disordered two-dimensional two-band systems in presence of disordered hoppings and finite on-site random interactions
Integral Variable Range Hopping for Modeling Electrical Transport in Disordered Systems
School of Physics, Peking University(北京大学物理学院);Interdisciplinary Institute of Light-Element Quantum Materials and Research Center for Light-Element Advanced Materials, Peking University(北京大学轻元素量子材料交叉研究所和轻元素先进材料研究中心);State Key Laboratory of Artificial Microstructure and Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, Peking University(北京大学人工微结构和介观物理国家重点实验室和纳米光电前沿科学中心)
We study the fate of many-body localization (MBL) in the presence of long-range hopping ($\sim 1/r^σ$) in a system subjected to an electric field (static and time-periodic) along with a slowly-varying aperiodic potential. We show that the MBL in the static electric-field model is robust against arbitrary long-range hopping in sharp contrast to other disordered models, where MBL is killed by sufficiently long-range hopping. Next, we show that the drive-induced phenomena associated with an ac square wave electric field are also robust against long-range hopping. Specifically, we obtain drive-ind…
Gate-modulated thermopower of disordered nanowires: II. Variable-range hopping regime
我们研究了场效应晶体管结构中无序纳米线的热电势。在致力于弹性相干区的第一篇论文(Bosisio R.,弗勒里湾Pichard J. - L. 2014 \textit{New J. Phys.} \textbf{16} 035004),我们在此考虑在较高温度下发生的非弹性活化状态。在电荷传输由声子热辅助的情况下(莫特可变范围跳跃制度),我们使用最近由Jiang等人改编的Miller-Abrahams随机电阻网络模型。这种方法以前用于研究大部分的纳米线杂质带扩展研究其边缘。在这个限制,我们表明,典型的热电势大大增强,达到更大的值,$10\, k_B/e \sim 1\, \mathrm{mV\,K}^{-1}$和表现出非平凡的行为作为温度的函数。由Zvyagin延伸到无序纳米线的渗滤理论,使我们能够占主要观察到的边缘行为的热电。
Hopping conduction in strong electric fields: Negative differential conductivity
从理论上研究了强电场对跳跃电导率的影响。Monte-Carlo计算机模拟表明,Nguyen和Shklovskii [Solid State Commun. 38,99(1981)]提供了在非常高的电场和与定域位点的浓度相比低浓度的载流子的限制下以及在载流子的相对浓度等于0.5时的跳跃传输的准确描述。在0.1和0.5之间的载体的中间浓度的计算机模拟证据从现有的分析理论的结果的基本偏差。Nguyen和Shklovskii的理论还预测了在高电场下的负微分跳跃电导率。我们的数值计算定性地证实了这一预测。然而,场的依赖性的载流子的漂移速度的数值获得的本质上不同于迄今为止的预测。分析理论得到进一步发展,使其与数值计算结果的一致性得到实质性的改善。
We study an experimentally feasible system of strongly correlated bosons with random hoppings, described by the infinite-range Bose-Hubbard model on a lattice with hopping integrals given by independent random variables of Gaussian distribution with non-zero mean. We solve this quantum model in the thermodynamic limit, employing the replica method and the Trotter-Suzuki formula. We find and describe a superglass phase that emerges at the interface between glass and superfluid phases. Both glassy and long-range orderings are present in the superglass and compete with each other, as revealed by …
Nodal semimetals (e.g. Dirac, Weyl and nodal-line semimetals, graphene, etc.) and systems of pinned particles with power-law interactions (trapped ultracold ions, nitrogen defects in diamonds, spins in solids, etc.) are presently at the centre of attention of large communities of researchers working in condensed-matter and atomic, molecular and optical physics. Although seemingly unrelated, both classes of systems are abundant with novel fundamental thermodynamic and transport phenomena. In this paper, we demonstrate that low-energy field theories of quasiparticles in semimetals may be mapped …
We study two coupled 3D lattices, one of them featuring uncorrelated on-site disorder and the other one being fully ordered, and analyze how the interlattice hopping affects the localization-delocalization transition of the former and how the latter responds to it. We find that moderate hopping pushes down the critical disorder strength for the disordered channel throughout the entire spectrum compared to the usual phase diagram for the 3D Anderson model. In that case, the ordered channel begins to feature an effective disorder also leading to the emergence of mobility edges but with higher as…