اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHopping conduction in strongly insulating states of a diffusive bent quantum Hall junction
106
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Transport studies of a bent quantum Hall junction at integer filling factors show strongly insulating states at higher fields. In this paper we analyze the strongly insulating behavior as a function of temperature T and dc bias V, in order to classify the localization mechanisms responsible for the insulating state. The temperature dependence suggests a crossover from activated nearest-neighbor hopping at higher T to variable-range hopping conduction at lower T. The base temperature electric field dependence is consistent with 1D variable-range hopping conduction. We observe almost identical behavior at filling factors 1 and 2, and discuss how the bent quantum Hall junction conductance appears to be independent of the bulk spin state. Various models of 1D variable-range hopping which either include or ignore interactions are compared, all of which are consistent with the basic model of disorder coupled counter-propagating quantum Hall edges.
قيم البحث
اقرأ أيضاً
We study the electronic transport across an electrostatically-gated lateral junction in a HgTe quantum well, a canonical 2D topological insulator, with and without applied magnetic field. We control carrier density inside and outside a junction regio
n independently and hence tune the number and nature of 1D edge modes propagating in each of those regions. Outside the 2D gap, magnetic field drives the system to the quantum Hall regime, and chiral states propagate at the edge. In this regime, we observe fractional plateaus which reflect the equilibration between 1D chiral modes across the junction. As carrier density approaches zero in the central region and at moderate fields, we observe oscillations in resistance that we attribute to Fabry-Perot interference in the helical states, enabled by the broken time reversal symmetry. At higher fields, those oscillations disappear, in agreement with the expected absence of helical states when band inversion is lifted.
The temperature dependence of the electrical transport of a individual tin oxide nanobelt was measured, in darkness, from 400 to 5K. We found four intrinsic electrical transport mechanisms through the nanobelt. It starts with Thermal-Activation Condu
ction between 400 and 314K, Nearest-Neighbor Hopping conduction between 268 and 115K, and Variable Range Hopping conduction below 58K, with a crossover from the 3D-Mott to the 3D-Efros-Shklovskii regime at 16K. We claim that this sequence reveal the three-dimensional nature of the electrical transport in the SnO2 nanobelts, even they are expected to behave as one-dimensional systems.
We report on the fabrication and transport studies of a single-layer graphene p-n junction. Carrier type and density in two adjacent regions are individually controlled by electrostatic gating using a local top gate and a global back gate. A function
alized Al203 oxide that adheres to graphene and does not significantly affect its electronic properties is described. Measurements in the quantum Hall regime reveal new plateaus of two-terminal conductance across the junction at 1 and 3/2 times the quantum of conductance, e2/h, consistent with theory.
We investigate the emergence of long-range electron hopping mediated by cavity vacuum fields in disordered quantum Hall systems. We show that the counter-rotating (anti-resonant) light-matter interaction produces an effective hopping between disorder
ed eigenstates within the last occupied Landau band. The process involves a number of intermediate states equal to the Landau degeneracy: each of these states consists of a virtual cavity photon and an electron excited in the next Landau band with the same spin. We study such a cavity-mediated hopping mechanism in the dual presence of a random disordered potential and a wall potential near the edges, accounting for both paramagnetic coupling and diamagnetic renormalization. We determine the cavity-mediated scattering rates, showing the impact on both bulk and edge states. The effect for edge states is shown to increase when their energy approaches the disordered bulk band, while for higher energy the edge states become asymptotically free. We determine the scaling properties while increasing the Landau band degeneracy. Consequences on the quantum Hall physics and future perspectives are discussed.
We have observed shot noise in the hopping conduction of two dimensional carriers confined in a p-type SiGe quantum well at a temperature of 4K. Moreover, shot noise is suppressed relative to its ``classical value 2eI by an amount that depends on the
length of the sample and carrier density, which was controlled by a gate voltage. We have found a suppression factor to the classical value of about one half for a 2 $mu$m long sample, and of one fifth for a 5 $mu$m sample. In each case, the factor decreased slightly as the density increased toward the insulator-metal transition. We explain these results in terms of the characteristic length ($simeq 1mu$m in our case) of the inherent inhomogeneity of hopping transport.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
