Organic Conductors and Superconductors: New Directions in the Solid State

MRS Bulletin ◽  
1993 ◽  
Vol 18 (8) ◽  
pp. 29-37 ◽  
Author(s):  
J.S. Brooks
Keyword(s):  
Magnetic Field ◽  
Quantum Hall ◽  
Energy Scale ◽  
Energy Bands ◽  
Organic Salts ◽  
Semiconductor Physics ◽  
Low Dimensions ◽  
New Directions ◽  
One Step ◽  
Present Understanding

In single-crystal organic salts, we find a keen competition between superconducting, magnetic, insulating, and metallic states. The physics of these materials is further enriched by the sensitivity of these states to pressure, temperature, chemical formulation, and magnetic field. A growing international community of scientists have turned their attention to these materials, and are applying the techniques and theories of metal and semiconductor physics to probe these new systems. In this article we will explore these materials. We will discover that these materials have given us many new things: a renaissance in fermiology, new high-magnetic-field states of matter, a bulk quantum Hall effect, new challenges in the calculation of energy bands on a small energy scale, and elusive behavior which seems one step away from our present understanding of physics in low dimensions. Electron correlations probably play an important role in determining the phenomena, and should be considered in more microscopic theoretical treatments of these systems.

scholarly journals Topological gaps by twisting

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Matheus I. N. Rosa ◽  
Massimo Ruzzene ◽  
Emil Prodan
Keyword(s):  
Magnetic Field ◽  
Quantum Hall Effect ◽  
Twist Angle ◽  
Quantum Hall ◽  
Topological Phases ◽  
Edge States ◽  
Layered Systems ◽  
Virtual Laboratories ◽  
Higher Dimensional ◽  
Chern Numbers

AbstractTwisted bilayered systems such as bilayered graphene exhibit remarkable properties such as superconductivity at magic angles and topological insulating phases. For generic twist angles, the bilayers are truly quasiperiodic, a fact that is often overlooked and that has consequences which are largely unexplored. Herein, we uncover that twisted n-layers host intrinsic higher dimensional topological phases, and that those characterized by second Chern numbers can be found in twisted bi-layers. We employ phononic lattices with interactions modulated by a second twisted lattice and reveal Hofstadter-like spectral butterflies in terms of the twist angle, which acts as a pseudo magnetic field. The phason provided by the sliding of the layers lives on 2n-tori and can be used to access and manipulate the edge states. Our work demonstrates how multi-layered systems are virtual laboratories for studying the physics of higher dimensional quantum Hall effect, and can be employed to engineer topological pumps via simple twisting and sliding.

scholarly journals The quantum Hall effect in the absence of disorder

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kyung-Su Kim ◽  
Steven A. Kivelson
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Quantum Hall Effect ◽  
Finite Interval ◽  
Quantum Hall ◽  
Wigner Crystal ◽  
Quasi Particle ◽  
Hall Conductance ◽  
Finite Extent

AbstractIt is widely held that disorder is essential to the existence of a finite interval of magnetic field in which the Hall conductance is quantized, i.e., for the existence of “plateaus” in the quantum Hall effect. Here, we show that the existence of a quasi-particle Wigner crystal (QPWC) results in the persistence of plateaus of finite extent even in the limit of vanishing disorder. Several experimentally detectable features that characterize the behavior in the zero disorder limit are also explored.

scholarly journals TRANSPORT PROPERTIES OF 2D ELECTRON GAS IN AN n-InGaAs/GaAs DQW IN A VICINITY OF LOW MAGNETIC-FIELD-INDUCED HALL INSULATOR–QUANTUM HALL LIQUID TRANSITION

2007 ◽  
Vol 06 (03n04) ◽  
pp. 173-177
Author(s):  
YU. G. ARAPOV ◽  
S. V. GUDINA ◽  
G. I. HARUS ◽  
V. N. NEVEROV ◽  
N. G. SHELUSHININA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Gas ◽  
Quantum Hall ◽  
Zero Magnetic Field ◽  
Double Quantum ◽  
Ballistic Regime ◽  
2D Electron Gas ◽  
Double Quantum Well ◽  
Liquid Transition ◽  
Low Magnetic Field

The resistivity (ρ) of low mobility dilute 2D electron gas in an n- InGaAs / GaAs double quantum well (DQW) exhibits the monotonic "insulating-like" temperature dependence (dρ/dT < 0) at T = 1.8–70 K in zero magnetic field. This temperature interval corresponds to a ballistic regime (kBTτ/ħ > 0.1–3.5) for our samples, and the electron density is on an "insulating" side of the so-called B = 0 2D metal–insulator transition. We show that the observed features of localization and Landau quantization in a vicinity of the low magnetic-field-induced insulator–quantum Hall liquid transition is due to the σxy(T) anomalous T-dependence.

scholarly journals Fractional Quantum Hall States at Zero Magnetic Field

2011 ◽  
Vol 106 (23) ◽  
Author(s):  
Titus Neupert ◽  
Luiz Santos ◽  
Claudio Chamon ◽  
Christopher Mudry
Keyword(s):  
Magnetic Field ◽  
Quantum Hall ◽  
Zero Magnetic Field ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Quantum Hall States ◽  
Hall States

Magnetic field induced charge redistribution in artificially disordered quantum Hall superlattices

2012 ◽  
Vol 97 (1) ◽  
pp. 17010 ◽  
Author(s):  
L. Fernandes dos Santos ◽  
Yu. A. Pusep ◽  
G. M. Gusev ◽  
A. K. Bakarov ◽  
A. I. Toropov
Keyword(s):  
Magnetic Field ◽  
Quantum Hall ◽  
Charge Redistribution ◽  
Induced Charge

INFLUENCE OF NEARBY QD LAYER ON 2DES IN QUANTUM HALL REGIME

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1445-1449
Author(s):  
K. TAKEHANA ◽  
Y. IMANAKA ◽  
T. TAKAMASU ◽  
M. HENINI
Keyword(s):  
Magnetic Field ◽  
Transport Properties ◽  
Gate Voltage ◽  
Quantum Hall ◽  
Electron System ◽  
Hall Resistance ◽  
Field Range ◽  
Voltage Range ◽  
Quantum Hall Regime ◽  
Hall Regime

We have investigated transport properties in high magnetic field of a gated two-dimensional electron system (2DES) separated by a thin barrier from a layer of self-assembled InAs quantum dots (QDs) in the quantum Hall regime. The quality of 2DES was found to be high enough to observe both integer and fractional quantum Hall effect (QHE), despite the proximity of the QD layer to the 2DES. However, significant suppression of the magnetoresistance (ρ xx ) and Hall resistance (ρ xy ) were observed in higher magnetic field range of filling factor ν < 1 when a positive voltage was applied to the front gate. The gate voltage dependence of ρ xx and ρ xy shows a well-defined hysteresis loop at the narrow gate voltage range between -0.2 and +0.2 V at ν < 1, while no anomaly was observed at ν > 1. We deduce that charging and discharging of QDs occurs when the gate voltage is varied around Vg ~ 0 V, which indicates that the electron charge states of the QDs affect the transport properties of the nearby 2DES only at ν < 1. We infer that the spin-flip process induces a non-equilibrium state in the 2DEG, which causes the suppression of ρ xx and ρ xy .

Realization of magnetic field reversible quantum Hall arrays

CPEM 2010 ◽  
2010 ◽  
Author(s):  
J. Konemann ◽  
J. Könemann ◽  
F. J. Ahlers ◽  
E. Pesel ◽  
K. Pierz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Hall

scholarly journals Quantum Hall Ferromagnetic-Paramagnetic Transition in p-Si/SiGe/Si Quantum Wells in a Tilted Magnetic Field

2012 ◽  
Vol 400 (4) ◽  
pp. 042005 ◽  
Author(s):  
I L Drichko ◽  
I Yu Smirnov ◽  
A V Suslov ◽  
O A Mironov ◽  
D R Leadley
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
Quantum Hall ◽  
Tilted Magnetic Field
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