Search query: Quantizing magnetic field

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abstract: Applying a strong magnetic field to a Dirac or Weyl semimetal can produce record large thermopower and figure of merit. The thermoelectric effect is the generation of an electrical voltage from a temperature gradient in a solid material due to the diffusion of free charge carriers from hot to cold. Identifying materials with a large thermoelectric response is crucial for the development of novel electric generators and coolers. We theoretically consider the thermopower of Dirac/Weyl semimetals subjected to a quantizing magnetic field. We contrast their thermoelectric properties with those of traditional heavily doped semiconductors and show that, under a sufficiently large magnetic field, the thermopower of Dirac/Weyl semimetals grows linearly with the field without saturation and can reach extremely high values. Our results suggest an immediate pathway for achieving record high thermopower and thermoelectric figure of merit, and they compare well with a recent experiment on Pb1 xSnxSe.
author_names: Brian Skinner

Liang Fu
title: Large, nonsaturating thermopower in a quantizing magnetic field
venue: Science Advances
year: 2018

abstract: A theoretical investigation is presented for ion acoustic Gardner solitons (GSs) and double layers (DLs) in a multi ion plasma system. The plasma consists of inertial positively and negatively charged ions and negatively charged immobile heavy ions and electrons which are in trapping distribution, all existing in a quantizing magnetic field. The reductive perturbation method is used to derive Korteweg de Vries (KdV) modified KdV (mKdV) and Gardner equations. It is found that the KdV solitons and Gardner solitons (GSs) are either compressive or rarefactive depending on the plasma parameters, whereas only compressive solitons are obtained in the mKdV case, wherever Gardner positive DLs exist. These solitons are significantly modified due to the introduction of the trapping parameter and polarization coefficient. The presented results are considered to be beneficial in understanding the solitary structures in dense quantum plasmas such as those existing in white dwarfs.
author_names: W F El-Taibany

A Atteya

S K El-Labany
title: Ion acoustic Gardner solitons in multi ion degenerate plasma with the effect of polarization and trapping in the presence of a quantizing magnetic field
year: 2018

abstract: In the present work, we have investigated the effect of trapping as a microscopic phenomenon on the formation of solitary structures in the presence of a quantizing magnetic field in an electron positron ion (e p i) plasma having degenerate electrons and positrons, whereas ions are taken to be classical and cold. We have found that positron concentration, quantizing magnetic field, and finite electron temperature effects not only affect the linear dispersion characteristics of the electrostatic waves under consideration but also have a significant bearing on the propagation of solitary structures in the nonlinear regime. Importantly, the system under consideration has been found to allow the formation of compressive solitary structures only. The work presented here may be beneficial to understand the propagation of nonlinear electrostatic structures in dense astrophysical environments and in intense laser plasma interactions.
author_names: Muhammad M Iqbal

Waqas Masood

H A Shah

Nodar L Tsintsadze
title: Nonlinear density excitations in electron positron ion plasmas with trapping in a quantizing magnetic field
year: 2017

abstract: We study charge and spin transport along grain boundaries in single layer graphene in the presence of a quantizing magnetic field. Transport states in a grain boundary are produced by hybridization of Landau zero modes with interfacial states. In selected energy regimes quantum Hall edge states can be deflected either fully or partially into grain boundary states. The degree of edge state deflection is studied in the nonlocal conductance and in the shot noise. We also consider the possibility of grain boundaries as gate switchable spin filters, a functionality enabled by counterpropagating transport channels laterally confined in the grain boundary.
author_names: Madeleine Phillips

Eugene J Mele
title: Charge and spin transport on graphene grain boundaries in a quantizing magnetic field
year: 2017

abstract: Transport experiments on the two dimensional electron gas (2DEG) confined into a semiconductor quantum well and subjected to a quantizing magnetic field have uncovered a rich variety of uniform and nonuniform phases such as the Laughlin liquids, the Wigner, bubble and Skyrme crystals and the quantum Hall stripe state. Optically pumped nuclear magnetic resonance (OP NMR) has also been extremely useful in studying the magnetization and dynamics of electron solids with exotic spin textures such as the Skyrme crystal. Recently, it has been demonstrated that a related technique, resistively detected nuclear magnetic resonance (RD NMR) could be a good tool to study the topography of the electron solids in the fractional and integer quantum Hall regimes. In this work, we compute theoretically the RD NMR line shapes of various crystal phases of the 2DEG and study the relation between their spin density and texture and their NMR spectra. This allows us to evaluate the ability of the RD NMR to discriminate between the various types of crystal states.
author_names: Ren'e Cot'e

Alexandre Simoneau
title: Resistively detected NMR spectra of the crystal states of the two dimensional electron gas in a quantizing magnetic field
year: 2016

abstract: For nonparabolic dispersion law determined by the density of the energy states in a quantizing magnetic field, the dependence of the density of energy states on temperature in quantizing magnetic fields is studied with the nonquadratic dispersion law. Experimental results obtained for PbTe were analyzed using the suggested model. The continuous spectrum of the energy density of states at low temperature is transformed into discrete Landau levels.
author_names: G Gulyamov

U I Erkaboev

P J Baymatov
title: Determination of the Density of Energy States in a Quantizing Magnetic Field for Model Kane
year: 2016

abstract: In a graphene \em pn} junction at high magnetic field, unidirectional "snake states" are formed at the \em pn} interface. In a clean \em pn} junction, each snake state exists in one of the valleys of the graphene band structure, and the conductance of the junction as a whole is determined by microscopic details of the coupling between the snake states at the \em pn} interface and quantum Hall edge states at the sample boundaries [Tworzydlo \em et al. Phys. Rev. B \bf 76} 035411 (2007) Disorder mixes and couples the snake states. We here report a calculation of the full conductance distribution in the crossover between the clean limit and the strong disorder limit, in which the conductance distribution is given by random matrix theory [Abanin and Levitov, Science \bf 317} 641 (2007) Our calculation involves an exact solution of the relevant scaling equation for the scattering matrix, and the results are formulated in terms of parameters describing the microscopic disorder potential in bulk graphene.
author_names: Christian Fraessdorf

Luka Trifunovic

Nils Bogdanoff

Piet W Brouwer
title: Graphene pn junction in a quantizing magnetic field
year: 2016

abstract: In the present investigation, linear and nonlinear propagation of low frequency oOci) electrostatic waves have been studied in a spatially inhomogeneous degenerate plasma with one dimensional electron trapping in the presence of a quantizing magnetic field and finite temperature effects. Using the drift approximation, formation of 1 and 2D drift ion solitary structures have been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs for illustrative purpose. It is observed that the inclusion of Landau quantization significantly changes the expression of the electron number density of a dense degenerate plasma which affects the linear and nonlinear propagation of drift acoustic solitary waves in such a system. The present work may be beneficial to understand the propagation of drift solitary structures with weak transverse perturbation in a variety of physical situations, such as white dw.
author_names: Waqas Masood

Muzzamal I Shaukat

H A Shah

Arshad M Mirza
title: Solitary structures in a spatially nonuniform degenerate plasma in the presence of quantizing magnetic field
year: 2015

abstract: The effect of adiabatic trapping as a microscopic phenomenon in an inhomogeneous degenerate plasma is investigated in the presence of a quantizing magnetic field, and a modified Hasegawa Mima equation for the drift ion acoustic wave is obtained. The linear dispersion relation in the presence of the quantizing magnetic field is investigated. The modified Hasegawa Mima equation is investigated to obtain bounce frequencies of the trapped particles. The Korteweg de Vries equation is derived for the two dimensional case and finally the Sagdeev potential approach is used to obtain solitary structures. The theoretically obtained results have been analyzed numerically for different astrophysical plasma and quantizing magnetic field values.
author_names: Sabeen Arshad

H A Shah

M N S Qureshi
title: Effect of adiabatic trapping on vortices and solitons in degenerate plasma in the presence of a quantizing magnetic field
year: 2014

abstract: The dependence of the density of energy states (Ns) on temperature in quantizing magnetic fields is studied. It is shown that, as temperature is increased, the Landau levels are blurred as a result of thermal widening and the quantities Ns are transformed into the density of states as in the absence of a magnetic field. The temperature dependence of the distribution of the density of energy states in high magnetic fields for semiconductors is considered using a mathematical model. It is shown that the continuous spectrum of density of states measured at liquid nitrogen temperature is transformed into discrete Landau levels at lower temperatures. Mathematical simulation of the processes with the use of experimental data for the continuous spectrum of the density of states makes it possible to calculate the discrete Landau levels. Experimental results obtained for PbS are analyzed using the suggested model. The density of states at low temperatures is calculated from data on high temperature Ns.
author_names: G Gulyamov

U I Erkaboev

N Yu Sharibaev
title: Effect of temperature on the thermodynamic density of states in a quantizing magnetic field
year: 2014