scholarly journals The Nernst effect in Corbino geometry

2020 ◽  
Vol 117 (6) ◽  
pp. 2846-2851 ◽  
Author(s):  
A. V. Kavokin ◽  
B. L. Altshuler ◽  
S. G. Sharapov ◽  
P. S. Grigoryev ◽  
A. A. Varlamov
Keyword(s):  
Magnetic Field ◽  
Thermodynamic Potential ◽  
Infinite System ◽  
Chemical Potential ◽  
Dirac Fermions ◽  
Radial Temperature Gradient ◽  
Nernst Effect ◽  
Radial Temperature ◽  
The Magnetic Field ◽  
Corbino Disk

We study the manifestation of the Nernst effect in the Corbino disk subjected to the normal external magnetic field and to the radial temperature gradient. The Corbino geometry offers a precious opportunity for the direct measurement of the magnetization currents that are masked by kinetic contributions to the Nernst current in the conventional geometry. The magnetization currents, also referred to as the edge currents, are independent on the conductivity of the sample which is why they can be conveniently described within the thermodynamic approach. They can be related to the Landau thermodynamic potential for an infinite system. We demonstrate that the observable manifestation of this, purely thermodynamic, Nernst effect consists in the strong oscillations of the magnetic field measured in the center of the disk as a function of the external field. The oscillations depend on the temperature difference at the edges of the disk. Dirac fermions and 2D electrons with a parabolic spectrum are characterized by oscillations of different phase and frequency. We predict qualitatively different power dependencies of the magnitude of the Nernst signal on the chemical potential for normal and Dirac carriers.

Untersuchung des Druckaufbaus einer stationären, magnetfeldstabilisierten Helium-Entladung mit Hilfe magnetischer Messungen

1967 ◽  
Vol 22 (10) ◽  
pp. 1599-1612 ◽  
Author(s):  
Otto Klüber
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Plasma Column ◽  
Ambipolar Diffusion ◽  
Nernst Effect ◽  
Thermomagnetic Effect ◽  
Field Coil ◽  
Neutral Gas ◽  
Ring Currents ◽  
The Magnetic Field

A stationary discharge is produced bya current flowing parallel to the magnetic field ofa cylindrical coil. In the region where the field is homogeneous the pressure in the plasma column is much higher than that in the surrounding neutral gas. This is mainly caused by diamagnetic ring currents, as is shown by measuring the magnetic flux due to these currents. Two effects are primarily responsible for the ring currents in this region: The already known effect of the ambipolar diffusion across the magnetic field anda thermomagnetic effect, called NERNST effect, whose influence on the pressure build-up ofa plasma has not been investigated hitherto. Other phenomena causing ring currents occur in the plasma near the coil ends and outside the field coil.

scholarly journals Equation of State of a Magnetized Dense Neutron System

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 104 ◽  
Author(s):  
Efrain J. Ferrer ◽  
Aric Hackebill
Keyword(s):  
Magnetic Field ◽  
Equation Of State ◽  
Chemical Potential ◽  
Compact Objects ◽  
Field Direction ◽  
Neutron Density ◽  
Magnetic Field Direction ◽  
System Equation ◽  
The One ◽  
The Magnetic Field

We discuss how a magnetic field can affect the equation of state of a many-particle neutron system. We show that, due to the anisotropy in the pressures, the pressure transverse to the magnetic field direction increases with the magnetic field, while the one along the field direction decreases. We also show that in this medium there exists a significant negative field-dependent contribution associated with the vacuum pressure. This negative pressure demands a neutron density sufficiently high (corresponding to a baryonic chemical potential of μ = 2.25 GeV) to produce the necessary positive matter pressure that can compensate for the gravitational pull. The decrease of the parallel pressure with the field limits the maximum magnetic field to a value of the order of 10 18 G, where the pressure decays to zero. We show that the combination of all these effects produces an insignificant variation of the system equation of state. We also found that this neutron system exhibits paramagnetic behavior expressed by the Curie’s law in the high-temperature regime. The reported results may be of interest for the astrophysics of compact objects such as magnetars, which are endowed with substantial magnetic fields.

NUMERICAL INVESTIGATION OF SILICON MELT FLOW IN A SHALLOW ANNULAR POOL UNDER AN AXIAL MAGNETIC FIELD

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3486-3488
Author(s):  
YOU-RONG LI ◽  
DONG-MING MO ◽  
LAN PENG ◽  
SHUANG-YING WU
Keyword(s):  
Magnetic Field ◽  
Steady Flow ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Melt Flow ◽  
Radial Temperature ◽  
Annular Pool ◽  
Silicon Melt ◽  
Surface Patterns ◽  
The Magnetic Field

In order to understand the effect of the magnetic field on surface patterns on semi-conducting silicon melt in industrial Czochralski furnaces, we conducted a series of unsteady three-dimensional numerical simulations of silicon melt flow in a shallow annular pool under the axial magnetic field for the magnetic field strength from 0 to 0.1T. The pool is heated from the outer cylindrical wall and cooled at the inner wall. Bottom and top surfaces are adiabatic. When the magnetic field is weak, the simulation can predict various three-dimensional oscillatory flows depending on the radial temperature difference. With the much larger magnetic field, three-dimensional flow becomes axisymmetric steady flow. Details of flow and temperature disturbances are discussed and the critical magnetic field strengths for the onset of axisymmetric steady flow are determined.

scholarly journals Critical end point in a thermomagnetic nonlocal NJL model

2017 ◽  
Vol 32 (26) ◽  
pp. 1750162 ◽  
Author(s):  
F. Márquez ◽  
R. Zamora
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Chemical Potential ◽  
First Order ◽  
End Point ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
The Magnetic Field

In this paper, we explore the critical end point in the [Formula: see text] phase diagram of a thermomagnetic nonlocal Nambu–Jona-Lasinio model in the weak field limit. We work with the Gaussian regulator, and find that a crossover takes place at [Formula: see text], [Formula: see text]. The crossover turns to a first-order phase transition as the chemical potential or the magnetic field increases. The critical end point of the phase diagram occurs at a higher temperature and lower chemical potential as the magnetic field increases. This result is in accordance to similar findings in other effective models. We also find that there is a critical magnetic field, for which a first-order phase transition takes place even at [Formula: see text].

scholarly journals Harmonically trapped one-dimensional Fermi gas using the static fluctuation approximation

2016 ◽  
Vol 94 (1) ◽  
pp. 47-57 ◽  
Author(s):  
H.A. Al-Khzon ◽  
H.B. Ghassib ◽  
Mohamed K. Al-Sugheir
Keyword(s):  
Magnetic Field ◽  
Heat Capacity ◽  
Chemical Potential ◽  
Attractive Potential ◽  
Large N ◽  
Static Fluctuation Approximation ◽  
Trapped Fermions ◽  
Static Fluctuation ◽  
The Magnetic Field ◽  
Number Of Particles

A system of a finite number of harmonically trapped fermions in one dimension, in the presence of a static magnetic field, is studied within the framework of the static fluctuation approximation, for different repulsive and attractive potential strengths. Specifically, the thermodynamic properties of the system (the chemical potential, total energy, heat capacity, and entropy), as well as its magnetic properties (the magnetization and susceptibility), are calculated. It is observed that the system remains in an ordered phase for a small number of particles N, even at high temperatures T. Disorder sets in for large N, even at low T. The effect of the potential strength on the heat capacity is particularly tangible in the region bordering the quantum and classical regimes. The effect of the temperature (representing disorder) is directly opposite to that of the magnetic field (representing order), as expected on basic physical grounds. These features are consistent with experimental results.

scholarly journals Incoherent hydrodynamics of density waves in magnetic fields

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Aristomenis Donos ◽  
Christiana Pantelidou ◽  
Vaios Ziogas
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Density Wave ◽  
Density Waves ◽  
Hydrodynamic Modes ◽  
Momentum Relaxation ◽  
Effective Theories ◽  
The Magnetic Field

Abstract We use holography to derive effective theories of fluctuations in spontaneously broken phases of systems with finite temperature, chemical potential, magnetic field and momentum relaxation in which the order parameters break translations. We analytically construct the hydrodynamic modes corresponding to the coupled thermoelectric and density wave fluctuations and all of them turn out to be purely diffusive for our system. Upon introducing pinning for the density waves, some of these modes acquire not only a gap, but also a finite resonance due to the magnetic field. Finally, we study the optical properties and perform numerical checks of our analytical results. A crucial byproduct of our analysis is the identification of the correct current which describes the transport of heat in our system.

Die Energiebilanz eines Wasserstoffbogens in axialem Magnetfeld

1965 ◽  
Vol 20 (3) ◽  
pp. 475-484 ◽  
Author(s):  
Udo Heidrich
Keyword(s):  
Magnetic Field ◽  
Electrical Power ◽  
Homogeneous Magnetic Field ◽  
Hydrogen Atmosphere ◽  
Arc Length ◽  
Radial Temperature ◽  
Cylindrically Symmetric ◽  
Radiation Losses ◽  
Current Voltage ◽  
The Magnetic Field

The numerical solution of the energy balance of a cylindrically symmetric hydrogen arc immersed in an axial, strong, homogeneous magnetic field led to the current-voltage-characteristic and the radial temperature distribution. Three types of arc models were used, each with different assumptions on radiation losses. The results show that, by the reduction of the thermal conductivity perpendicular to the magnetic field for a fully ionized plasma, the necessary electrical power is diminished for temperatures along the axis higher than about 2·104°K. For example, an arc with 1 cm radius in a hydrogen atmosphere of 5 · 104 dyne/cm2, in an external magnetic field of 20 kGauss, a temperature along the axis of 105°K requires about 3,5 kW per cm arc length. Of this, radiation losses account for about 0,5 kW per cm. However, without a superimposed magnetic field the electrical power is about 200 kW per cm.

scholarly journals Universal upper bound for the entropy of superconducting vortices and the quantum Nernst effect

2021 ◽  
Author(s):  
Cristina Diamantini ◽  
Carlo Trugenberger ◽  
Valerii Vinokur
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Upper Bound ◽  
Nernst Effect ◽  
Quantum Vortex ◽  
Superconducting Vortices ◽  
Integer Quantum ◽  
The Magnetic Field

Abstract We show that the entropy per quantum vortex per layer in superconductors in external magnetic fields is bounded by the universal value kBln 2, which explains puzzling results of recent experiments on the Nernst effect. The observed plateau of the Nernst signal as a function of the magnetic field is correspondingly attributed to a manifestation of the integer quantum Nernst effect.

scholarly journals Investigation of Magneto-phonon Resonance in Graphene Monolayers

2017 ◽  
Vol 33 (4) ◽  
Author(s):  
Bui Dinh Hoi
Keyword(s):  
Magnetic Field ◽  
Linear Response ◽  
Resonant Scattering ◽  
Linear Response Theory ◽  
Landau Levels ◽  
Effect Of Temperature ◽  
Perpendicular Magnetic Field ◽  
Dirac Fermions ◽  
Deformation Potential ◽  
The Magnetic Field

In this work, utilising the linear response theory we calculate the magneto conductivity (MC) in graphene monolayers, subjected to a static perpendicular magnetic field. The interaction of Dirac fermions with optical phonon via deformation potential is taken into account at high temperature. The dependence of the MC on the magnetic field shows resonant peaks that describe transitions of electrons between Landau levels via the resonant scattering with optical phonons. The effect of temperature on the MC is also obtained and discussed.

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