Anisotropic Magnetoresistance of Stretched Sheets of Carbon Nanotubes

2012 ◽  
Vol 1407 ◽  
Author(s):  
Elena Cimpoiasu ◽  
David Lashmore ◽  
Brian White ◽  
George A. Levin
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Nitric Acid ◽  
Electric Current ◽  
Anisotropic Magnetoresistance ◽  
Catalyst Nanoparticles ◽  
Positive Term ◽  
The Magnetic Field ◽  
Bulk Carbon

ABSTRACTWe performed magnetoresistance (MR) measurements on bulk carbon nanotube sheets that had been partially aligned by post-fabrication stretching. The magnetic field was applied under different orientations with respect to the direction of the stretch, while the electric current was either parallel or perpendicular to the direction of the stretch. We found that the fielddependence of the MR is composed of two terms, one positive and one negative. The magnitudes of both terms are largest when the field is parallel with the direction of the stretch. If the sheets are treated with nitric acid, the positive term is removed and the MR is smallest when the field is aligned with the magnetic field. We attribute these anisotropic features to magnetoelastic effects induced by the coupling between the magnetic catalyst nanoparticles, the magnetic field, and the network of nanotubes.

Giant actuation in bulk carbon nanotubes under coupled electric and magnetic fields

RSC Advances ◽  
2015 ◽  
Vol 5 (33) ◽  
pp. 26157-26162 ◽  
Author(s):  
Prarthana Gowda ◽  
Soumalya Mukherjee ◽  
Siva K. Reddy ◽  
Rituparna Ghosh ◽  
Abha Misra
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Electro Magnetic Field ◽  
Electric And Magnetic Fields ◽  
Coupled Field ◽  
Electro Magnetic ◽  
The Individual ◽  
Piezoelectric Behavior ◽  
Bulk Carbon

The transformation of electrostrictive to piezoelectric behavior is observed in carbon nanotube under coupled electro-magnetic field. Five times higher actuation response was observed under coupled field as compared to the individual fields.

Topology Optimized Vibration Control of a Fluid–Conveying Carbon Nanotube with Non-Uniform Magnetic Field

2015 ◽  
Vol 07 (06) ◽  
pp. 1550092 ◽  
Author(s):  
Zijun Zhang ◽  
Yongshou Liu ◽  
Hailong Zhao ◽  
Wei Liu
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Uniform Magnetic Field ◽  
Scale Effects ◽  
Small Scale ◽  
Simply Supported ◽  
Eigen Frequencies ◽  
Critical Velocities ◽  
The Magnetic Field

This paper presents an approach to control the fluid-induced vibration of the carbon nanotubes (CNTs) embedded in viscoelastic medium with topology non-uniform magnetic field. Non-local continuum theory and homogenization equivalence are employed to conclude small-scale effects of the carbon nanotube (CNT) and the nanofluid, respectively. Simply supported, fixed–fixed and fixed–pinned fluid–conveying carbon nanotubes (FCCNTs) with sliding and no-sliding ends are chosen as samples to illustrate the control effect of the magnetic field, and the optimal magnetic field distributions are obtained through genetic algorithm (GA). Dynamic characteristics (the eigen-frequencies and the critical velocities) of different FCCNT models are calculated through differential quadrature (DQ) method. The control effects of the magnetic field can be validated through examining the stiffness enhancement of the Ampere’s force. Results present that the eigen-frequencies and critical velocities of different FCCNTs are all raised by 3–13% through the given magnetic fields. Contrasts between different models illustrate that the dynamic stiffness of simply supported FCCNT with no-sliding ends is enhanced mostly by the magnetic field.

scholarly journals The effect of simplifications of a numerical mesh on the results of electromagnetic analysis of the Nuclotron-type cable

2018 ◽  
Vol 177 ◽  
pp. 08004
Author(s):  
Łukasz Tomków
Keyword(s):  
Magnetic Field ◽  
Electric Current ◽  
Current Density ◽  
Electric Current Density ◽  
Electromagnetic Analysis ◽  
First Case ◽  
Single Region ◽  
The Magnetic Field

The model of a single Nuclotron-type cable is presented. The goal of this model is to assess the behaviour of the cable under different loads. Two meshes with different simplifications are applied. In the first case, the superconductor in the cable is modelled as single region. Second mesh considers individual strands of the cable. The significant differences between the distributions of the electric current density obtained with both models are observed. The magnetic field remains roughly similar.

scholarly journals The hall effect in liquid electrolytes

1913 ◽  
Vol 88 (606) ◽  
pp. 588-604 ◽  
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Electric Current ◽  
Metal Plate ◽  
Satisfactory Explanation ◽  
Thermo Electric ◽  
Field Independent ◽  
Set Up ◽  
The Magnetic Field ◽  
Thin Metal Plate

The distortion of the lines of flow of an electric current in a thin metal plate by the action of a magnetic field was discovered in 1879. Hall attributed this to the action of the magnetic field on the molecular currents in the metal film, which were deflected to one side or the other and accompanied by a corresponding twist of the equipotential lines. This explanation did not pass without criticism, and another theory of the effect found by Hall was published in 1884. In that paper the author seeks to explain the effect by assuming a combination of certain mechanical strains and Peltier effects, a thermo-electric current being set up between the strained and the unstrained portions. The effect of such strain was to produce a reverse effect in some metals, and these were precisely the metals for which the Hall effect was found to reverse. Aluminium was the only exception. In other respects, however, as shown by Hall in a later paper, Bidwell's theory did not stand the test of experiment, and the results lend no support to his theory, while they are in complete accordance withe the explanation that the molecular currents are disturbed by the action of the magnetic field. On the electron theory of metallic conduction, the mechanism of the Hall effect is more obvious, but at present no satisfactory explanation of the reversal found in some metals is known. Further experiments have made it clear that there is a real deflection of the elementary currents, due to the application of the magnetic field, independent of any effect due to strain.

The impact of the Marangoni convection and magnetic field versus blood-based carbon nanotube nanofluids

2019 ◽  
Vol 234 (1-2) ◽  
pp. 37-46
Author(s):  
Taza Gul ◽  
Ramla Akbar ◽  
Zafar Zaheer ◽  
Iraj S Amiri
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Marangoni Convection ◽  
Thin Liquid Film ◽  
Casson Fluid ◽  
Single Walled Carbon Nanotube ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes ◽  
The Impact

The mutual result of the magnetic field and Marangoni convection against the thin liquid film of Casson fluid, blood-based carbon nanotube nanofluid has been fruitfully discussed in this article. The influence of various model constraints is focused on velocity, heat transfer, pressure distribution, skin friction and Nusselt number through graphical illustration. In addition, we witness that the thermal field of liquid raises with the growing value of [Formula: see text] and this upsurge is more in single-walled carbon nanotubes and is more dominant than multi-walled carbon nanotubes. The controlling approach of the homotopy analysis method has been used for velocity and temperature distribution. For authentication, the achieved results have been associated with the numerical (ND-Solve) method and displayed. This investigation shows that the velocity profile in the case of Casson fluid single-walled carbon nanotube–blood nanofluid is comparatively less affected and the temperature field of single-walled carbon nanotube–blood nanofluid dominates multi-walled carbon nanotube–blood nanofluid.

The equilibrium configuration of a slowly rotating mass of liquid in the presence of a poloidal magnetic field

1972 ◽  
Vol 55 (1) ◽  
pp. 105-112
Author(s):  
C. Sozou
Keyword(s):  
Magnetic Field ◽  
Electric Current ◽  
Equilibrium Configuration ◽  
Spherical Surface ◽  
Perturbation Expansion ◽  
Reverse Direction ◽  
Poloidal Magnetic Field ◽  
Inviscid Liquid ◽  
Axis Of Rotation ◽  
The Magnetic Field

The equilibrium configuration of a slowly rotating self-gravitating perfectly conducting inviscid liquid, in the presence of a small poloidal magnetic field, is considered for a case where the electric current is a simple function of the distance from the axis of rotation. Owing to the coupling of the magnetic field with the rotation the electric current may reverse direction. This could make the magnetic field zero on certain surfaces and impose restrictions on the parameters of the problem. A perturbation expansion of the nearly spherical surface of the liquid is constructed.

scholarly journals Magnetic Field Generated during Electric Current-Assisted Sintering: From Health and Safety Issues to Lorentz Force Effects

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1653
Author(s):  
Huaijiu Deng ◽  
Jian Dong ◽  
Filippo Boi ◽  
Theo Saunders ◽  
Chunfeng Hu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Current ◽  
Lorentz Force ◽  
Health And Safety ◽  
Interparticle Contact ◽  
Safety Issues ◽  
Contact Points ◽  
The Magnetic Field ◽  
Health And Safety Issues

In the past decade, a renewed interest on electromagnetic processing of materials has motivated several investigations on the interaction between matter, electric and magnetic fields. These effects are primarily reconducted to the Joule heating and very little attention has been dedicated to the magnetic field contributions. The magnetic field generated during electric current-assisted sintering has not been widely investigated. Magnetism could have significant effects on sintering as it generates significant magnetic forces, resulting in inductive electrical loads and preferential heating induced by overlapping magnetic fields (i.e., proximity effect). This work summarizes the magnetic field effects in electric current-assisted processing; it focuses on health and safety issues associated with large currents (up to 0.4 MA); using FEM simulations, it computes the self-generated magnetic field during spark plasma sintering (SPS) to consolidate materials with variable magnetic permeability; and it quantifies the Lorentz force acting at interparticle contact points. The results encourage one to pay more attention to magnetic field-related effects in order to engineer and exploit their potentials.

MAGNETORESISTANCE IN COPPER

2008 ◽  
Vol 22 (25n26) ◽  
pp. 4434-4441
Author(s):  
SHIGEJI FUJITA ◽  
NEBI DEMEZ ◽  
JEONG-HYUK KIM ◽  
H. C. HO
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Kinetic Theory ◽  
Anisotropic Magnetoresistance ◽  
Magnetic Field Direction ◽  
Conduction Electrons ◽  
Fcc Lattice ◽  
A Charge ◽  
The Magnetic Field ◽  
Cyclotron Mass

The motion of the guiding center of magnetic circulation generates a charge transport. By applying kinetic theory to the guiding center motion, an expression for the magnetoconductivity σ is obtained: σ = e2ncτ/M*, where M* is the magnetotransport mass distinct from the cyclotron mass, nc the density of the conduction electrons, and τ the relaxation time. The density nc depends on the magnetic field direction relative to copper's fcc lattice, when Cu's Fermi surface is nonspherical with “necks”. The anisotropic magnetoresistance is analyzed based on a one-parameter model, and compared with experiments. A good fit is obtained.

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