Unified Semi-Classical Theory of Parallel and Perpendicular Giant Magnetoresistance in Superlattices

1995 ◽  
Vol 384 ◽  
Author(s):  
V.V. Ustinov ◽  
E.A. Kravtsov
Keyword(s):  
Boundary Conditions ◽  
Classical Theory ◽  
Giant Magnetoresistance ◽  
Distribution Functions ◽  
Classical Approach ◽  
Conduction Electrons ◽  
Boltzman Equation ◽  
Magnetic Superlattices ◽  
Exact Boundary ◽  
Spin Dependent Scattering

ABSTRACTThe giant magnetoresistance in magnetic superlattices for the current perpendicular to and in the layer planes is studied within a unified semi-classical approach that is based on the Boltzman equation with exact boundary conditions for the spin-dependent distribution functions of conduction electrons. We show that the main differences between the in-plane and perpendicular-to-plane magnetoresistance result from the fact that they originate from different interface processes responsible for spin-dependent scattering. A correlation between the giant magnetoresistance and the superlattice magnetization is also discussed and it is shown that its study has much potential for yielding information about properties of spin-dependent scattering in magnetic superlattices.

A QUANTUM MODEL FOR THE GIANT MAGNETORESISTANCE EFFECT

1996 ◽  
Vol 10 (17) ◽  
pp. 2103-2110
Author(s):  
LEI ZHOU ◽  
RUIBAO TAO
Keyword(s):  
Simple Model ◽  
Electric Conductivity ◽  
Giant Magnetoresistance ◽  
Quantum Model ◽  
Magnetoresistance Effect ◽  
Conduction Electrons ◽  
Giant Magnetoresistance Effect ◽  
Model Hamiltonian ◽  
Spin Dependent Scattering ◽  
Scattering Potential

A quantum explanation based on the previous semi-classical theory has been presented for the giant magnetoresistance (GMR) effect in this letter. A simple model Hamiltonian has been proposed for the conduction electrons in the magnetic layered structures in which the interaction of the conduction electrons with the local spins and the spin-dependent scattering potential have been considered, then an analytical expression of the effective electric conductivity is derived after some simplifying procedures. The main feature of the GMR effect may be explained by this simple model qualitatively.

An iterative approach for analysis of cracks with exact boundary conditions in finite magnetoelectroelastic solids

2019 ◽  
Vol 28 (5) ◽  
pp. 055025 ◽  
Author(s):  
MingHao Zhao ◽  
QiaoYun Zhang ◽  
XinFei Li ◽  
YaGuang Guo ◽  
CuiYing Fan ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Iterative Approach ◽  
Exact Boundary ◽  
Magnetoelectroelastic Solids

Moving axial load on dynamic response of single-walled carbon nanotubes using classical, Rayleigh and Bishop rod models based on Eringen’s theory

2019 ◽  
Vol 26 (11-12) ◽  
pp. 913-928 ◽  
Author(s):  
Seyed Amirhosein Hosseini ◽  
Farshad Khosravi ◽  
Majid Ghadiri
Keyword(s):  
Carbon Nanotubes ◽  
Boundary Conditions ◽  
Classical Theory ◽  
Moving Load ◽  
Nonlocal Parameter ◽  
Excitation Frequency ◽  
Single Walled Carbon Nanotubes ◽  
Axial Displacement ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

The main objective of the present work is devoted to the study of both free and time-dependent forced axial vibration simultaneously in single-walled carbon nanotubes subjected to a moving load. The governing equation is derived via Hamilton’s principle. Classical theory, along with the Rayleigh and Bishop theories, is used to analyze the nonlocal vibrational behaviors of single-walled carbon nanotubes. A Galerkin method is established to solve the derived equations. The boundary conditions are assumed to be clamped-clamped and clamped-free. Firstly, the variation of nondimensional natural frequencies is calculated based on the classical theory, and the effect of the nonlocal parameter, the mode number and the length is illustrated and schematically compared for clamped-clamped and clamped-free boundary conditions. Besides, the obtained nondimensional responses are compared with the results of another study to validate the accuracy of the used method. Ultimately, the dynamic axial displacement due to the moving load in the time domain has been studied for the first time. Furthermore, the effects of the thickness, length, velocity of the moving load, excitation frequency, and the nonlocal parameter based on the classical, Rayleigh, and Bishop theories are investigated in this paper. Also, the influence of the nonlocal parameter on the variations of maximum axial displacement with respect to the velocity parameter for the aforementioned boundary conditions and theories is evaluated relative to each other.

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