EFFECTIVE BAND MODEL OF GIANT MAGNETORESISTANCE

We consider the transport properties in magnetic multilayers for electronic current in the plane of the surfaces. The model is based on the effective s-band construction for the multilayer consisting of the metallic spacer and two ferromagnetic layers characterized by s–d coupling. We discuss the quasielectron spectrum in its effective mass approximation, with the perturbation taken into account by the effective potential, which also includes the interface contributions. We find the energy dispersion and the Fermi level for the effective s-band common for electrons in the whole sample. The results are equivalent in fact to those obtained within the Hoon–Falicov model, but they seem to us much simpler and more transparent for their extensions and applications.

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Microstructure of spin-valve mr sandwiches

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138798 ◽

1995 ◽

Vol 53 ◽

pp. 484-485

Author(s):

L. Tang ◽

M. Xiao ◽

D.E. Laughlin ◽

M. H. Kryder

Keyword(s):

Giant Magnetoresistance ◽

Metal Layer ◽

Spin Valve ◽

High Sensitivity ◽

Magnetic Multilayers ◽

Multilayered Structures ◽

Ferromagnetic Layers ◽

Antiferromagnetic Layer ◽

Intensive Investigation ◽

High Density Magnetic Recording

Giant magnetoresistance ( GMR ) effects in magnetic multilayers with spin-valve structures are under intensive investigation. The GMR effects in spin-valve structures originate from the change in the orientation of magnetization in the successive ferromagnetic layers. Of the various types of spin-valve multilayered structures reported, spin-valve sandwiches, in which one of the two ferromagnetic layers separated by a nonferromagnetic metal layer is constrained through exchange coupling to an adjacent antiferromagnetic layer, are most promising for applications in read heads for high density magnetic recording. This is due to their large MR and high sensitivity in low magnetic fields. Study of the correlation between magnetic/magnetotransport properties and the microstructure of spin-valve sandwiches is crucial for a better understanding of the mechanism of the spin-valve effects and for future MR heads design. Here, we present the results of transmission electron microscopy (TEM) studies of the microstructure of a Ni81Fe19(47Å)\Cu(18Å)\Ni81Fe19(53Å)\FeMn(186Å) spin-valve sandwich.

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CORRELATION BETWEEN THE POTENTIAL CONTRIBUTION AND MAGNETIC TRANSPORT PROPERTIES FOR MAGNETIC MULTILAYERS

International Journal of Modern Physics B ◽

10.1142/s0217979299001508 ◽

1999 ◽

Vol 13 (11) ◽

pp. 1437-1446

Author(s):

LING-YUN ZHANG ◽

HONG SUN ◽

BO-ZANG LI ◽

FU-CHO PU

Keyword(s):

Transport Properties ◽

Giant Magnetoresistance ◽

Impurity Scattering ◽

Potential Effect ◽

Magnetic Multilayers ◽

Exchange Potential ◽

Potential Contribution ◽

Magnetic Multilayer ◽

Scattering Potential ◽

Magnetic Transport

We discuss the exchange potential and impurity scattering potential effect on the magnetic transport properties of magnetic multilayers. In the case of Hartree–Fork approximation, the model Hamiltonian with respect to the magnetization and potential contribution is presented. The expression of giant magnetoresistance is obtained by considering both interface and bulk magnetization contribution. The results show that the giant magnetoresistance in magnetic multilayer is different for different layer thickness. Meanwhile, we also clarify the interface and bulk contribution of the giant magnetoresistance in magnetic multilayer for different exchange potential and impurity scattering potential.

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SEMPA Studies of Exchange Coupling in Magnetic Multilayers

MRS Bulletin ◽

10.1557/s0883769400045310 ◽

1995 ◽

Vol 20 (10) ◽

pp. 30-33 ◽

Cited By ~ 6

Author(s):

R.J. Celotta ◽

D.T. Pierce ◽

J. Unguris

Keyword(s):

Magnetic Field ◽

Exchange Coupling ◽

Giant Magnetoresistance ◽

Large Change ◽

Magnetic Multilayers ◽

Information Storage ◽

Conduction Electrons ◽

Spacer Layer ◽

Ferromagnetic Layers ◽

Oscillatory Coupling

In the late 1980s, a number of exciting yet puzzling observations resulted from experiments investigating the coupling between two ferromagnetic layers separated by a nonferromagnetic spacer layer. A pioneering experiment by Grünberg et al. showed that Fe layers separated by a thin Cr spacer aligned with antiparallel magnetization, but with Au as the spacer layer, a parallel alignment occurred. The long-range magnetic dipole from each layer would tend to explain antiparallel alignment; small pinholes in the spacer layer would produce parallel alignment. Alternatively, the layers might be coupled through the spacer-layer conduction electrons by the Ruder man-Kittel-Kasuya-Yosida (RKKY) effect. This was expected to produce an oscillation in coupling as the spacer thickness increased, that is, an oscillation between parallel and antiparallel alignment. Oscillatory coupling was first observed by Parkin et al. Researchers had also found that, at spacer thicknesses where antiparallel alignment occurred, the Fe/Cr/Fe system can exhibit a giant magnetoresistance (GMR) effect, that is, an anomalously large change in resistance when a magnetic field is applied. The potential technological importance of the GMR effect to magnetic sensing and magnetic information storage added further impetus to the already rapidly growing area of research in magnetic multilayers.

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Introduction of spin torques

10.1093/oso/9780198787075.003.0019 ◽

2017 ◽

Author(s):

T. Kimura

Keyword(s):

Angular Momentum ◽

Giant Magnetoresistance ◽

Spontaneous Magnetization ◽

Magnetic Domain ◽

Magnetic Multilayers ◽

Transfer Effect ◽

Spin Transfer Torque ◽

Spin Transfer ◽

Spin Angular Momentum ◽

Spin Torques

This chapter discusses the spin-transfer effect, which is described as the transfer of the spin angular momentum between the conduction electrons and the magnetization of the ferromagnet that occurs due to the conservation of the spin angular momentum. L. Berger, who introduced the concept in 1984, considered the exchange interaction between the conduction electron and the localized magnetic moment, and predicted that a magnetic domain wall can be moved by flowing the spin current. The spin-transfer effect was brought into the limelight by the progress in microfabrication techniques and the discovery of the giant magnetoresistance effect in magnetic multilayers. Berger, at the same time, separately studied the spin-transfer torque in a system similar to Slonczewski’s magnetic multilayered system and predicted spontaneous magnetization precession.

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Restructured single parabolic band model for quick analysis in thermoelectricity

npj Computational Materials ◽

10.1038/s41524-021-00587-5 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Jianbo Zhu ◽

Xuemei Zhang ◽

Muchun Guo ◽

Jingyu Li ◽

Jinsuo Hu ◽

...

Keyword(s):

Fermi Level ◽

Carrier Concentration ◽

Carrier Mobility ◽

Optimization Design ◽

State Of The Art ◽

Band Model ◽

Carrier Effective Mass ◽

Intermediate Variables ◽

Level Calculation ◽

Spb Model

AbstractThe single parabolic band (SPB) model has been widely used to preliminarily elucidate inherent transport behaviors of thermoelectric (TE) materials, such as their band structure and electronic thermal conductivity, etc. However, in the SPB calculation, it is necessary to determine some intermediate variables, such as Fermi level or the complex Fermi-Dirac integrals. In this work, we establish a direct carrier-concentration-dependent restructured SPB model, which eliminates Fermi-Dirac integrals and Fermi level calculation and emerges stronger visibility and usability in experiments. We have verified the reliability of such restructured model with 490 groups of experimental data from state-of-the-art TE materials and the relative error is less than 2%. Moreover, carrier effective mass, intrinsic carrier mobility and optimal carrier concentration of these materials are systematically investigated. We believe that our work can provide more convenience and accuracy for thermoelectric data analysis as well as instructive understanding on future optimization design.

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