SEMPA Studies of Exchange Coupling in Magnetic Multilayers

MRS Bulletin ◽  
1995 ◽  
Vol 20 (10) ◽  
pp. 30-33 ◽  
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.

Effect of Hybridization on Exchange Coupling in Magnetic Multilayers

1993 ◽  
Vol 313 ◽  
Author(s):  
J. Mathon ◽  
M.A. Villeret ◽  
J.M. Mander ◽  
D.M. Edwards ◽  
R.B. Muniz
Keyword(s):  
Transition Metal ◽  
Exchange Coupling ◽  
Magnetic Multilayers ◽  
Size Quantization ◽  
Conduction Electrons ◽  
Long Period ◽  
Oscillatory Coupling

ABSTRACTAn earlier theory of the exchange coupling between two ferromagnets separated by a nonmagnetic transition metal spacer was based on size quantization of the electron energies in the spacer. It is now generalized to include the effect of hybridization between the conduction and d bands both in the ferromagnet and in the spacer. The new theory thus unifies the approach based on coupling via d electrons, valid for transition metal spacers, with RKKY-type theories for noble and simple metals which rely on coupling via conduction electrons. The theory is applied to calculate the period and strength of the long-period oscillatory coupling in (001) CO/Cu trilayer.

scholarly journals Control of the noncollinear interlayer exchange coupling

2020 ◽  
Vol 6 (48) ◽  
pp. eabd8861
Author(s):  
Zachary R. Nunn ◽  
Claas Abert ◽  
Dieter Suess ◽  
Erol Girt
Keyword(s):  
Exchange Coupling ◽  
Magnetic Moments ◽  
Interlayer Exchange Coupling ◽  
Magnetic Structures ◽  
Spintronic Devices ◽  
Spacer Layer ◽  
Ferromagnetic Layers ◽  
Almost All ◽  
Interlayer Exchange ◽  
Coupling Angle

Interlayer exchange coupling in transition metal multilayers has been intensively studied for more than three decades and is incorporated into almost all spintronic devices. With the current spacer layers, only collinear magnetic alignment can be reliably achieved; however, controlling the coupling angle has the potential to markedly expand the use of interlayer exchange coupling. Here, we show that the coupling angle between the magnetic moments of two ferromagnetic layers can be precisely controlled by inserting a specially designed magnetic metallic spacer layer between them. The coupling angle is controlled solely by the composition of the spacer layer. Moreover, the biquadratic coupling strength, responsible for noncollinear alignment, is larger than that of current materials. These properties allow for the fabrication and study of not yet realized magnetic structures that have the potential to improve existing spintronic devices.

Microstructure of spin-valve mr sandwiches

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.

Study on the Interfacial Characterization of the Co5/Cu3/Co5 trilayer and Co3/Cu/Co/Cu3/Co/Cu/Co3 Multilayer

2004 ◽  
Vol 19 (3) ◽  
pp. 741-745 ◽  
Author(s):  
Xiaoyu Yuan ◽  
Xiaofang Bi ◽  
Jiaxiang Shang ◽  
Huibin Xu
Keyword(s):  
Exchange Coupling ◽  
Giant Magnetoresistance ◽  
Zero Field ◽  
Local Spin Density Approximation ◽  
Discrete Variational Method ◽  
Ferromagnetic Layers ◽  
Calculation Results ◽  
Spin Dependent Scattering ◽  
The Moment

Comprehensive results are presented on the influence of interfaces on electronic structure and giant magnetoresistance (GMR). Two structures were calculated for Co5/Cu3/Co5 and Co3/Cu/Co/Cu3/Co/Cu/Co3, where numbers stand for monolayer numbers of atoms, by employing the discrete variational method in the framework of the local spin density approximation. It has been found that the electron spin-dependent scattering is very strong at the interfaces compared to the interiors of the ferromagnetic layers, independent of the moment alignment configuration. The calculation results of total energy for various magnetization configuration revealed that antiferromagnetic exchange coupling was present between any of the ferromagnetic layers separated by Cu layers at zero field in the Co3/Cu/Co/Cu3/Co/Cu/Co3. The evaluated GMR ratio for the Co3/Cu/Co/Cu3/Co/Cu/Co3 (about 35.1%) was much larger than that of the Co5/Cu3/Co5 (about 21.0%), indicating large GMR effect could be expected with more interfaces when the thicknesses were the same. The result also indicated that the negative polarization of 4s electrons could reduce the GMR effect.

Magneto-Optical Investigation of Thin-Film Magnetic Structures

2013 ◽  
Vol 543 ◽  
pp. 247-250 ◽  
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Elena Enaldieva ◽  
Tamerlan T. Magkoev ◽  
Anatolij Turiev ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Giant Magnetoresistance ◽  
Magnetic Interaction ◽  
Antiferromagnetic Interaction ◽  
Multilayer Structures ◽  
Optical Investigation ◽  
Magnetic Structures ◽  
Magnetic Layers ◽  
Spacer Layer ◽  
Nonmagnetic Spacer

After the discovery of antiferromagnetic interaction [, giant magnetoresistance [ and oscillating magnetic interaction [, the exchange coupling between magnetic layers across the conductive nonmagnetic spacer layer in multilayer structures have been attracted much attention [4-.

Large magnetoresistance in oxide based ferromagnet / superconductor spin switches

2005 ◽  
Vol 887 ◽  
Author(s):  
V. Peña ◽  
N. Nemes ◽  
C. Visani ◽  
J. Garcia-Barriocanal ◽  
F. Bruno ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Giant Magnetoresistance ◽  
Relative Orientation ◽  
Length Scale ◽  
Magnetoresistance Effect ◽  
Superconducting Layer ◽  
Spin Polarized ◽  
Ferromagnetic Layers ◽  
Parallel Configuration

ABSTRACTWe report large magnetoresistance (in excess of 1000%) in ferromagnet / superconductor / ferromagnet structures made of La0.7Ca0.3MnO3 and YBa2Cu3O7 in the current in plane (CIP) geometry. This magnetoresistance has many of the ingredients of the giant magnetoresistance of metallic superlattices: it is independent on the angle between current and magnetic field, depends on the relative orientation of the magnetization in the ferromagnetic layers, and takes very large values. The origin is enhanced scattering at the F/S interface in the anti parallel configuration of the magnetizations. Furthermore, we examine the dependence of the magnetoresistance effect on the thickness of the superconducting layer, and show that the magnetoresistance dies out for thickness in excess of 30 nm, setting a length scale for the diffusion of spin polarized quasiparticles.

Exchange Coupling and Giant Magnetoresistance in Electrodeposited Co/Cu Multilayers

1997 ◽  
Vol 475 ◽  
Author(s):  
A. Dinia ◽  
K. Rahmouni ◽  
G. Schmerber ◽  
H. El Fanity ◽  
M. Bouanani ◽  
...  
Keyword(s):  
Exchange Coupling ◽  
Giant Magnetoresistance ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Magnetoresistance Effect ◽  
X Ray ◽  
Resistivity Measurements ◽  
Fee Structure ◽  
Giant Magnetoresistance Effect ◽  
Spacer Layer

ABSTRACTWe present the results of the transport and magnetization measurements of electrodeposited Co/Cu multilayers grown in a single electrolyte based on C0SO4, H3BO3 and CuSO4. The samples are deposited on glass substrate covered by a 500 Å thick Cu buffer layer. X-ray diffraction performed on the samples shows fee structure of both Co and Cu layers with preferential (111) orientation. Resistivity measurements show a giant magnetoresistance effect of about 4% at room temperature for multilayers with Co and Cu thickness between 4 nm ≤ tco ≤ 6 nm and 3 nm ≤ tcu ≤4 nm respectively. For Co thickness tCo ≤ 15 nm, the magnetoresistance completely vanishes indicating that there is no more continuous Co layer. The indirect antiferromagnetic exchange coupling between magnetic Co layers is relatively large for 4 nm thick Cu spacer layer and gives rise to a temperature dependence of about 30% between room temperature and 4.2 K.

EFFECTIVE BAND MODEL OF GIANT MAGNETORESISTANCE

2001 ◽  
Vol 08 (03n04) ◽  
pp. 271-279 ◽  
Author(s):  
K. WARDA ◽  
L. WOJTCZAK ◽  
D. BALDOMIR ◽  
M. PEREIRO
Keyword(s):  
Fermi Level ◽  
Transport Properties ◽  
Effective Mass ◽  
Effective Potential ◽  
Giant Magnetoresistance ◽  
Magnetic Multilayers ◽  
Band Model ◽  
Mass Approximation ◽  
Electronic Current ◽  
Ferromagnetic Layers

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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