Microstructure of spin-valve mr sandwiches

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.

Download Full-text

Giant Magnetoresistance Induced by Ultrathin Magnetic Layers

MRS Proceedings ◽

10.1557/proc-475-99 ◽

1997 ◽

Vol 475 ◽

Author(s):

G.J. Strijkers ◽

H.J.M. Swagten ◽

A.H.M. Mettler ◽

M.M.H. Willekens ◽

W.J.M. De Jonge

Keyword(s):

Giant Magnetoresistance ◽

Spin Valve ◽

Short Length ◽

Spin Valves ◽

Length Scale ◽

Magnetic Layers ◽

Ferromagnetic Layers ◽

Experimental Tool ◽

Spin Dependent Scattering

ABSTRACTWe introduce an interface selective structure, composed of a spin-valve on top of which a thick nonmagnetic back layer is deposited as a straightforward experimental tool to measure the GMR induced by ultrathin magnetic layers. The interface selectivity of spin-dependent scattering is evidenced by calculations and illustrated in both Co/Cu/Co and Ni80Fe20/Cu/Ni80Fe20 spin-valves by an almost discontinuous behavior in the GMR ratio. The temperture dependence of the extremely short length scale associated with this discontinuity is discussed in relation to the structure of ultrathin ferromagnetic layers.

Download Full-text

DEPENDENCE OF GIANT MAGNETORESISTANCE ON THE THICKNESS OF MAGNETIC AND NON-MAGNETIC LAYERS IN DUAL SPIN VALVES

Modern Physics Letters B ◽

10.1142/s0217984904006949 ◽

2004 ◽

Vol 18 (09) ◽

pp. 355-365 ◽

Cited By ~ 2

Author(s):

YONG WANG ◽

MING XU ◽

ZHENHONG MAI

Keyword(s):

Giant Magnetoresistance ◽

Classical Model ◽

Spin Valve ◽

Magnetic Layer ◽

Spin Valves ◽

Experimental Result ◽

Magnetic Layers ◽

Ferromagnetic Layers ◽

Hole Effect ◽

Good Agreement

Based on the previous semi-classical model, we have performed calculation of the giant magnetoresistance (GMR) as a function of the thickness of the top/bottom or center ferromagnetic layers and the non-magnetic layer in dual spin valves. Our results are in good agreement with that reported in experiment, i.e., a GMR maximum is observed when the thickness of the top/bottom magnetic layer is at 20 ~ 40 Å; the GMR value decreases monotonically with the increase of the non-magnetic layer thickness. By considering the "pin-hole" effect, the variation of GMR versus the thickness of the center magnetic layer is also found to be consistent with the experimental result. These calculations will be helpful in the design of high-quality spin-valve structures.

Download Full-text

Exchange Bias and Spin-Valve Giant Magnetoresistance in Multilayers with Mn-17 mol%Ir-2 mol%Pt Antiferromagnetic Layer

MATERIALS TRANSACTIONS ◽

10.2320/matertrans.43.893 ◽

2002 ◽

Vol 43 (5) ◽

pp. 893-896

Author(s):

Dong-Min Jeon ◽

Yoon-Sik Kim ◽

Suk-Min Na ◽

Jae-Chul Ro ◽

Dae-Ho Yoon ◽

...

Keyword(s):

Exchange Bias ◽

Giant Magnetoresistance ◽

Spin Valve ◽

Antiferromagnetic Layer

Download Full-text

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.

Download Full-text

EFFECTIVE BAND MODEL OF GIANT MAGNETORESISTANCE

Surface Review and Letters ◽

10.1142/s0218625x01001026 ◽

2001 ◽

Vol 08 (03n04) ◽

pp. 271-279 ◽

Cited By ~ 6

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.

Download Full-text

Giant Magnetoresistance Properties of Spin Valve Films in Current-perpendicular-to-plane Geometry.

Journal of the Magnetics Society of Japan ◽

10.3379/jmsjmag.25.807 ◽

2001 ◽

Vol 25 (4−2) ◽

pp. 807-810 ◽

Cited By ~ 10

Author(s):

K. Nagasaka ◽

Y. Seyama ◽

Y. Shimizu ◽

A. Tanaka

Keyword(s):

Giant Magnetoresistance ◽

Spin Valve ◽

Plane Geometry ◽

Current Perpendicular To Plane

Download Full-text

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.

Download Full-text