Giant Magnetoresistance Induced by Ultrathin Magnetic Layers

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.

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

2004 ◽  
Vol 18 (09) ◽  
pp. 355-365 ◽  
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.

Dependence of giant magnetoresistance on the thickness of magnetic and non-magnetic layers in spin-valve sandwiches

2000 ◽  
Vol 272 (4) ◽  
pp. 282-288 ◽  
Author(s):  
Ming Xu ◽  
Yong Fan ◽  
Guangming Luo ◽  
Zhenhong Mai
Keyword(s):  
Giant Magnetoresistance ◽  
Spin Valve ◽  
Magnetic Layers

Large Magnetoresistance Variation of Pseudo Spin Valves with Different Nano Oxide Layer Position

2007 ◽  
Vol 1032 ◽  
Author(s):  
Jeong Dae Suh ◽  
C.A. Ross
Keyword(s):  
Surface Roughness ◽  
Oxide Layer ◽  
Multilayer Structure ◽  
Giant Magnetoresistance ◽  
Spin Valves ◽  
Resistance Change ◽  
Nano Oxide ◽  
Shunting Effect ◽  
Spin Dependent Scattering ◽  
Layer Position

AbstractWe have investigated the influence of the nano-oxide layer positions on giant magnetoresistance(GMR) of the NiFe(9nm)/Cu(4nm)/Co(5nm) pseudo spin valves. Nano-oxide layer positions had a several effects on the multilayer structure that changes its magnetotransport behavior. GMR ratio varied between 2.8% and 0.15% depending on the nano-oxide layer positions within the stack. The increase of the GMR ratio was accompanied by increase in resistance change, decrease in sheet resistance, and decrease in surface roughness. These significant variations of GMR ratio was explained by the changes on the spin dependent scattering or current shunting effect. Our results showed that appropriate placement of a nano-oxide layer was essential fo optimize magnetoresistance and properties of spin valves.

Spin Valves in Microelectronics. Review

2021 ◽  
Vol 26 (1) ◽  
pp. 7-29
Author(s):  
Iu.A. Iusipova ◽  
◽  
A.I. Popov ◽  
Keyword(s):  
Giant Magnetoresistance ◽  
Spin Valve ◽  
Random Access ◽  
Cmos Technology ◽  
Work Conditions ◽  
Spin Transfer ◽  
Boolean Logic ◽  
Spin Valves ◽  
Computing Systems ◽  
Technology Scaling

The base element of micromagnetic devices are the layered spin-valve structures. Small sizes, compatibility with the CMOS technology, scaling ability and various work conditions make the spin-valve structures a universal component of modern microelectronics. The purpose of present work is the analysis, systematization and generalization of the data of the work theoretical bases, experimental data and the application of spin valves. In the review, the hard disc drives, random-access magnetoresistive memory, the spin-transfer nano-oscillators, the magnetic biosensors, as well as various computing systems, operating on the principles of stochastic and deterministic logic, have been considered. The key theoretical works devoted to giant magnetoresistance and spin transfer have been used. The data on various types of the hard-disc readheads have been systematized, their architecture and parameters have been compared, and it has been shown how modern scientific research of nanomagnetic phenomena accelerates the growth rate of the recording density. The analysis of modern research devoted to magnetoresistive random access memory has been carried out. The problems of energy efficiency and increasing the degree of the integration for these devices have been discussed. The latest achievements in the field of materials, geometry and the properties of the spin-transfer nano-oscillators, as well as the problems and prospects for the development of this technology have been considered. The analysis of theoretical and experimental works, in which the spin-gate structures have been used to perform the logical operations of Boolean and non-Boolean logic, has been carried out. It has been shown how the probabilistic nature of the unstable switching of spin gates is used in the op-eration of the unconventional computing systems, namely, neuromorphic or Bayesian networks. The principles of operation of the spin valves as magnetic biosensors have been considered and the advantages of their application have been discussed.

scholarly journals Modeling of GMR loops asymmetry in spin valves

2018 ◽  
Vol 185 ◽  
pp. 01011
Author(s):  
Alexander Kurenkov ◽  
Georgy Babaizev ◽  
Nikolay Chechenin
Keyword(s):  
Magnetic Field ◽  
Simple Technique ◽  
Spin Valve ◽  
Hysteresis Loops ◽  
Spin Valves ◽  
Physical Factors ◽  
Regular Shape ◽  
Ferromagnetic Layers ◽  
Insight Into ◽  
Selection Of

The regular shape of the magnetoresistance as a function of applied magnetic field, R(H), is important for numerous spin valves applications. Nevertheless, in many practical studies the shape of the R(H) curve is unpredictably complicated. A simple technique, proposed in this paper, allows interpreting the R(H) features and calculating R(H) curves from known hysteresis loops of ferromagnetic layers, composing spin valves. And vice versa, the shape of the hysteresis loops of the composing ferromagnetic layers can be obtained from R(H) curves.The method does not give an insight into the physical factors determining the shape of hysteresis loops, but it is suitable for prompt selection of promising spin valve stacks. A series of spin valve structures was prepared and their magnetoresistance curves were measured. The analysis of the experimental data demonstrates the capacity of the proposed method.

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.

scholarly journals COMPARATIVE STUDY OF SPIN INJECTION AND TRANSPORT IN Alq3 AND Co–PHTHALOCYANINE-BASED ORGANIC SPIN VALVES

SPIN ◽  
2014 ◽  
Vol 04 (02) ◽  
pp. 1440009 ◽  
Author(s):  
SAYANI MAJUMDAR ◽  
SUKUMAR DEY ◽  
HANNU HUHTINEN ◽  
JOHNNY DAHL ◽  
MARJUKKA TUOMINEN ◽  
...  
Keyword(s):  
Single Molecule ◽  
Giant Magnetoresistance ◽  
Chemical Reactivity ◽  
Spin Injection ◽  
Spin Valve ◽  
Spin Valves ◽  
Half Metallic ◽  
High Expectations ◽  
Spacer Layer ◽  
Spin Polarized

Recent experimental reports suggest the formation of a highly spin-polarized interface ("spinterface") between a ferromagnetic (FM) Cobalt ( Co ) electrode and a metal-phthalocyanine (Pc) molecule. Another report shows an almost 60% giant magnetoresistance (GMR) response measured on Co / H 2 Pc -based single molecule spin valves. In this paper, we compare the spin injection and transport properties of organic spin valves with two different organic spacers, namely Tris(8-hydroxyquinolinato) aluminum ( Alq 3) and CoPc sandwiched between half-metallic La 0.7 Sr 0.3 MnO 3 (LSMO) and Co electrodes. Alq 3-based spin valves exhibit clear and reproducible spin valve switching with almost 35% negative GMR at 10 K, in accordance with previous reports. In contrast, cobalt-pthalocyanine ( CoPc )-based spin valves fail to show clear GMR response above noise level despite high expectations based on recent reports. Investigations of electronic, magnetic and magnetotransport properties of electrode/spacer interfaces of LSMO/ CoPc / Co devices offer three plausible explanations for the absence of GMR: (1) CoPc films are strongly chemisorbed on the LSMO surface. This improves the LSMO magnetic properties but also induces local traps at the LSMO interface for spin-polarized charge carriers. (2) At the Co / CoPc interface, diffusion of Co atoms into the organic semiconductor (OS) layer and chemical reactivity between Co and the OS deteriorates the FM properties of Co . This renders the Co / CoPc interface as unsuitable for efficient spin injection. (3) The presence of heavy Co atoms in CoPc leads to large spin–orbit coupling in the spacer. The spin relaxation time in the CoPc layer is therefore considerably smaller compared to Alq 3. Based on these findings, we suggest that the absence of GMR in CoPc -based spin valves is caused by a combined effect of inefficient spin injection from FM contacts and poor spin transport in the CoPc spacer layer.

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