Calculation of Magnetization Processes in Multilayers with Antiferromagnetic Coupling between Adjacent Layers

1989 ◽  
Vol 151 ◽  
Author(s):  
B. Dieny ◽  
J. P. Gavigan ◽  
J. P. Rebouillat
Keyword(s):  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Antiferromagnetic Coupling ◽  
Propagation Mechanism ◽  
Multilayer Systems ◽  
Number Of Layers ◽  
Magnetization Processes

ABSTRACTThis paper presents calculations of hysteresis loops in ferromagnetic multilayer systems of cubic or uniaxial anisotropy with antiferromagnetic coupling between adjacent layers. The case of a bilayer has been systematically studied as a function of the strenght of the anisotropy. The two limiting cases corresponding to either a coherent rotation of the magnetization or to a non-dissipative nucleation-propagation mechanism are investigated. The influence of the number of layers is also discussed.

Magnetization Processes Analysis in Co-Cu Superlattices

1989 ◽  
Vol 151 ◽  
Author(s):  
J. P. Rebouillat ◽  
G. Fillion ◽  
B. Dieny ◽  
A. Cebollada ◽  
J. M. Gallego ◽  
...  
Keyword(s):  
Hysteresis Loops ◽  
Antiferromagnetic Coupling ◽  
Magnetization Measurements ◽  
The Individual ◽  
Magnetization Processes

ABSTRACTThe analysis of the magnetization measurements performed on two Co-Cu multilayers confirm the antiferromagnetic coupling already observed with neutron experiments. Both exchange and anisotropy energies are taken into account and estimated. Their competitive role in the individual moment orientation leads to typical moment arrangements and hysteresis loops.

GMR, Structural, and Magnetic Studies in NiFeCo/Ag Multilayer thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
J.D. Jarratt ◽  
J.A. Barnard
Keyword(s):  
Giant Magnetoresistance ◽  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Film Plane ◽  
Film Structure ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Lower Temperature ◽  
Deposited Films

ABSTRACTGiant Magnetoresistance (GMR), crystal structure, and magnetic properties have been investigated in a series of sputtered Ni66Fe16Co18/Ag multilayer films with induced uniaxial anisotropy. The film thickness ranges studied were 20 and 25 Å for NiFeCo, and 25 to 50 Å for Ag. GMR was only evident in the films after post-deposition annealing. This onset of GMR is thought to be due to the breaking up of the NiFeCo layers into ferromagnetic platelets or islands by the immiscible Ag diffusing perpendicular to the film plane along the grain boundaries. The magnitude and field sensitivity of the GMR was dependent on the annealing time and temperature. High angle x-ray diffraction (HXRD) was used to reveal the overall film structure and growth texture and low angle XRD (LXRD) was used to investigate the quality of the multilayer structures. M-H hysteresis loops revealed in-plane uniaxial anisotropy in as-deposited films which is eventually eliminated with annealing. The easy axis squareness experiences a pronounced decrease with lower temperature annealing, but then increases slightly with annealing temperature.

Spin Glassiness and Ferromagnetism in Disordered Ni-Mn Alloys

1982 ◽  
Vol 19 ◽  
Author(s):  
James S. Kouvel
Keyword(s):  
Spin Glass ◽  
Critical Field ◽  
Curie Point ◽  
Magnetic Measurements ◽  
Spontaneous Magnetization ◽  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Initial Susceptibility ◽  
Unidirectional Anisotropy ◽  
Glass Properties

ABSTRACTFrom magnetic measurements, the alloy Ni78Mn22 is found to undergo a field-induced transition from spin glassiness to ferromagnetism at a critical field that decreases from ∼140 Oe to zero as the temperature is raised from 4.2 K to 40 K, the ferromagnetic Curie point being ∼270 K. The alloy Ni74Mn26 is found to transform at 80 K from a spin glass to a state of infinite initial susceptibility but no spontaneous magnetization and to remain so up to 155 K, where it becomes paramagnetic. The spin-glass properties of Ni78Mn22 below 40 K and of Ni74Mn26 below 80 K include displaced hysteresis loops produced by cooling in a field. The changes in the hysteresis loops upon subsequent warming correspond to a gradual conversion of a unidirectional anisotropy to a uniaxial anisotropy.

Giant Magnetoresistance in As-Sputter-Deposited Au/NiFe Multilayer Thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
W. Y. Lee ◽  
G. Gorman ◽  
R. Savoy
Keyword(s):  
Thin Films ◽  
Exchange Coupling ◽  
Giant Magnetoresistance ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Multilayer Films ◽  
Antiferromagnetic Coupling ◽  
Multilayer Thin Films ◽  
Glass Substrates ◽  
Sputter Deposited

ABSTRACTGiant magnetoresistance with low saturation fields (Hs’s) is reported in Au and permalloy (Ni0.82Fe0.18) or Co-doped permalloy multilayer thin films as-deposited on Ta-overcoated Si and glass substrates. A ΔR/R as high as 4.0% with ≈25 Oe Hs was observed at 295 K for the film consisting of 10 layers of 24 Å Au/13 Å Ni0.82Fe0.18 deposited on a 3 Å Ta-overcoated glass at 50 °C. A Hs value as low as ≈20 Oe with a 15% smaller ΔR/R has been observed for the films with a thicker (e.g., 50 Å) Ta underlayer. Magnetic hysteresis loops of these films indicate the presence of antiferromagnetic exchange coupling between the Ni0.82Fe0.18 layers. This exchange coupling is much smaller for the multilayer films without the Ta underlayer, resulting in a 6x smaller ΔR/R and lOx larger Hs observed for these films. Results of x-ray diffraction analysis indicate stronger (111) texturing for the multilayer films with a Ta underlayer, consistent with the stronger antiferromagnetic coupling between the the Ni0.82Fe0.18 layers in the film. The addition of 2–10 % Co moderately increases the ΔR/R value, but also increases substantially the Hs (up to ≈200 Oe).

A study on pinned layer magnetization processes in different antiferromagnetic coupling systems of spin-valves

2000 ◽  
Vol 87 (9) ◽  
pp. 5729-5731 ◽  
Author(s):  
Zhijun Yang ◽  
Dehua Han ◽  
Sining Mao ◽  
Hong Wang ◽  
Ghanim Al-Jumaily ◽  
...  
Keyword(s):  
Spin Valves ◽  
Antiferromagnetic Coupling ◽  
Magnetization Processes ◽  
Layer Magnetization

IRREVERSIBLE SUSCEPTIBILITY OF INITIAL MAGNETIZATION CURVES DEFINED BY ENERGY CONSIDERATION

2007 ◽  
Vol 21 (21) ◽  
pp. 3707-3717 ◽  
Author(s):  
G. GOEV ◽  
V. MASHEVA ◽  
M. MIKHOV ◽  
J. GESHEV
Keyword(s):  
Magnetic Field ◽  
Hysteresis Loops ◽  
Model System ◽  
Magnetization Curves ◽  
Maximum Magnetic Field ◽  
Initial Magnetization ◽  
Curve Method ◽  
Energy Consideration ◽  
Minor Hysteresis Loops ◽  
Magnetization Processes

A method for the estimation of reversible and irreversible susceptibilities of initial magnetization curves has been developed. It deals with the energy necessary for magnetizing and demagnetizing the sample, but neither with the nature of the magnetization processes nor with a specific type of anisotropy, so it could be applied for a wide variety of real materials. A set of minor hysteresis loops of an initially demagnetized sample, plotted with progressively increasing maximum magnetic field, has been used. The obtained results showed excellent agreement with those calculated by the remanence curve method for a Stoner–Wohlfarth model system.

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