Microstructural origin of giant magnetoresistance in a new sensor structure based on NiFe/Ag discontinuous multilayer thin films

1994 ◽  
Vol 75 (10) ◽  
pp. 6382-6384 ◽  
Author(s):  
M. A. Parker ◽  
T. L. Hylton ◽  
K. R. Coffey ◽  
J. K. Howard
Keyword(s):  
Thin Films ◽  
Giant Magnetoresistance ◽  
Multilayer Thin Films ◽  
Sensor Structure

Giant magnetoresistance in Co/Cu multilayer thin films

1993 ◽  
Vol 126 (1-3) ◽  
pp. 516-518 ◽  
Author(s):  
P.J. Grundy ◽  
R.J. Pollard ◽  
M.E. Tomlinson
Keyword(s):  
Thin Films ◽  
Giant Magnetoresistance ◽  
Multilayer Thin Films

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).

Giant Magnetoresistance at Low Fields in Discontinuous NiFe-Ag Multilayer Thin Films

Science ◽  
1993 ◽  
Vol 261 (5124) ◽  
pp. 1021-1024 ◽  
Author(s):  
T. L. Hylton ◽  
K. R. Coffey ◽  
M. A. Parker ◽  
J. K. Howard
Keyword(s):  
Thin Films ◽  
Giant Magnetoresistance ◽  
Multilayer Thin Films

scholarly journals Models of granular giant magnetoresistance multilayer thin films

1996 ◽  
Vol 32 (2) ◽  
pp. 590-598 ◽  
Author(s):  
J.O. Oti ◽  
S.E. Russek ◽  
S.C. Sanders ◽  
R.W. Cross
Keyword(s):  
Thin Films ◽  
Giant Magnetoresistance ◽  
Multilayer Thin Films

Stress in Giant Magnetoresistive Ni66Fe16Co18/Ag Multilayer thin Films

1994 ◽  
Vol 356 ◽  
Author(s):  
J.D. Jarratt ◽  
J.A. Barnard
Keyword(s):  
Thin Films ◽  
Compressive Stress ◽  
Giant Magnetoresistance ◽  
Uniaxial Anisotropy ◽  
Structural Evolution ◽  
Film Plane ◽  
Film Stress ◽  
Bilayer Film ◽  
Multilayer Thin Films ◽  
Thin Film Stress

AbstractThin film stress has been measured in (Ni66Fe16Co18 25 Å/Ag 50 Å) multilayer thin films that exhibit annealing-induced giant magnetoresistance (GMR) known as ‘discontinuous’ GMR1. This GMR results when NiFeCo layers are broken up into discontinuous ferromagnetic islands or platelets by immiscible Ag atom grain boundary diffusion normal to the film plane. As-deposited films display no GMR and are in compression. An MR value of 5 % with a relatively sharp profile can be induced in a ten bilayer sample annealed at 400°C for 15 min. Annealing generally results in a decrease in the as-deposited compressive stress and can result in tensile stress at high enough temperatures. Interestingly, at the annealing temperatures corresponding to the maximum induced GMR, there is a plateau in the otherwise monotonic decrease in compressive stress with increasing temperature.Stress-temperature plots reveal a plateau in the stress value during the heating of a ten bilayer sample due to plastic deformation in the film via densification. Isothermal stress-time plots done on a single sample show increasing compressive stress relief after each successively higher temperature anneal. The stress was also measured in a single bilayer film with the same volume of film as in a ten bilayer sample but far fewer interfaces. High and low angle x-ray diffraction (HXRD, LXRD) was used to reveal the structural evolution with annealing. Magnetic (M-H) hysteresis measurements revealed increasing coercivity and decreasing induced as-deposited in-plane magnetic uniaxial anisotropy with annealing temperature.

Magnetostatically induced giant magnetoresistance in patterned NiFe/Ag multilayer thin films

1995 ◽  
Vol 67 (8) ◽  
pp. 1154-1156 ◽  
Author(s):  
T. L. Hylton ◽  
M. A. Parker ◽  
K. R. Coffey ◽  
J. K. Howard ◽  
R. Fontana ◽  
...  
Keyword(s):  
Thin Films ◽  
Giant Magnetoresistance ◽  
Multilayer Thin Films

Characterization of reactive phase formation in sputter-deposited Ni/Al multilayer thin films using TEM

1996 ◽  
Vol 54 ◽  
pp. 1000-1001
Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Dark Field ◽  
Nickel Layer ◽  
Multilayer Thin Films ◽  
Cross Sectional ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Constant Heating

The subject of reactive phase formation in multilayer thin films of varying periodicity has stimulated much research over the past few years. Recent studies have sought to understand the reactions that occur during the annealing of Ni/Al multilayers. Dark field imaging from transmission electron microscopy (TEM) studies in conjunction with in situ x-ray diffraction measurements, and calorimetry experiments (isothermal and constant heating rate), have yielded new insights into the sequence of phases that occur during annealing and the evolution of their microstructure.In this paper we report on reactive phase formation in sputter-deposited lNi:3Al multilayer thin films with a periodicity A (the combined thickness of an aluminum and nickel layer) from 2.5 to 320 nm. A cross-sectional TEM micrograph of an as-deposited film with a periodicity of 10 nm is shown in figure 1. This image shows diffraction contrast from the Ni grains and occasionally from the Al grains in their respective layers.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

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