Induzierte Domänenbewegung in magnetischen Tunnelkontakten mit sinusförmiger Kleinfeldmodulation
Induzierte Domänenbewegung in magnetischen Tunnelkontakten mit sinusförmiger Kleinfeldmodulation
First measurements on Barkhausen - noise from magnetic tunnel junctions arepresented. A low frequency magnetic field was applied to the magnetic thin film layers andthen the temporary changes in the voltage signal of the junction were measured as spectralnoise density. The alternativg magnetic field...
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Personal Name(s): | Schmitz, Rolf (Corresponding author) |
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Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2002
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Physical Description: |
II, 121 p. |
Document Type: |
Report Book |
Research Program: |
Addenda |
Series Title: |
Berichte des Forschungszentrums Jülich
3925 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
First measurements on Barkhausen - noise from magnetic tunnel junctions arepresented. A low frequency magnetic field was applied to the magnetic thin film layers andthen the temporary changes in the voltage signal of the junction were measured as spectralnoise density. The alternativg magnetic field causes a temporary change of themagnetization in the ferromagnetic layers. These changes influence the behavior of theresistance directly and the TMR - effect, respectively. With this method it was possible todraw conclusions on the switching behavior of the magnetic domains in each magneticlayer.Magnetic tunnel junctions with a tri-layer system made of Co/Al$_{2}$O$_{3}$/NiFe have beenfabricated. The aluminum oxide barrier was fabricated using a mercury - low pressurelamp which was able to produce oxygen radicals as well as ozone from pure oxygen gas.This successful preparation method is concerned to be an alternative to the commonly usedplasma oxidation. All of the tunnel junctions showed a clear tunneling behavior based onthe nonlinear current - voltage characteristics. The tunneling magnetoresistance effect ofthe junctions made with the UV-light were in the range of 10 - 20 % at room temperature.The magnetic switching fields have been measured to 0,5 and 2 kA/m for the soft- andhard magnetic layers respectively.In order to characterize the tunnel barrier, noise measurements at different appliedmagnetic fields were made. No significant changes were observed in the spectra of the UV- light oxidized and the plasma oxidized tunnel junctions.The surface roughness of Co and Al were also studied by X-ray diffraction andscanning force microscopy measurements. These showed clearly that a low Ar pressureduring sputtering is responsible for the excellent smoothness. An rms - roughness wasfound which was less than 0,2 nm.TMR ratios of the UV - light oxidized barriers were investigated depending on thebias - voltage and temperature.Furthermore, the oxygen pressure was varied which was applied during the one houroxidation procedure of the aluminum. An optimal condition could be found at p = 10 mbarO$_{2}$. Using this value the maximum TMR- ratios were received. |