Magnetic tunneling junction based magnetic field sensors: Role of shape anisotropy versus free layer thickness

Al 2 O 3 - and MgO-based magnetic tunnel junction (MTJ) sensors were designed and fabricated using microfabrication techniques. This study revealed that in the case of Al 2 O 3 -based sensors, the shape anisotropy in the free NiFe electrode resulted in a linear and hysteresis-free tunneling magnetor...

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Bibliographic Details
Published in:Journal of applied physics 2011-04, Vol.109 (7), p.07C731-07C731-3
Main Authors: Shah, Lubna R., Bhargava, Nupur, Kim, Sangcheol, Stearrett, Ryan, Kou, Xiaoming, Sun, Xiaolian, Sun, Shouheng, Kolodzey, James, Nowak, Edmund R., Xiao, John Q.
Format: Article
Language:English
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Summary:Al 2 O 3 - and MgO-based magnetic tunnel junction (MTJ) sensors were designed and fabricated using microfabrication techniques. This study revealed that in the case of Al 2 O 3 -based sensors, the shape anisotropy in the free NiFe electrode resulted in a linear and hysteresis-free tunneling magnetoresistance (TMR) curve. These sensors exhibited TMR values between 27% and 30% and sensitivity up to 0.4%/Oe over a magnetic field range of −40 to 40 Oe. In the case of CoFeB/MgO/CoFeB MTJ sensors, shape anisotropy alone was not sufficient to achieve a linear and hysteresis-free MR response. A superparamagnetic free layer was used to achieve the desired sensor response. MgO-based sensors had about 90% TMR and 1.1%/Oe sensitivity over the same field range as Al 2 O 3 -based MTJs.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.3563096