High-Temperature Magnetic Tunnel Junction Magnetometers Based on L1 0-PtMn Pinned Layer

Magnetometer sensors with high sensitivity based on magnetic tunnel junctions (MTJs) were developed to operate at high temperatures of more than 250 °C. We replaced the commonly used IrMn antiferromagnetic pinning layer with an optimized PtMn antiferromagnet, which has a high magnetic thermal stabil...

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Bibliographic Details
Published in:IEEE sensors letters 2020-05, Vol.4 (5), p.1-4
Main Authors: Ranjbar, Sina, Al-Mahdawi, Muftah, Oogane, Mikihiko, Ando, Yasuo
Format: Article
Language:English
Subjects:
antiferromagnet
exchange bias (EB)
high temperature
Magnetic sensors
magnetic tunnel junction (MTJ)
Magnetic tunneling
magnetometer
Magnetometers
manganese
platinum
Sensitivity
Temperature measurement
Temperature sensors
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Summary:Magnetometer sensors with high sensitivity based on magnetic tunnel junctions (MTJs) were developed to operate at high temperatures of more than 250 °C. We replaced the commonly used IrMn antiferromagnetic pinning layer with an optimized PtMn antiferromagnet, which has a high magnetic thermal stability due to its L1 0 crystal structure. We investigate the effect of measurement temperature on magnetoresistance (MR), exchange bias, and sensitivity in sensor MTJ stacks using either IrMn or PtMn pinning layers. Upon increasing the temperature up to 250 °C, the MR ratio decreases from 146% to 50% for IrMn, and 133% to 80% for PtMn pinning layers. The PtMn-based MTJ sensors sustain a constant sensitivity (4-5 %/Oe) up to 250 °C, compared with IrMn-based sensors, which decrease drastically. This high-temperature performance links to the thermal stability of exchange bias in the pinned layer by using PtMn.
ISSN:2475-1472
2475-1472
DOI:10.1109/LSENS.2020.2991654