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A PHEB magnetometer with record thick multiexchange-biased sensor layer
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. KTH. (Applied spintronics)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this paper, we develop material stacks for the fabrication of a magnetometer with multiple exchange-biased layers reaching thicknesses exceeding previous attempts in the literature. The benets of such thick sensor layers is demonstrated in terms of the low noise based on the decreasing resistance without an eect on device sensitivity. The thick sensor layers of [IrMn(15nm)/NiFe(150nm)]7/IrMn(15nm), as a novel multiple-biasing scheme, is able to stabilize up to fourteenfold biased interfaces. We measured the sensitivity and noise of these devices and report a eld detectivity of 600 pT/pHz at 2 Hz. Our results describe a reliable technique for the fabrication of thick prototype magnetometers based on the exchange-bias mechanism.

Keyword [en]
AMR, Magnetic sensor, Ferromagnetic, Antiferromagnetic, NiFe, IrMn, exchange bias
National Category
Condensed Matter Physics
Research subject
Materials Science and Engineering; Physics
Identifiers
URN: urn:nbn:se:kth:diva-187235OAI: oai:DiVA.org:kth-187235DiVA: diva2:929319
Note

QC 20160519

Available from: 2016-05-18 Created: 2016-05-18 Last updated: 2016-05-19Bibliographically approved
In thesis
1. Fabrication and Characterization of magnetometer for space applications
Open this publication in new window or tab >>Fabrication and Characterization of magnetometer for space applications
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present rapid increase in the number of space missions demands a decrease in the cost of satellite equipment, but also requires the development of instruments that have low power consumption, low weight, and small size.Anisotropic magnetoresistance (AMR) sensors can answer these needs on account of their small size, weight, and power consumption. AMR sensors also produce lower noise than either giant magnetoresistance (GMR) or tunnel magnetoresistance (TMR) devices and are thus more suitable for space applications.The type of AMR sensor developed in this study was a Planar Hall EffectBridge (PHEB) sensor. The FM layer was also coupled with an AFM layer in order to fix the internal magnetization of the FM layer.One technique that was employed in order to meet the low-noise requirement was to make the FM layer thicker than has previously been attempted.In doing so, the exchange bias field between the AFM layer and the FMlayer is no longer high enough to bias the thicker FM layer, so in order to correct this unwanted effect, the material stack was upgraded to two AFM–FM interfaces. With this configuration, it became possible to increase the exchange field by up to 60%. Stronger exchange bias leads to a thicker FMlayer and so to lower noise in the device performance. Another strategy that was used to lower the resistance of the device was to implement an NiFeX alloy instead of the standard NiFe. NiFeX consists of an alloy of NiFe andCu, Ag, or Au; the last of these is known to have very low resistivity.This solution leads to a significant lowering of the device’s resistance. A recent technological advance used to fabricate devices with lower resistance is to deposit a multilayer of AFM–FM.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 73 p.
Series
TRITA-ICT, 2016:15
Keyword
AMR, Magnetic sensor, Ferromagnetic, Antiferromagnetic, NiFe, IrMn, exchange bias.
National Category
Condensed Matter Physics
Research subject
Physics; Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-187237 (URN)ISBN 978-91-7595-982-5 (ISBN)
Public defence
2016-06-10, Sal C, Isafjordsgatan 26, Kista, 13:01 (English)
Opponent
Supervisors
Available from: 2016-05-19 Created: 2016-05-18 Last updated: 2016-05-19Bibliographically approved

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