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Fabrication and Characterization of magnetometer for space applications
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. KTH. (Applied spintronics)
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 [en]
AMR, Magnetic sensor, Ferromagnetic, Antiferromagnetic, NiFe, IrMn, exchange bias.
National Category
Condensed Matter Physics
Research subject
Physics; Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-187237ISBN: 978-91-7595-982-5 OAI: oai:DiVA.org:kth-187237DiVA: diva2:929331
Public defence
2016-06-10, Sal C, Isafjordsgatan 26, Kista, 13:01 (English)
Opponent
Supervisors
Note

QC 20170302

Available from: 2016-05-19 Created: 2016-05-18 Last updated: 2017-03-02Bibliographically approved
List of papers
1. Thick Double-Biased IrMn/NiFe/IrMn Planar Hall Effect Bridge Sensors
Open this publication in new window or tab >>Thick Double-Biased IrMn/NiFe/IrMn Planar Hall Effect Bridge Sensors
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2014 (English)In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 50, no 11, 4006104Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a new material stack for planar Hall effect bridge (PHEB) sensors and a detailed investigation of the sensitivity and noise properties of PHEB sensors made from these. The sputter deposited material stack was based on a ferromagnetic (FM) NiFe sensing layer surrounded by two layers of anti-FM IrMn. This material stack enables implementation of a thick NiFe layer without loss of sensitivity. We present an improvement in detectivity in the PHEB by changing the shape and the materials of the corners between the sensors in a meander shape. A significant reduction of noise also comes from the thick NiFe layer, due to the reduced resistance of the sensor.

Keyword
Anisotropic magnetoresistance (AMR), antiferromagnetic (AFM), ferromagnetic (FM), magnetic anisotropy, magnetic sensor planar Hall effect
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-161568 (URN)10.1109/TMAG.2014.2330846 (DOI)000349465900253 ()2-s2.0-84917692997 (Scopus ID)
Funder
Swedish National Space Board
Note

QC 20150326

Available from: 2015-03-26 Created: 2015-03-13 Last updated: 2017-12-04Bibliographically approved
2. Planar Hall-Effect Bridge Sensor With NiFeX (X = Cu, Ag, and Au) Sensing Layer
Open this publication in new window or tab >>Planar Hall-Effect Bridge Sensor With NiFeX (X = Cu, Ag, and Au) Sensing Layer
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2015 (English)In: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 51, no 11, 4005404Article in journal (Refereed) Published
Abstract [en]

This paper presents a new material alloy for planar Hall-effect bridge (PHEB) sensors and the accurate analysis of the resistance and sensitivity of these materials. The sensing layer is based on NiFeX (X = Cu, Ag, and Au). These alloys have a lower resistance without a significant loss of sensitivity. The presented PHEB sensors with NiFeX sensing layer show a coercivity of 1.7 Oe, lower than that of PHEB sensors with NiFe sensing layers, which have coercivities of 2.2 Oe.

Place, publisher, year, edition, pages
IEEE Press, 2015
Keyword
Anisotropic magnetoresistance (AMR), antiferromagnetic (AFM), ferromagnetic (FM), magnetic anisotropy, magnetic sensor planar Hall effect
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-179169 (URN)10.1109/TMAG.2015.2451216 (DOI)000364770500327 ()2-s2.0-84946121921 (Scopus ID)
Conference
IEEE International Magnetics Conference (Intermag), MAY 11-15, 2015, Beijing, PEOPLES R CHINA
Note

QC 20151214

Available from: 2015-12-14 Created: 2015-12-11 Last updated: 2017-12-01Bibliographically approved
3. Order of magnitude increase in AMR sensor layer thickness through multi-interface exchange biasing
Open this publication in new window or tab >>Order of magnitude increase in AMR sensor layer thickness through multi-interface exchange biasing
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We demonstrate an order of magnitude increase in total ferromagnetic layer thickness in magnetron sputtered and exchange-biased multilayers of [IrMn(15nm)/NiFe(t)]N/IrMn(15nm) with t=50{200 nm and N=1{7. Wend a strong exchange-bias eld (Heb) and a low coercivity (Hc) in all multilayers, with a gradual improvement with increasing number of multilayer repetitions. All stacks with t=50{150 nm exhibit single-step switching,while the stacks with the thickest NiFe show signs of multistep switching. Four-point magnetotransport measurements show values for the anisotropic magnetoresistance (AMR) of about 3% in all stacks. We determine the lm roughness and mean grain size using Atomic Force Microscopy and nd a direct correlation between Heb and the grain size on the one hand, and Hc and the inverse of the roughness on the other. Our results directly demonstrate the feasibility

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-187232 (URN)
Note

QC 20160519

Available from: 2016-05-18 Created: 2016-05-18 Last updated: 2016-05-19Bibliographically approved
4. A PHEB magnetometer with record thick multiexchange-biased sensor layer
Open this publication in new window or tab >>A PHEB magnetometer with record thick multiexchange-biased sensor layer
(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
AMR, Magnetic sensor, Ferromagnetic, Antiferromagnetic, NiFe, IrMn, exchange bias
National Category
Condensed Matter Physics
Research subject
Materials Science and Engineering; Physics
Identifiers
urn:nbn:se:kth:diva-187235 (URN)
Note

QC 20160519

Available from: 2016-05-18 Created: 2016-05-18 Last updated: 2016-05-19Bibliographically approved
5. Gamma radiation hardness of PHEB magnetometers
Open this publication in new window or tab >>Gamma radiation hardness of PHEB magnetometers
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We study planar Hall eect bridge (PHEB) sensors under gamma ray irradiation to investigate their potential use in space applications. We fabricate and characterize a wide range of PHEBs with dierent geometries to evaluate the eects of irradiation. We observe no signicant change in performance for the sensors irradiated by gamma rays with doses up to 100 krad. However, a dramatic increase in sensor noise and a corresponding loss in detectivity are observed after 300 krad of radiation. Our results indicate that PHEB magnetometers can operate for at least 5 years in orbit.

National Category
Condensed Matter Physics
Research subject
Physics; Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-187236 (URN)
Note

QC 20160519

Available from: 2016-05-18 Created: 2016-05-18 Last updated: 2016-05-19Bibliographically approved

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