Picotesla Magnetic Sensors for Low-Frequency Applications

Author

Liou, S.H. ; Xiaolu Yin ; Russek, S.E. ; Heindl, R. ; da Silva, F.C.S. ; Moreland, James ; Pappas, D.P. ; Yuan, Lei ; Shen, Jianbing

Author_Institution

Dept. of Phys. & Astron., Univ. of Nebraska, Lincoln, NE, USA

Volume

47

Issue

10

fYear

2011

Firstpage

3740

Lastpage

3743

Abstract

We demonstrate a simple low-power, magnetic sensor system suitable for high-sensitivity magnetic-field mapping, based on solid-state magnetic tunnel junction devices with minimum detectable fields in a 100 pT range at room temperature. In this paper, we discuss a method that uses multilayer thin films to improve the performance of the soft ferromagnetic layer in magnetoresistive sensor applications, by reducing the coercivity and/or improving the reversibility. We have used it in the design of our new magnetic sensor. This sensor has a sensitivity as high as 750%/mT. The magnetic sensor only dissipates 1 mW of power while operating under an applied voltage of 1 V.

Keywords

boron alloys; cobalt alloys; coercive force; ferromagnetic materials; iron alloys; magnetic hysteresis; magnetic multilayers; magnetic sensors; magnetic thin films; magnetic tunnelling; magnetisation reversal; magnetoresistive devices; nickel alloys; soft magnetic materials; Fe₂₀Ni₈₀Co₂₀B₂₀; coercivity; dissipation; high-sensitivity magnetic-field mapping; magnetic flux density 100 pT; magnetic hysteresis; magnetoresistive sensor applications; multilayer thin films; picotesla magnetic sensors; power 1 mW; reversibility; soft ferromagnetic layer; solid-state magnetic tunnel junction device; temperature 293 K to 298 K; voltage 1 V; Annealing; Iron; Junctions; Magnetic hysteresis; Magnetic sensors; Magnetic tunneling; Noise; Magnetic concentrators; magnetic noise; magnetic sensor; magnetic tunnel junction (MTJ);

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2011.2157997

Filename

6028053