Improving Magnetic Field Detection Limits of Spin Valve Sensors Using Magnetic Flux Guide Concentrators

Author

Guedes, A. ; Almeida, J.M. ; Cardoso, S. ; Ferreira, R. ; Freitas, P.P.

Author_Institution

lInstituto Nacional de Engenharia de Sistemas a Computadores-Microsistemas a Nanotecuologias, Lisbon

Volume

43

Issue

6

fYear

2007

fDate

6/1/2007 12:00:00 AM

Firstpage

2376

Lastpage

2378

Abstract

The magnetic field detection limit of spin valve sensors in the thermal noise regime is improved from 1.3 nT/Hz^1/2 to 0.064 nT/Hz^1/2 by incorporating a Co₉₃Zr₃Nb ₄ soft magnetic flux guide concentrator structure. Linear spin valve sensors were processed down to 20times2 mum² dimensions, with and without an additional 3500-Aring-thick flux guide concentrator, with a magnetic flux gain factor ranging from 5 to 20. Spin valves show a starting sensitivity of 0.2 %/Oe, improved to 3.8 %/Oe with the flux concentrator. Noise measurements from dc to 500 kHz were performed, indicating similar noise levels with and without flux concentrators. In terms of magnetic field detection, sensors with flux concentrators show a detection limit of 2 nT/Hz^1/2 at 10 Hz, compared to 47 nT/Hz^1/2 without flux concentrators. No additional 1/f noise is measured in the spin valve sensor response upon the addition of the soft magnetic flux concentrators in the frequency range studied

Keywords

cobalt alloys; magnetic field measurement; magnetic sensors; niobium alloys; soft magnetic materials; spin valves; thermal noise; zirconium alloys; Co₉₃Zr₃Nb₄; linear spin valve sensors; magnetic field detection; magnetic flux gain factor; soft magnetic flux guide concentrators; thermal noise; Gas detectors; Magnetic field measurement; Magnetic flux; Magnetic noise; Magnetic sensors; Niobium; Noise measurement; Spin valves; Thermal sensors; Zirconium; 1/f noise; flux concentrator; low field detection; magnetoresistive sensors; spin valve sensitivity;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2007.893119

Filename

4202744