Title :
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
fDate :
6/1/2007 12:00:00 AM
Abstract :
The magnetic field detection limit of spin valve sensors in the thermal noise regime is improved from 1.3 nT/Hz1/2 to 0.064 nT/Hz1/2 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/Hz1/2 at 10 Hz, compared to 47 nT/Hz1/2 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;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.893119
