Title: An accurate model of a highly ordered 81/19 Permalloy AMR Wheatstone bridge sensor against a 48 pole pair ring-magnet

Authors: Michael J. Haji-Sheikh, Young Yoo

Addresses: Department of Electrical Engineering, Northern Illinois University, De Kalb, IL 60115, USA. ' Department of Physics, Northern Illinois University, De Kalb, IL 60115, USA

Abstract: Presented is a method to model a magnetoresistive Wheatstone bridge using a new magnetoresistive model for resistor elements in saturation. The model works well with highly ordered thin films such as Permalloy. This new model accurately predicts the behaviour of individual magnetoresistors and follows the form ΔR/R0 = A + B((1 + C × cos(2θ)²) + C × sin(2θ)²)1/2. To demonstrate the use of this model, a 17.5 nm thick Permalloy sensor bridge was used to sense a 48 pole pair ring-magnet. The results show a good correlation between the model and an actual device under test.

Keywords: Permalloy; anisotropic magnetoresistive; AMR Wheatstone bridge sensors; saturation; ring magnets; modelling; magnetoresistors; thin films.

DOI: 10.1504/IJISTA.2007.014129

International Journal of Intelligent Systems Technologies and Applications, 2007 Vol.3 No.1/2, pp.95 - 105

Available online: 22 Jun 2007

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