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Development of a rotation sensor based on anisotropic magnetoresistance effect

M. VOLMER1,* , M. AVRAM2, J. NEAMTU3

Affiliation

  1. Physics Department, Transilvania University, 29 Eroilor, Brasov 500036, Romania
  2. National Institute for Research and Development in Microtechnologies, Str. Erou Iancu Nicolae 32B, 72996 Bucharest, Romania
  3. Advanced Research Institute for Electrical Engineering, Splaiul Unirii 313, Bucharest, 030138, Romania

Abstract

We present here a method to increase the response quality of a rotation sensor based on the anisotropic magnetoresistance effect (AMR). The sensor is made by deposition of thin layers of Ni80Fe20 (Permalloy) or Ni80Fe20/NM/Ni80Fe20 structures. NM denotes Cu or Al2O3 layers. We used a circular shape deposition mask with approximately 5 mm in diameter. Using a Hall effect geometry we get direct access to the anisotropic part of the resistance with the advantage of a reduced thermal drift of the output signal. Because of the contacts misalignments and hysteresis effects in field dependence of the electrical resistance, the angular behaviour of the Planar Hall effect (PHE) voltage presents some distortions. Making PHE measurements for Permalloy and multilayers (ML) structures over two orthogonal directions for each angle, we obtained, by summating the results, a very symmetrical signal with two periods for a complete rotation in magnetic field. The behaviour of these sensors in rotating magnetic fields was simulated using a micromagnetic simulator. The structures were used for microcompass and contactless potentiometer applications. The measurement system is computer controlled..

Keywords

Thin films, Planar Hall effect, Micromagnetic simulation, Rotation sensor, Anisotropic magnetoresistance effect.

Submitted at: Nov. 2, 2006
Accepted at: April 15, 2007

Citation

M. VOLMER, M. AVRAM, J. NEAMTU, Development of a rotation sensor based on anisotropic magnetoresistance effect, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 4, pp. 1048-1051 (2007)