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Author

Peter Groot

Bio: Peter Groot is an academic researcher. The author has contributed to research in topics: Magnetoresistance & Thin film. The author has an hindex of 1, co-authored 1 publications receiving 14 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a contactless angle detector based on the anisotropic magnetoresistance effect (AMR effect) in a permalloy thin film is presented, and the results of high-temperature annealing treatment of the pemalloy film are discussed.
Abstract: An overview is given of the results of our research on a contactless angle detector based on the anisotropic magnetoresistance effect (AMR effect) in a permalloy thin film. The results of high-temperature annealing treatment of the pemalloy film are discussed. Such a treatment suppresses the effects of the uniaxial magnetic anisotropy that is present in a permalloy thin film and increases the AMR effect, thus improving the detector signal. The performance of the detector throughout a temperature range of 20 to 120 °C and the results of heat treatment at 125 °C for 1 week have been tested.

14 citations


Cited by
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Patent
22 Nov 1995
TL;DR: In this paper, the rotational position of a rotatable element without contacting it is determined by comparing the input current to one of the sensors and the sum of the output signals of the respective sensor elements.
Abstract: The apparatus for determining rotational position of a rotatable element without contacting it includes a sensor device having two Hall or AMR sensor elements for sensing a magnetic field of magnetic field strength (B) generated by or influenced by the rotational position of the rotatable element and for producing output signals according to the magnetic field and thus the rotational position of the rotatable element. In order to easily detect the absolute rotational position of the rotatable element, the sensor device is constructed and positioned with respect to the rotatable element so that in every rotational position the field lines from the rotatable element extend at right angles to the sensor structures defined by the direction of an alternating current in the sensor elements. Using different embodiments of an electronic evaluation circuit, the direction components of the magnetic field are evaluated to determine the rotational position by comparing the input current to one of the sensors and the sum of the output signals of the respective sensor elements. Either sinusoidal or rectangular alternating voltages or direct voltages are input to the sensor elements.

108 citations

Patent
02 Oct 2002
TL;DR: In this article, the shape anisotropy energy of giant magnetoresistive elements (GMR elements) is expressed by A*Js*(Br/π) using saturation magnetization Js of a free magnetic layer and remanent magnetic flux density Br, A is set within a range of −350
Abstract: When shape anisotropy energy of giant magnetoresistive elements (GMR elements) is expressed by A*Js*(Br/π) using saturation magnetization Js of a free magnetic layer and remanent magnetic flux density Br, A is set within a range of −350

34 citations

Patent
Klaus Marx1, Franz Jost1
23 Aug 1997
TL;DR: In this paper, a contactless magneto-resistive angle sensing device is presented, where two sensor components (10,11) oriented at a fixed angle relative to each other, a controllable power supply (PW) to heat and maintain the sensor components at different temperatures, a magnet (MG) producing a magnetic field, and an evaluating device (12) to receive output signals (U1,U2) from sensor components, each sensor component is mounted on a rotatable part whose angular position is to be subsequently measured at an angular position in relation to
Abstract: The contactless magneto-resistive angle sensing device (1) includes two sensor components (10,11) oriented at a fixed angle relative to each other, a controllable power supply (PW) to heat and maintain the sensor components (10,11) at different temperatures, a magnet (MG) producing a magnetic field (B) in which the sensor components are arranged and an evaluating device (12) to receive output signals (U1,U2) from the sensor components (10,11). Each sensor component (10,11) includes magneto-resistive resistors (MR) connected in a respective bridge (B1,B2) having input terminals (I1,I1';I2,I2') for supply of current and output terminals (O1,O1';O2,O2') for the output signal (U1,U2). In a rotating magnetic field the evaluating device (12) analyzes the output signals (U1,U2) as a function of field angle and temperature to determine a reference angle at which the output signals of the angle sensing device have a minimum temperature dependence and stores the reference angle as a zero point for subsequent angular measurements. The sensor components are then mounted on a rotatable part whose angular position is to be subsequently measured at an angular position in relation to a stationary magnetic corresponding to the reference angle.

23 citations

Journal ArticleDOI
TL;DR: In this article, an introduction to the theory of the anisotropic magnetoresistance effect in ferromagnetic thin films is given, ending in a treatment of the minimalization of the free energy which is the result of the intrinsic and extrinsic anisotropies of the thin-film structure.
Abstract: An introduction to the theory of the anisotropic magnetoresistance effect in ferromagnetic thin films is given, ending in a treatment of the minimalization of the free energy which is the result of the intrinsic and extrinsic anisotropies of the thin-film structure. The anisotropic magnetoresistance effect in long strips is reviewed. Attention is given to problems like the formation of domains and measures like biasing and linearization. The paper concludes with a description of some applications which are being developed by the authors: (1) an analyser for the stray field of recording heads; (2) a sensitive magnetometer; (3) an accurate absolute angle detector; and (4) an absolute (linear) position detector.

23 citations

Patent
Klaus Marx1, Hartmut Kittel1
26 Jan 2000
TL;DR: In this paper, a method for determining the magnetic field with respect to its intensity and direction at at least one detection location, and using a first arrangement for superimposing an auxiliary magnetic field, known at least in intensity, on the magnetic fields, and a second arrangement for measuring at least the direction of the magnetic forces resulting from the superimposition of the determined magnetic fields and of the auxiliary magnetic fields at the detection location.
Abstract: A device and a method for determining a magnetic field with respect to its intensity and direction at at least one detection location, and uses a first arrangement for superimposing an auxiliary magnetic field, known at least in intensity, on the magnetic field, and a second arrangement for measuring at least the direction of the magnetic field resulting from the superimposition of the magnetic field to be determined and of the auxiliary magnetic field at the detection location. The magnetic field is determined at the detection location in that the resultant magnetic field produced by the magnetic field to be determined and the auxiliary magnetic field is determined with respect to its direction for at least two different auxiliary magnetic fields; and the magnetic field to be determined is calculated therefrom. The method is especially suited for determining the intensity and direction of a magnetic field in the immediate vicinity of the surface of a magnet.

15 citations