Magnetoresistive sensor having at least a layer system and a plurality of measuring contacts disposed thereon, and a method of producing the sensor
AssigneeSiemens Aktiengesellschaft
InventorHugo van den Berg
Life of this patent
Estimating the term…
Abstract
A magnetoresistive sensor includes at least one measuring layer having a magnetization M.sub.M in the plane of the layer, and a bias layer having a fixed magnetization M.sub.B in the plane of the layer, which are exchange-decoupled from one another by an interlayer. To achieve magnetostatic decoupling of the measuring layer and the bias layer coupled anti-ferromagnetically in an "artificial anti-ferromagnet" to a magnetic layer through a coupling layer. In a preferred embodiment, the magnetizations of the measuring layer M.sub.M and of the bias layer M.sub.B are at least approximately orthogonal to each other. The resulting sensor has a linear characteristic and maximum sensitivity.
Claims22
A magnetoresistive sensor comprising:
- a) a layer system, wherein said layer system includes:
- a1) at least one measuring layer which, in the plane of said measuring layer, has a magnetization which at least in one direction depends reversibly on an applied magnetic field, and in the absence of said magnetic field, said magnetization corresponds to a predefined ground state magnetization;
- a2) at least on one side of the measuring layer a bias layer having a magnetization in the plane of said bias layer, said magnetization being at least approximately constant in the measuring range of the magnetic field;
- a3) an interlayer, disposed between the bias layer and the measuring layer, by which interlayer the bias layer is at least approximately magnetically exchange-decoupled from the measuring layer;
- and
- a4) a magnetic layer which is coupled anti-ferromagnetically to the bias layer through a coupling layer, said coupling layer being disposed between the bias layer and the anti-ferromagnetically coupled magnetic layer;
- and
- b) measuring contacts at the layer system to detect a resistance signal which is a measure for the applied magnetic field.
A method for fabricating a magnetoresistive sensor having a multilayer structure including a measuring layer, a bias layer, an interlayer between said measuring layer and bias layer, a magnetic layer and a coupling layer between the bias layer and the magnetic layer, comprising the following steps:
- a) selecting magnetic materials for the bias layer and the magnetic layer having different Curie temperatures and at least approximately equal magnetizations at a given operating temperature and different magnetizabilities at a magnetizing temperature that differs from the operating temperature;
- b) bonding together the bias layer, the coupling layer, and the magnetic layer by:
- i) bringing the bias layer in contact with one side of the coupling layer, and bringing the magnetic layer in contact with the other side of the coupling layer;
- ii) bringing the assembly of step i) to the magnetizing temperature;
- and
- iii) arranging said assembly in a temperature-dependent biasing magnetic field which has a predetermined value at least at said magnetizing temperature;
- c) bringing said assembly to the operating temperature.
Dependencies are inferred from the claim text.