Gmr magnetic field sensor is a giant magnetoresistive magnetic field sensor. It is a high-tech product integrating magnetic thin film, semiconductor integration and nanotechnology, and is widely used. Its technical structure applies a mathematical formula: gmr sensor = magnetic material+nanotechnology+semiconductor integration.

Giant Magnetoresistance (GMR) sensor connects four GMR structures into a bridge, and then magnetically shields two of them to make them insensitive to magnetic field. When there is an external magnetic field, the resistances of the two unshielded GMR structures change under the action of the magnetic field, and the output of the bridge changes under the excitation of an external constant voltage source or a constant current source, thus achieving the purpose of measuring the external magnetic field.

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Brief introduction of giant magnetoresistance effect

The 2007 Nobel Prize in Physics was awarded to Peter Peter Gruenberg of Helmholtz Research Center in ulich and Professor Albert Fett of XI University. In 1980s, the two winners independently conducted research on giant magnetoresistance (gmr).

Both of them won this year's Nobel Prize in physics for discovering the giant magnetoresistance effect. The external magnetic field can greatly change the resistance of the magnetic material thin layer through the giant magnetoresistance effect. The discovery of gmr effect paves the way for the development of a new read head for compact computer hard disks, which can increase the storage capacity of hard disks of personal computers, portable music players (mp3 players) and cameras to several gigabytes.

Gmr effect is caused by the change of resistance caused by the magnetic field of multilayer metal films with a thickness of several nanometers. Simply put, the metal film consists of a reference layer whose magnetization direction (reference direction) is fixed and stable and a sensing layer whose magnetization direction is determined by an external magnetic field (such as a compass).

The sensing layer and the reference layer are separated by a copper layer which is only a few atoms thick, thus generating the gmr effect. The angle between the applied magnetic field and the sensor reference layer determines the resistance change of the metal film.

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