Magnetoresistiviilmiö

Magnetoresistivity refers to the property of a material to change its electrical resistance in the presence of an external magnetic field. This phenomenon is a fundamental concept in condensed matter physics and has led to the development of various sensor technologies. The magnitude of the magnetoresistive effect can vary significantly between different materials.

There are several types of magnetoresistive effects. Anisotropic magnetoresistance (AMR) is observed in ferromagnetic materials where the resistance depends on the angle between the current and the magnetization direction. Giant magnetoresistance (GMR) is a quantum mechanical effect observed in multilayers of alternating ferromagnetic and non-magnetic conductive layers. When the magnetization of adjacent ferromagnetic layers is parallel, the resistance is low; when it is antiparallel, the resistance is high. Tunnel magnetoresistance (TMR) is similar to GMR but involves electron tunneling through a thin insulating barrier between ferromagnetic layers. TMR effects are typically larger than GMR effects.

The discovery of GMR in 1988 by Albert Fert and Peter Grünberg, who shared the Nobel Prize in Physics in 2007 for this work, revolutionized magnetic sensing. Magnetoresistive sensors are used in a wide range of applications, including hard disk drives for reading data, magnetic field sensors, automotive sensors, and non-volatile magnetic random-access memory (MRAM). The sensitivity and miniaturization capabilities of these sensors continue to drive innovation in many technological fields.