Giant Magneto Resistance (GMR)

Similar to other magnetoresistive effects, GMR is the change in electrical resistance in response to an applied magnetic field. Transition metals are extensively studies in many applied fields. Their magnetoresistive effects have also received significant interests. It was observed that applying a magnetic field to a Fe/Cr multilayer resulted in a significant decrease in the electrical resistance of the multilayer. This phenomenon, known as “giant magnetoresistance” or GMR, was found to be much more pronounced than ordinary or anisotropic magnetoresistance. A similar, albeit less pronounced effect, was also discovered in Fe/Cr/Fe trilayers. High magnetoresistance values can be achieved in other magnetic multilayers, such as Co/Cu. The change in resistance occurs when the magnetic field aligns the magnetic moments of the consecutive ferromagnetic layers. In the absence of a magnetic field, the magnetizations of the ferromagnetic layers are antiparallel. However, when a magnetic field is applied, the electrical resistance decreases by aligning the magnetic moments and saturating the magnetization of the multilayer.

The GMR device manufactured by MDK enables precise measurements of magnetoresistance changes in the presence of magnetic fields.