Magnetoresistanssiin

Magnetoresistanssiin is a phenomenon where the electrical resistance of a material changes when it is exposed to an external magnetic field. This effect is observed in various materials, including metals, semiconductors, and magnetic materials. The magnitude and nature of the magnetoresistance depend on the material's properties and the applied magnetic field.

There are several types of magnetoresistance. Ordinary magnetoresistance, observed in non-magnetic metals, typically causes a small increase in resistance with increasing magnetic field. Giant magnetoresistance (GMR) is a more dramatic effect observed in multilayered structures composed of alternating ferromagnetic and non-magnetic layers. In GMR materials, the resistance can change significantly depending on the relative alignment of the magnetic moments in the ferromagnetic layers, which can be controlled by an external magnetic field. Another important type is tunnel magnetoresistance (TMR), which occurs in magnetic tunnel junctions. Here, electrons tunnel through a thin insulating barrier between two ferromagnetic layers. The tunneling probability, and thus the resistance, depends on the relative magnetization of the two layers.

Magnetoresistive effects have found widespread applications. GMR and TMR materials are crucial components in modern hard disk drives, enabling higher data storage densities. They are also used in magnetic sensors for applications like automotive systems, industrial controls, and biomedical devices. Research continues to explore new materials and optimize existing ones to achieve even greater magnetoresistive effects for future technological advancements.