Spintronics, or spin electronics is the study of electrons and nuclear spin in solid state physics and applications to devices that utilize spin properties instead of or in addition to charge degrees of freedom in an electron. Whereas in electronics information is carried in the charge of an electron, spintronics carries information in the spin of an electron. The spin of an electron is a quantum mechanical property that specifies the electron’s intrinsic angular momentum. An electron has two spin states, spin up and spin down. In spintronics, the spins of electrons can be manipulated by magnetic materials and also by light (photonics).
A read head and memory storage device that uses spintronics is the giant-magnetoresistive (GMR) sandwich structure consisting of alternating ferromagnetic and nonmagnetic metal layers. The device resistance changes (magnetoresistance) depending on the relative orientation of the magnetizations in the magnetic layers. Magnetoresistance is used to sense changes in magnetic fields. Magnetic tunnel junction devices use a tunneling current that depends on the spin orientations of the electrodes.