Magnetically controlled spin light-emitting diode

The fundamental physical principles underlying the operation of basic elements of spintronics are considered, including the giant magnetoresistance effect, injection of spinpolarized charge carriers from a magnetized ferromagnetic contact, and radiative recombination in semiconductors involving spin-polarized carriers.An integrated GaAs-based structure implementing all of the above phenomena, a magnetoresistive spin light-emitting diode, has been fabricated and investigated.As an electrical circuit, the device under consideration is a magnetoresistive element and a metal/tunnel-thin dielectric/semiconductor light-emitting diode connected in series.It is shown that a magnetic field directed in the plane of the layers changes the state of the magnetoresistive element (high or low resistance) and thus allows controlling the intensity of electroluminescence.A magnetic field directed perpendicular to the plane of the layers ensures magnetization of the magnetic contact of the light-emitting diode and spin injection, accompanied by the emission of circularly polarized light.The resulting device can find itself in four stable magnetic states (high-low intensity, `positive'`negative' circular polarization).Such a structure can serve as a basis for magnetic recording and information transmission elements, in which four stable states form quaternary instead of binary logic.