Spin-LED enable almost purely circularly polarized emission

Researchers from the Tokyo Institute of Technology managed to achieve an almost purely circularly polarized (CP) electroluminescence (EL) in spin-polarized LEDs at room temperature without an external magnetic field.

The researchers used LEDs and a polycrystalline Fe in-plane spin injector. During the experiment the researchers injected spins of a given type, which were dispersed due to spin relaxation. Radiative recombination subsequently occurred, which was observed in the form of a linearly polarized emission. Almost pure circularly polarized emission was achieved when the current density was high enough.

The researchers say that they still need to understand the mechanism behind these nonlinear processes. Potential applications for these Spin-LEDs exist in secure optical communications, cancer diagnosis, and optically enhanced nuclei imaging.

In 2012 researchers from the University of Utah and the Israeli Technion developed a new kind of Spintronics OLED device known as a spin-polarized OLED, that can be brighter than regular OLEDs.