I became fascinated with spintronics for about a year. Somewhat unrelated, but perhaps interesting to some readers, is that you can create spin-LEDs. If you use a material to permit only electrons of a certain spin (spin-up or spin-down) to transport to the excitation layer of the LED, the resultant emitted photons will be helically polarized. Fascinating stuff.

Interesting, is that what is used for stereoscopic video screens?

Good question, but I'm 99.9999% sure no. They may us Circularly Polarized light (I actually don't know), but if they do it's made by filtration of unpolarized light rather than polarized electroluminescence. When I was researching the topic (~2008-ish), Spin-LEDs were largely still in the lab - a lot of work at Stanford spintronics lab as I recall. At that time, they were able to achieve a strong bias of circularly polarized light. I just googled it and apparently there's beed good progress in 'purifying' the polarization handedness [1]. If you can harness CP emission, it opens the door for many very interesting applications. CP light is fascinating.

1. https://www.spiedigitallibrary.org/conference-proceedings-of...

Very cool, thanks for answer and the paper link!

> if, in use, its thickness approaches the wavelength of your charge carrier

Tangentially, a conceptually similar and equally counterintuitive phenomenon is attenuated total reflection. (https://en.wikipedia.org/wiki/Attenuated_total_reflectance)

Fascinating.

I had only just learned about "evanescent wave" interactions. The idea is that, alongside wave propagation, E-M mechanics admits numerous non-wave, and therefore short-range solutions. These solutions are necessary to explain total internal reflection. E-M interactions with materials a short distance beyond the boundary can change the reflectance. ATR is clever in using multiple such interactions to sample properties of a material close enough to the boundary.