Editing Faraday effect (section)

=== Semiconductors ===
[[File:GaAs-Faraday rotation spectrum.png|thumb|upright=1.25|GaAs-Faraday rotation spectrum]]
Due to spin-orbit coupling, undoped [[GaAs]] single crystal exhibits much larger Faraday rotation than glass (SiO<sub>2</sub>). Considering the atomic arrangement is different along the (100) and (110) plane, one might think the Faraday rotation is polarization dependent. However, experimental work revealed an immeasurable anisotropy in the wavelength range from 880–1,600&nbsp;nm. Based on the large Faraday rotation, one might be able to use GaAs to calibrate the B field of the terahertz electromagnetic wave which requires very fast response time. Around the band gap, the Faraday effect shows resonance behavior.<ref>{{cite journal|last1=G. X.|first1=Du|title=Fast Magneto-optical Spectrometry by Spectrometer|journal=Review of Scientific Instruments|volume=83|issue=1|pages=013103–013103–5|doi=10.1063/1.3673638|pmid=22299925|year=2012|bibcode=2012RScI...83a3103D}}</ref>

More generally, (ferromagnetic) semiconductors return both [[electro-gyration]] and a Faraday response in the high frequency domain. The combination of the two is described by [[gyroelectromagnetic media]],<ref name="Prati2003" /> for which gyroelectricity and gyromagnetism (Faraday effect) may occur at the same time.