The phenomena of spin-filter tunnelling

The spin filtering phenomenon allows one to obtain highly spin-polarized charge carriers generated from nonmagnetic electrodes using magnetic tunnel barriers. The exponential dependence of tunnel current on the tunnel barrier height is operative here. The magnetic, semiconducting europium chalcogenide compounds have strikingly demonstrated this effect. The possibility of employing ferrites and other methods opens the potential for display of this phenomenon at room temperature, which can be expected to lead to huge progress in spin injection and detection in semiconductors. But first, extremely challenging material-related issues have to be addressed. This review covers the field.