Spin-polarized current in semimagnetic semiconductor heterostructures

A semimagnetic semiconductor tunneling device is proposed as a spin filter. This device, which gives spin-polarized electron current, is obtained by choosing different layers of II-VI compounds, with magnetic moments of substitutional ions of ${\mathrm{Mn}}^{\mathrm{2+}}$ in some of the layers. We present a theoretical calculation of the tunneling current for the device, in which electron spin-flip scattering produced by the thermal fluctuations of the magnetic moments is accounted for and found to be inefficient in depolarizing the current. A different system is also investigated to show more clearly the effects of spin-flip scattering on the tunneling current.