Spin-dependent phenomena in digital-magnetic heterostructures: Clustering and phase-space filling effects

Digital-magnetic heterostructures (DMH’s), II-VI quantum wells with “planes” of Mn, exhibit strongly spin-dependent physics. We investigate the magnetic-field $\mathrm{}\left(B\right)\mathrm{}$ dependence of exchange-induced energy splittings and spin-flip scattering in DMH’s. We find that Mn clustering is relevant to explain the magnitude and the concentration dependence of recently observed splittings. Our calculated electron spin-flip times show “branching,” i.e., ${\tau }_{\mathrm{sf}}^{u\overrightarrow{p}\mathrm{down}}$ decreases and ${\tau }_{\mathrm{sf}}^{\mathrm{dow}\overrightarrow{n}\mathrm{up}}$ increases with increasing $B$. This feature, consistent with recent data, is due to the B-field dependence of the available phase space.