Abstract

To probe spin injection into different electronic states of doped semiconductors the optical pump-probe technique is used. Optical fsec pulses create spin packets whose coherent precession and dephasing in a transverse magnetic field is detected by time-resolved magnetooptics. The spin lifetimes of electronic states in n-GaAs are longest for delocalized donor band (DB) states, whereas localized DB states yield shortest lifetimes due to interaction with the nuclear spins.

Recently we could demonstrate that short electrical pulses injected from an Fe layer into n-GaAs can yield phase-controlled coherent spin packets. Their magnetooptically detected spin dephasing time amounts to 20 ns. This technique opens also the door to coherent spin transport in Si- and C-based materials.