Coherent control of an optically-injected ballistic spin-polarized current in bulk GaAs

Summary form only given. One of the major hurdles in the development of spintronic devices has been the problem of injecting spin-polarized currents into a semiconductor. It has been known since the 1970s that spin-polarized carrier populations can be optically injected into semiconductors using a single color, circularly polarized excitation beam. However, without an external bias, no current is generated. On the other hand, Hache et al. (1998) have demonstrated that it is possible to optically inject a ballistic electrical current in an unbiased bulk semiconductor through the quantum interference control (QUIC) of singleand two-photon absorption. However, this electrical current was not spin-polarized. Here, we demonstrate that it is possible to optically inject a spin-polarized ballistic current in an unbiased semiconductor by a judicious choice of incident polarizations and to coherently control the direction of that current by adjusting the phase of the incident light.