Ultrafast optical orientation and coherent Larmor precession of electron and hole spins in bulk germanium

Circularly polarized light is demonstrated to inject partially spin-polarized electrons and holes in bulk germanium via both direct and indirect optical transitions. While the degree of spin polarization is markedly reduced when compared to prototypical III-V semiconductors, coherent spin precessions in an external magnetic field are well resolved in ultrafast magneto-optics. At cryogenic temperatures, hole (electron) spins exhibit remarkably long coherence times of $~100$ ps ($~1$ ns).