Strong spin-orbit interactions and weak antilocalization in carbon-doped p-type GaAs∕Al_xGa_1−xAs heterostructures

We present a comprehensive study of the low-field magnetoresistance in carbon-doped p-type GaAs∕AlGaAs heterostructures aiming at the investigation of spin-orbit interaction effects. The following signatures of exceptionally strong spin-orbit interactions are simultaneously observed: a beating in the Shubnikov–de Haas oscillations, a classical positive magnetoresistance due to the presence of the two spin-split subbands, and a weak antilocalization dip in the magnetoresistance. The spin-orbit-induced splitting of the heavy hole subband at the Fermi level is determined to be around 30% of the total Fermi energy. The phase-coherence length of holes of around 2.5 μm at a temperature of 70 mK, extracted from weak antilocalization measurements, is promising for the fabrication of phase-coherent p-type nanodevices.