The two-terminal magneto-conductance of a hole gas in C-doped AlGaAs/GaAs heterostructures with ohmic contacts consisting of alloyed In/Zn/Au displays a pronounced hysteresis of the conductance around zero magnetic field. The hysteresis disappears ab
ove magnetic fields of around 0.5 T and temperatures above 300 mK. For magnetic fields below 10 mT we observe a pronounced dip in the magneto-conductance. We tentatively discuss these experimental observations in the light of superconductivity of the ohmic contacts.
Strong spin-orbit interaction characteristic for p-type GaAs systems, makes such systems promising for the realization of spintronic devices. Here we report on transport measurements in nanostructures fabricated on p-type, C-doped GaAs heterostructur
es by scanning probe oxidation lithography. We observe conductance quantization in a quantum point contact, as well as pronounced Coulomb resonances in two quantum dots with different geometries. Charging energies for both dots, extracted from Coulomb diamond measurements are in agreement with the lithographic dimensions of the dots. The absence of excited states in Coulomb diamond measurements indicates that the dots are in the multi-level transport regime.
