Coulomb-coupled concentric quantum rings

We present measurements done on a novel device consisting of two concentric quantum rings realized by local anodic oxidation in a GaAs/AlGaAs heterostructure. The outer ring is connected to external leads while the inner ring is only Coulomb-coupled to the rest of the system. We studied the electronic transport through the outer ring in dependence of an external magnetic field and found a superposition of oscillations with two distinct Aharonov–Bohm periods in the signal. These matched the diameters of the outer and inner ring respectively, demonstrating an influence of the inner ring on the conductance of the outer one. We attribute this influence to charge redistributions in the inner ring induced by the magnetic field.