Emergence of a negative charging energy in a metallic dot capacitively coupled to a superconducting island

Cecilia Holmqvist (1) , Denis Feinberg (2) , Alex Zazunov (3)

1 Applied Quantum Physics Laboratory, MC2
2 NEEL - ThQC - Théorie Quantique des Circuits
3 LPM2C - Laboratoire de physique et modélisation des milieux condensés

We consider the hybrid setup formed by a metallic dot, capacitively coupled to a superconducting island S connected to a bulk superconductor by a Josephson junction. Charge fluctuations in S act as a dynamical gate and overscreen the electronic repulsion in the metallic dot, producing an attractive interaction between two additional electrons. As the offset charge of the metallic dot is increased, the dot charging curve shows positive steps ($+2e$) followed by negative ones ($-e$) signaling the occurrence of a negative differential capacitance. A proposal for experimental detection is given, and potential applications in nanoelectronics are mentioned.

Mots clés: nanostructures; superconductivity; Coulomb blockade

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Cecilia Holmqvist, Denis Feinberg, Alex Zazunov. Emergence of a negative charging energy in a metallic dot capacitively coupled to a superconducting island. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2008, 77 (5), pp.054517. ⟨10.1103/PhysRevB.77.054517⟩. ⟨hal-00136840v5⟩