Kondo shuttling in a nanoelectromechanical single-electron transistor

We investigate theoretically a mechanically assisted Kondo effect and electric charge shuttling in a nanoelectromechanical single-electron transistor. It is shown that the mechanical motion of the central island (a small metallic particle) with the spin results in a time-dependent tunneling width $\Gamma \left(t\right)$ which leads to an effective increase of the Kondo temperature. The time-dependent oscillating Kondo temperature $T_K\left(t\right)$ changes the scaling behavior of the differential conductance, resulting in the suppression of transport in a strong-coupling and its enhancement in a weak-coupling regime. The conditions for fine-tuning of the Abrikosov-Suhl resonance and possible experimental realization of the Kondo shuttling are discussed.

Figure 1

(Color online) (a) Nanomechanical resonator with an odd number of electrons as a “mobile quantum impurity.” (b) Time evolution of the level spacing for the shuttle with an even number of electrons measured with respect to evolving Kondo temperature. (c) Pulse ZBA in tunneling conduction for Kondo shuttling with the singlet-triplet transition.

Figure 2

(Color online) Differential conductance of a Kondo shuttle ${\Gamma }_0∕U=0.4$. Solid line denotes $G$ for the shuttle ${\Gamma }_L={\Gamma }_R$, $A={\lambda }_0$. Dashed line: the static nanoisland ${\Gamma }_L={\Gamma }_R$, $A=0$. Dotted line: ${\Gamma }_L∕{\Gamma }_R=0.5$, $A=0$. The inset shows the time oscillations of $T_K$ for small $A=0.05{\lambda }_0$ (dotted line) and large $A=2.5{\lambda }_0$ (solid line) shuttling amplitudes.