Adiabatic Pumping in the Mixed-Valence and Kondo Regimes

We investigate adiabatic pumping through a quantum dot with a single level in the mixed-valence and Kondo regimes using the slave boson mean field approximation. The pumped current is driven by a gauge potential due to time-dependent tunneling barriers as well as by the modulation of the Friedel phase. The sign of the former contribution depends on the strength of the Coulomb interaction. Under finite magnetic fields, the separation of the spin and charge currents peculiar to the Kondo effect occurs.

Figure 1

Pumping paths in the ($\theta$, $V_g$) plane. $V_3$ is defined through a relation for $\delta$: $\delta (V_3)=[\delta (V_2)+\delta (V_1)]/2$.

Figure 2

Pumped charge $Q$ (in the unit of $e/2\pi$) for the path in Fig. 1a as a function of $V_2$ for $V_1=\Gamma$. The solid and dashed lines stand for the interacting ($u\to \infty$) and noninteracting ($u=0$) models, respectively.

Figure 3

Electron pumping under the Zeeman effect; $E_Z=0.5\times {10}^{-3}\Gamma$. (a) ${\delta }_{\sigma }$ as a function of the gate voltage $V_g$. (b) The pumped charge (spin) $Q_{c/s}=Q_{+}\pm Q_{-}$ [dashed (solid) line], (in the unit of $e/2\pi$) for the path in Fig. 1c as a function of $V_1$ for $V_2=-2.0\Gamma$.

Figure 4

(a) A pumping path in the ($\theta ,V_g$) plane. (b) The amplitude of the charge (spin) alternating current, $A_{c/s}=A_{+}\pm A_{-}$ [dashed (solid) line] as a function of $V_1$.