Kondo effect and tristability in a double-quantum dot

Electron tunneling through a non-equilibrium double quantum dot in a series in the Kondo regime is studied. In the region of negative differential resistance, it is shown that this system possesses a complex response to the applied potential characterized by a tristable solution for the current. The different natures of the solutions are characterized and it is shown that the effects of an applied magnetic field could be used to control the region of tristability. The mean-field slave-boson formalism is used to obtain the solution of the problem.