Effect Of The Antiferromagnetic Spin Coupling And Interdot Coulomb Repulsion On Kondo Effects In Serial Double Quantum Dots

In recent years, as a new extensive studied topic, mesoscopic quantum transportsystem has attracted much attention because of the rapid development ofsemiconductor devices in physics. We theoretically study the effects of theantiferromagnetic spin coupling and the interdot Coulomb repulsion on Kondoeffects in the serial double quantum dots by means of slave-boson mean-fieldapproximation. Our results indicate that when the quantum dots system is in theweak coupling regime, the antiferromagnetic spin coupling strengthens the Kondoresonance, while the interdot Coulomb repulsion suppresses them for the equilibriumcase， which makes the Kondo resonance peaks reduced. When the system is in thestrong coupling regime, with the antiferromagnetic spin coupling increases, the twodots are coupled coherently and form an artificial molecule and the energy levels ofthe bonding ang antibonding states split clearly. in the Kondo regime. However,whenJ2.5T0Kthe split Kondo peaks increases and the electron tunneling orbit hasbroaden, which makes the electron tunneling orbit broaden and more easily throughthe double quantum dots. Meanwhile, the Coulomb repulsion between the two dotsnot only makes the energy of the bonding and antibonding states increases but alsomakes the charge fluctuations and lead to the orbit resonance. On the other hands,whenJ2.5T0K, the Kondo resonance peaks skip obviously and the density ofelectron increases. In addition, we discussed the development of the density of statesby changed the bias voltage and get some interesting properties when theantiferromagnetic spin coupling and the interdot Coulomb repulsion have been identified. These properties not only provide the basic theory evidence butalsoprovide the guide to study the electron correlation and the through tunnelingproperties in double quantum dots.