Magnetotransport Effects Of Parallel Double Quantum Dots Embedded In A Mesoscopic Ring

In spintronics, many researchers are interested in the use of spin magnetism and the spin polarization. They are focus on the model of quantum dots which is the carrier of the spin magnetism and the spin polarization. Quantum dot model includes single quantum dot model and multi-quantum dots model. The structure of single quantum dot model is simple and we can easily study it. At present, both in theory and experiment the model of single quantum dot has been studied completely. Compared with single quantum dot model, multi-quantum dots model holds richer physical phenomena and it has much bigger potential applications. Multi-quantum dots model is investigated in its infancy, there are many things worth exploring. In this paper, we have investigated the model of parallel double quantum dots embedded in a mesoscopic ring. The double quantum dots’ left and right ends are connected to ferromagnetic electrodes in order to study the transport properties of the system.There are two states for our system. The symmetry state is that double quantum dots’ energy is equal while the non-symmetry state is that double quantum dots’ energy isn’t equal. In order to explore the transport properties, we consider the Coulomb interaction between the quantum dots and magnetic flux through the system. By theoretical calculation, we have got the following conclusions:(1) In the symmetric state, when the value of the magnetic flux is π/2, the current can be improved significantly for anti-parallel distribution of magnetic structure; but in the non-symmetric state, the magnetic flux can make the negative differential conductance disappear.(2) Both in the symmetric state and non-symmetric state, when the value of magnetic flux is π, the anti-parallel current exceeds the parallel current, so that the negative tunneling magnetoresistance appears.(3) Because of the Coulomb interaction U=0.8, both the currents from a step are split into two steps. If without the Coulomb interaction, the tunneling magnetoresistance goes up because the value of magnetic flux increases. But due to the Coulomb interaction, the tunnel magnetoresistance decreases with the increasing of magnetic flux.(4) The energy inequality of double quantum dots can produce negative differential conductance. By our theoretical study, we have obtained negative tunneling magnetoresistance, huge tunnel magnetoresistance and negative differential conductance under certain conditions. We hope that the new nature is useful for the corresponding experimental researchers. At the same time, we also believe that these results must have some potential in spintronics.