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Quantum Phase Transition and Ferromagnetic Spin Correlation in Parallel Double Quantum Dots |
| DING Guo-Hui1;YE Fei2 |
| 1Department of Physics, Shanghai Jiao Tong University, Shanghai 2002402Center for Advanced Study, Tsinghua University, Beijing 100084 |
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| Cite this article: |
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DING Guo-Hui, YE Fei 2007 Chin. Phys. Lett. 24 2926-2929 |
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Abstract We investigate electronic transport through a parallel double quantum dot (DQD) system with strong on-site Coulomb interaction, as well as the interdot tunnelling. By applying numerical renormalization group method, the ground state of the system and the transmission probability at zero temperature are obtained. For a system of quantum dots with degenerate energy levels and
small interdot tunnel coupling, the spin correlations between the DQDs is ferromagnetic, and the ground state of the system is a spin-1 triplet state. The linear conductance will reach the unitary limit (2e2/h) due to the Kondo effect at low temperature. As the interdot tunnel coupling increases, there is a quantum phase transition from ferromagnetic to anti-ferromagnetic spin correlation in DQDs and the linear conductance is strongly suppressed.
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| Keywords:
72.15.Qm
73.21.La
73.40.Gk
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Received: 09 July 2007
Published: 20 September 2007
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