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arXiv · 1110.5819

Tunable Kondo effect in double quantum dots coupled to ferromagnetic contacts

Rok Žitko·Jong Soo Lim·Rosa Lopez·Jan Martinek·Pascal Simon
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Abstract

We investigate the effects induced by spin polarization in the contacts attached to a serial double quantum dot. The polarization generates effective magnetic fields and suppresses the Kondo effect in each dot. The super-exchange interaction ($J_{\mathrm{AFM}}$), tuned by the inter-dot tunnelling rate $t$, can be used to compensate the effective fields and restore the Kondo resonance when the contact polarizations are aligned. As a consequence, the direction of the spin conductance can be controlled and even reversed using electrostatic gates alone. Furthermore, we study the associated two-impurity Kondo model and show that a ferromagnetic exchange coupling ($J_{\mathrm{FM}}$) leads to an effective spin-1 exchange-anisotropic Kondo model which exhibits a quantum phase transition in the presence of partially polarized contacts.

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Rok Žitko, Jong Soo Lim, Rosa Lopez, Jan Martinek, Pascal Simon. 2011-10-27. Tunable Kondo effect in double quantum dots coupled to ferromagnetic contacts. https://doi.org/10.1103/physrevlett.108.166605

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