Full electrostatic control over polarized currents through spin-orbital Kondo effect

Abstract

Numerical calculations indicate that by suitably controlling the individual gate voltages of a capacitively coupled parallel double quantum dot, with each quantum dot coupled to one of two independent non-magnetic channels, this system can be set into a spin-orbital Kondo state by applying a magnetic field. This Kondo regime, closely related to the SU(4) Kondo, flips spin from one to zero through cotunneling processes that generate almost totally spin-polarized currents with opposite spin orientation along the two channels. Moreover, by appropriately changing the gate voltages of both quantum dots, one can simultaneously flip the spin polarization of the currents in each channel. As a similar zero magnetic field Kondo effect has been recently observed by Y. Okazaki {\it et al.} [Phys. Rev. B {\bf 84}, (R)161305 (2011)], we analyze a range of magnetic field values where this polarization effect seems robust, suggesting that the setup may be used as an efficient bipolar spin filter, which can generate electrostatically reversible spatially separated spin currents with opposite polarizations.

6 pages, 8 figures (including supplemental material)

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• Observation of the SU(4) Kondo state in a double quantum dot
• Pseudospin-Resolved Transport Spectroscopy of the Kondo Effect in a Double Quantum Dot
• Orbital Kondo spectroscopy in a double quantum dot system
• Nonequilibrium self-energies, Ng approach and heat current of a nanodevice for small bias voltage and temperature
• Conditions for observing emergent SU(4) symmetry in a double quantum dot
• Restoring the SU(4) Kondo regime in a double quantum dot system
• Polarized currents and spatial separation of Kondo state: NRG study of spin-orbital effect in a double QD
• Manipulability of the Kondo effect in a T-shaped triple-quantum-dot structure
• The $SU(4)-SU(2)$ crossover and spin filter properties of a double quantum dot nanosystem
• Width of the charge-transfer peak in the SU(N) impurity Anderson model and its relevance to non-equilibrium transport
• Two-stage three-channel Kondo physics for an FePc molecule on the Au(111) surface
• Orbital Kondo effect in a parallel double quantum dot
• SU(4) Kondo entanglement in double quantum dot devices
• Suppressed Josephson phase transition in one parallel double-quantum-dot junction
• The graphene sheet versus the 2DEG: a relativistic Fano spin-filter via STM and AFM tips
• Electron-phonon interaction and electronic correlations in transport through electrostatically and tunnel coupled quantum dots
• Spin orbit interaction in nanotubes