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Tunable Kondo effect in a double quantum dot coupled to ferromagnetic contacts
Rok Žitko1, Jong Soo Lim, Rosa López
1Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
Physical Review Letters
|June 12, 2012
Summary
We demonstrate controlling spin conductance in quantum dots using ferromagnetic contacts. By tuning interactions, we can reverse spin direction, offering new possibilities for spintronic devices.
Area of Science:
- Condensed matter physics
- Quantum electronics
- Materials science
Background:
- Ferromagnetic contacts on quantum dots induce spin polarization, creating effective magnetic fields.
- This spin polarization can suppress the Kondo effect, a key phenomenon in quantum transport.
Purpose of the Study:
- To investigate the impact of ferromagnetic contacts on a serial double quantum dot system.
- To explore methods for controlling spin-dependent transport and the Kondo effect.
Main Methods:
- Theoretical investigation of spin polarization effects in a serial double quantum dot.
- Analysis of superexchange interaction (J(AFM)) tuned by interdot tunneling rate (t).
- Utilizing electrostatic gates to manipulate spin conductance.
Main Results:
- Spin polarization from ferromagnetic contacts suppresses the Kondo effect.
- Superexchange interaction can compensate for effective magnetic fields, restoring the Kondo resonance.
- Spin conductance direction is controllable and reversible using electrostatic gates.
Conclusions:
- Ferromagnetic contacts offer a tunable platform for controlling spin transport in quantum dots.
- Electrostatic gate control provides a novel method for manipulating spin direction in spintronic devices.
- This research advances the development of carbon nanotube-based spintronic devices.
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