Abstract
The exchange field for molecular states of double quantum dot, induced by two ferromagnets coupled to the device in T-shaped configuration, is defined and calculated. It is found, that in the regime of strong coupling between quantum dots, the dependence of the exchange field on this coupling becomes nontrivial. In particular, it changes the sign a few times to eventually vanish in the limit of infinite inter-dot coupling. The excitation energies of double quantum dot are calculated and the results used to predict the conditions for suppression of the two-stage Kondo effect in the considered nanostructure.
Highlights
When a discrete level is coupled to a large system of continuous energy spectrum, it is broadened, and shifted [1]
Denoting by |e∗i the state of the system, in which double quantum dots (DQDs) is in the state |ei and the effective ferromagnetic electrodes (Fs) is in its ground state, one can write the zero-temperature expression for the shift of the energy level Ei in the second order in HI, δEi =
Setting t = 0 and U2 = ε2 = 0, one practically obtains a single quantum dot (QD) coupled to the ferromagnet, plus a free orbital of zero energy
Summary
When a discrete level is coupled to a large system of continuous energy spectrum, it is broadened, and shifted [1]. In the present paper a similar system with ferromagnetic electrodes (Fs) is considered (see Fig. 1) It is shown, by means of perturbative calculation, that the exchange field can be considered as an alternative mechanism of breaking the singlet and restoring the Kondo effect. By means of perturbative calculation, that the exchange field can be considered as an alternative mechanism of breaking the singlet and restoring the Kondo effect This is confirmed by numerical renormalization group calculations [18].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
