Articles you may be interested inQuantum transport through the system of parallel quantum dots with Majorana bound states J. Appl. Phys. 115, 083706 (2014) (2011)], an isolated Majorana state bound to one edge of a long enough Kitaev chain in the topological phase and connected to a quantum dot, results in a robust transmittance of 1/2 at zero-bias. In this work, we show that the removal of such a hallmark can be achieved by using a metallic surface hosting two adatoms in a scenario where there is a lack of symmetry in the Fano effect, which is feasible by coupling the Kitaev chain to one of these adatoms. Thus in order to detect this feature experimentally, one should apply the following two-stage procedure: (i) first, attached to the adatoms, one has to lock AFM tips in opposite gate voltages (symmetric detuning of the levels De) and measure by an STM tip, the zero-bias conductance; (ii) thereafter, the measurement of the conductance is repeated with the gates swapped. For jDej away from the Fermi energy and in the case of strong coupling tip-host, this approach reveals in the transmittance, a persistent dip placed at zero-bias and immune to the aforementioned permutation, but characterized by an amplitude that fluctuates slightly around 1/2. However, in the case of a tip acting as a probe, the adatom decoupled from the Kitaev chain becomes completely inert and no fluctuation is observed. Therefore, the STM tip must be considered in the same footing as the "hostþadatoms" system. As a result, we have found that despite the small difference between these two Majorana dips, the zero-bias transmittance as a function of the symmetric detuning yields two distinct behaviors, in which one of them is unpredictable by the standard Fano's theory. Therefore, to access such a non trivial pattern of Fano interference, the hypothesis of the STM tip acting as a probe should be discarded. V C 2014 AIP Publishing LLC.

We study the transport properties of a hybrid nanostructure composed of a ferromagnet, two quantum dots, and a superconductor connected in series. By using the nonequilibrium Green's function approach, we have calculated the electric current, the differential conductance, and the transmittance for energies within the superconductor gap. In this regime, the mechanism of charge transmission is the Andreev reflection, which allows for a control of the current through the ferromagnet polarization. We have also included interdot and intradot interactions, and have analyzed their influence through a mean-field approximation. In the presence of interactions, Coulomb blockade tend to localize the electrons at the double-dot system, leading to an asymmetric pattern for the density of states at the dots, and thus reducing the transmission probability through the device. In particular, for nonzero polarization, the intradot interaction splits the spin degeneracy, reducing the maximum value of the current due to different spin-up and spin-down densities of states. Negative differential conductance appears for some regions of the voltage bias, as a result of the interplay of the Andreev scattering with electronic correlations. By applying a gate voltage at the dots, one can tune the effect, changing the voltage region where this novel phenomenon appears. This mechanism to control the current may be of importance in technological applications.

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