Revisiting the crossover region of the series double QD system using LDECA+DMRG

B.BRAVO, M.E. TORIO, C.J. GAZZA; C.A.BÜSSER; G.B.MARTINS; E.ANDA

Tucumán

Congreso; Solidos 2011; 2011

Competition between ground states in strongly correlated systems have received much attention lately. Specially in mesoscopic systems, which provide a high degree of tunability. In this work we study, using a new technique called LDECA+DMRG [1], the crossover region of a double quan- tum dot (QD) coupled in series (with each QD coupled to an independent lead)[2]. It is known that when the hopping between the QDs is larger than the coupling of each QD to their respective leads, the system is in the so-called molecular regime, in which two Kondo effects occur at different gate voltages. At very low values of inter-dot hopping, two spatially separated Kondo effects occur at the same gate potential (each QD forms a Kondo singlet with its adjacent lead). It is the region of crossover between these two well defined regions that is the main concern of this work. It is expected that this region will display a competition between a singlet coupling both dots and the two independent Kondo effects. Using LDECA+DMRG, we tackle this complicated two-channel problem and unravel the properties related to the competition between Kondo and the interdot singlet.