Quantum phase transition and Coulomb blockade effect in triangular quantum dots with interdot capacitive and tunnel couplings

Abstract

The quantum phase transition and the electronic transport in a triangular quantum dot system are investigated using the numerical renormalization group method. We concentrate on the interplay between the interdot capacitive coupling V and the interdot tunnel coupling t. For small t, three dots form a local spin doublet. As t increases, due to the competition between V and t, there exist two first-order transitions with phase sequence spin-doublet-magnetic frustration phase-orbital spin singlet. When t is absent, the evolutions of the total charge on the dots and the linear conductance are of the typical Coulomb-blockade features with increasing gate voltage. While for sufficient t, the antiferromagnetic spin correlation between dots is enhanced, and the conductance is strongly suppressed for the bonding state is almost doubly occupied.

Voltage-controlled Kosterlitz–Thouless transitions and various kinds of Kondo behaviors in a triple dot device

“…[16][17][18][19][20] Furthermore, TQD systems are also considered as ideal models to show the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, [21,22] the quantum interference, [23][24][25][26] and various kinds of quantum phase transition (QPT). [13,15,[27][28][29][30][31][32] Basically, these behaviors depend closely on the organizations of the quantum dots and the conduction leads, as well as the coupling/interaction elements which have been taken into account.…”