Enhancement of charge and spin Seebeck effect in triple quantum dots coupling to ferromagnetic and superconducting electrodes

Superior thermoelectric properties through triangular triple quantum dots (TTQD) attached to one metallic and one superconducting lead

“…In recent years, increasing attention has been paid to multiple QD hybrid systems in different coupling regimes, due to their potential applications in highly efficient nano-electronic devices and fundamental physics research. [18][19][20][21][22][23][24][25][26][27][28][29] The most common examples are double quantum dot (DQD) and triple quantum dot (TQD) systems, they not only have superior thermoelectric properties over the single quantum dot systems, but also have more means to regulate: it has been shown that the Dicke effect and level detuning play vital roles in improving the thermoelectric efficiency in parallel TQD and T-shaped DQD systems; 20,25 it has also been demonstrated that the magnitude of ZT in a parallel DQD-AB ring system can be considerably enhanced by lead coupling asymmetry, quantum interference effects and magnetic ux. [26][27][28] However, thermoelectric properties based on triangular triple quantum dot (TTQD) systems are not well explored.…”

“…30,[48][49][50][51][52] The few recent studies on two-terminal devices have conrmed that the thermoelectric properties of QD hybrid systems coupled to one conventional lead (metallic or ferromagnetic lead) and one superconducting lead, are remarkably better than those coupled to two conventional leads. 16,28,29,45,47,53 It has been found that the thermoelectric efficiency of the former can even reach several times or even tens of times that of the latter, by comprehensively regulating the superconducting gap, interdot coupling and asymmetric parameters, which can also be additionally enhanced by the interference effect and interdot Coulomb interaction. This is mainly attributed to the unique tunnelling mechanism and high density of states distribution near superconducting gap edges.…”

“…The very high density of states near superconducting gap edges changes rapidly with energy, which is mainly responsible for the high thermopower and low thermal conductivity near the superconducting gap edges. However, recent studies have mainly focused on single quantum dot, 16,47 double quantum dot 28,53 and parallel coupled triple quantum dot systems, 29,45 the thermoelectric properties of TTQD coupling to one metallic-metallic and one superconducting lead have not been studied yet.…”

Phase and Thermal Driven Transport across T-Shaped Double Quantum Dot Josephson Junction

“…Further, the thermoelectric transport properties of systems where the quantum dot is coupled between normal metal and BCS superconductor (N-QD-S) [42,43,44] and ferromagnet and BCS superconductor (F-QD-S) [45,46,47,48] have been studied recently. Further the thermoelectric transport properties of multi-dot and multi-terminal systems with one superconducting lead are also gaining attention [49,50,51,52,53]. Phase and thermal driven transport properties of quantum dot-based Josephson junctions can be analyzed through a combination of three currents: quasi-particle current, interference current, and pair current [54].…”

Enhanced spin-dependent thermopower in a double-quantum-dot sandwiched between two-dimensional electron gases*

“…The magnitude of the thermopower is significantly enhanced in QDsbased structures mainly due to the quantization of the energy levels and the quantum interference effects. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] The latter occurs in multi-path configurations, which induce Aharonov-Bohm effect, [25,26,33,34,43] Fano effect, [33,37] as well as Dicke effect. [39,40,42] Especially, the thermopower has a zero point around the antiresonant states, at each side of which there is a sharp peak.…”