We consider a flux-threaded Aharonov-Bohm ring with an embedded quantum dot
coupled to two normal leads. The local Rashba spin-orbit interaction acting on
the dot electrons leads to a spin-dependent phase factor in addition to the
Aharonov-Bohm phase caused by the external flux. Using the numerical
renormalization group method, we find a splitting of the Kondo resonance at the
Fermi level which can be compensated by an external magnetic field. To fully
understand the nature of this compensation effect, we perform a scaling
analysis and derive an expression for the effective magnetic field. The
analysis is based on a tight-binding model which leads to an effective Anderson
model with a spin-dependent density of states for the transformed lead states.
We find that the effective field originates from the combined effect of Rashba
interaction and magnetic flux and that it contains important corrections due to
electron-electron interactions. We show that the compensating field is an
oscillatory function of both the spin-orbit and the Aharonov-Bohm phases.
Moreover, the effective field never vanishes due to the particle-hole symmetry
breaking independently of the gate voltage.Comment: 9 pages, 5 figure
We investigate the thermoelectric properties of a T-shaped double quantum dot system described by a generalized Anderson Hamiltonian. The system's electrical conduction (G) and the fundamental thermoelectric parameters such as the Seebeck coefficient (S) and the thermal conductivity (κ), along with the system's thermoelectric figure of merit (ZT) are numerically estimated based on a Green's function formalism that includes contributions up to the Hartree-Fock level. Our results account for finite onsite Coulomb interaction terms in both component quantum dots and discuss various ways leading to an enhanced thermoelectric figure of merit for the system. We demonstrate that the presence of Fano resonances in the Coulomb blockade regime is responsible for a strong violation of the Wiedemann-Franz law and a considerable enhancement of the system's figure of merit (ZT ).
We study the d -dimensional Bose gas at finite temperature using the renormalization group method. The flow -equations and the free energy have been obtained for dimension d, and the cases d < 2 and d = 2 have been analysed in the limit of low and high temperatures. The critical temperature, the coherence length and the specific heat of a two dimensional Bose gas have been obtained using a solution for the coupling constant which does not present a singular behavior.
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