Transport through a quantum dot subject to spin and charge bias

Abstract

Spin and charge transport through a quantum dot coupled to external nonmagnetic leads is analyzed theoretically in terms of the non-equilibrium Green function formalism based on the equation of motion method. The dot is assumed to be subject to spin and charge bias, and the considerations are focused on the Kondo effect in spin and charge transport. It is shown that the differential spin conductance as a function of spin bias reveals a typical zero-bias Kondo anomaly which becomes split when either magnetic field or charge bias are applied. Significantly different behavior is found for mixed charge/spin conductance.The influence of electron-phonon coupling in the dot on tunneling current as well as on both spin and charge conductance is also analyzed.

Beating in electronic transport through quantum dot based devices

“…we assume that µ Sj↑ = µ D↓ and µ Sj↓ = µ D↑ for (j = 1, 2). Introducing the spin bias V s , generally we may write µ Sjσ = e(V +σV s )/2 and µ Dσ = −e(V +σV s )/2 withσ = 1 (σ = −1) for σ =↑ (σ =↓) 37 . As we are interested in pure spin current we further set bias voltage equal to zero V = 0.…”

“…However, it is worth to mention that when the dot's energy level is split i.e., ǫ ↑ = ǫ ↓ , the nonzero charge current can be generated 32,37,38 . In Fig.8 we show time evolution of the spin current calculated for different strengths of the intradot Coulomb interactions.…”

Entanglement Negativity and Concurrence in Some Low-Dimensional Spin Systems

“…[ 23 ], the interactions between magnons or spinons with defects in the lattice and phonons have generated a number of intriguing features [ 24 , 25 , 26 , 27 , 28 , 29 ]. In addition, the spin–lattice interaction’s magnetic systems for example, leads to modifications in the spectrum of spin excitations [ 30 , 31 , 32 ] and to the formation of new phases, such as the spin-Peierls dimerized phase. Thus, we investigated the effects of different quantum and topological phase transitions induced by the spin-couplings, as well as the dimensionality and geometry of the lattice on quantum correlation and entanglement in Refs.…”

A non-equilibrium equation-of-motion approach to quantum transport utilizing projection operators

“…A simple general alternative is the equation-of-motion (EOM) method 42,43 formulated for transport problems on the Keldysh contour. [44][45][46][47][48][49][50][51][52][53] EOM permits working with correlation functions of any operators to produce (in general) an infinite chain of equations of motion. The main drawback of the method is the necessity to make an uncontrolled approximation to close the chain of equations.…”