Spin and charge pumping in a quantum wire: the role of spin-flip scattering and Zeeman splitting

Abstract

We investigate theoretically charge and spin pumps based on a linear configuration of quantum dots (quantum wire) which are disturbed by an external time-dependent perturbation. This perturbation forms an impulse which moves as a train pulse through the wire. It is found that the charge pumped through the system depends non-monotonically on the wire length, N. In the presence of the Zeeman splitting pure spin current flowing through the wire can be generated in the absence of charge current. Moreover, we observe electron pumping in a direction which does not coincide with the propagation direction of the pulse and the spin pumping direction (spin-charge separation). Additionally, on-site spin-flip processes significantly influence electron transport through the system and can also reverse the charge current direction.

Topological Atomic Chains on 2D Hybrid Structure

“…Atomic wires as the thinnest possible electrical conductors are especially interesting objects to study mainly from practical point of view. Their electronic properties are the subject of many theoretical and experimental papers as they reveal a great deal of interesting physical phenomena which are often hard to notice in bulk materials, e.g., spincharge separation [6,7], Majorana topological states [8,9], charge-density waves [10][11][12], turnstile effects, photon-assisted tunneling and pumping effects, or coherent destruction of tunneling [13][14][15][16][17][18][19][20]. In low-dimensional structures one can also observe unique solidstate phases such as time crystals [21][22][23], transient crystals [24] or Floquet topological insulators [25,26].…”

Hierarchical quantum master equation approach to charge transport in molecular junctions with time-dependent molecule-lead coupling strengths

“…27,33,41,42,44,[46][47][48][49][50][51][52][53][54] Based on that, molecular electronic devices such as rectifiers, switches or pumps were proposed that operate by an external field driving the junction. 27,[55][56][57][58][59][60][61][62][63] A variety of theoretical approaches are available to describe electron transport across a molecular junction in the presence of external driving. 31,32,39,[64][65][66] Thereby, the effect of a time-dependent field is described by time-dependent parameters of the Hamiltonian.…”

“…27,[50][51][52]54,63 The coupling between the molecule (or a quantum dot) and the leads, which enables transport in the first place, can also vary in time. This effect was studied theoretically, e.g., in the context of electron shuttles, [68][69][70] charge pumps 62,[71][72][73][74][75][76] and turnstile devices. [77][78][79] Timedependent molecule-lead couplings can also arise in the semi-classical limit as a consequence of current-induced dynamics, [68][69][70][80][81][82] or formally by a unitary transformation of time-dependent energy levels in the leads.…”

Mono-parametric charge pumping through a quantum dot coupled with energy-gapped leads

“…graphene pumps with two vibrating or oscillating potential barriers [17][18][19]. Moreover, spin and charge pumping can occur in low-dimensional systems due to the Zeeman splitting, spin-orbit interactions or in the presence of external train-like impulse (which influences the coupling parameters in the system) [5,[20][21][22]. Such a train impulse a e-mail: tomasz.kwapinski@umcs.pl can be generated by acoustic waves which spread through e.g.…”