Iterative path-integral summations for the tunneling magnetoresistance in interacting quantum-dot spin valves

Abstract

We report on the importance of resonant-tunneling processes on quantum transport through interacting quantum-dot spin valves. To include Coulomb interaction in the calculation of the tunneling magnetoresistance (TMR), we reformulate and generalize the recently-developed, numerically-exact method of iterative summation of path integrals (ISPI) to account for spin-dependent tunneling. The ISPI scheme allows us to investigate weak to intermediate Coulomb interaction in a wide range of gate and bias voltage and down to temperatures at which a perturbative treatment of tunneling severely fails. arXiv:1903.11426v2 [cond-mat.mes-hall]

Interaction-induced current asymmetries in resonant transport through interacting quantum-dot spin valves revealed by iterative summation of path integrals

“…different spin-projection expectation values as well as the quantum dot's occupation N and the tunneling current I at measurement time t m . Nonequilibrium properties are taken into account within a functional integral formulation on the Keldysh contour 22,34,35 . Monitoring these observables allows to obtain a complete picture of the spin dynamics of the system.…”

“…, which holds for S i and N , (how to obtain the current is described in Ref. 22). Expectation values may then be computed as…”

“…Current and TMR for transport through a quantum-dot spin valve in collinear setup were also discussed in an earlier work in Ref. 22. The ISPI method excels in the study of the stationary limit while all energy scales of the system are of the same order of magnitude.…”

“…A strong influence of resonant tunneling on the TMR 22 shows that it is essential to include all orders of the tunneling for a complete picture of the electronic transport through small quantum-dot spin valves. For the regime of linear response NRG approaches work well [23][24][25] .…”

Electron Waiting Times in a Strongly Interacting Quantum Dot: Interaction Effects and Higher-Order Tunneling Processes

“…As we will see, the higher-order tunneling processes are predominantly of quantum nature, and they tend to get washed out by an increasing electronic temperature for which we recover a classical description based on sequential tunneling. While we here focus on quantum dots, it will become clear that our approach can be applied to a wide range of interacting nanostructures at low temperatures and bias voltages, where quantum effects are important [53][54][55][56][57][58][59].…”