Impact of Kondo correlations and spin-orbit coupling on spin-polarized transport in carbon nanotube quantum dot

TL;DR

This paper investigates how Kondo correlations and spin-orbit coupling influence spin-polarized transport in carbon nanotube quantum dots, revealing effects on spin currents, TMR, and the role of magnetization orientation.

Contribution

It introduces a detailed analysis of spin transport considering noncollinear magnetizations, spin-orbit coupling, and Kondo effects using nonequilibrium Green functions.

Findings

Spin-orbit coupling can reverse tunneling magnetoresistance sign.

Magnetization orientation affects pure spin current at zero bias.

Spin-flip currents emerge due to noncollinear magnetizations.

Abstract

Spin polarized transport through a quantum dot coupled to ferromagnetic electrodes with noncollinear magnetizations is discussed in terms of nonequilibrium Green functions formalism in the finite-U slave boson mean field approximation. The difference of orientations of the magnetizations of electrodes opens off-diagonal spin-orbital transmission and apart from spin currents of longitudinal polarization also spin-flip currents appear. We also study equilibrium pure spin current at zero bias and discuss its dependence on magnetization orientation, spin-orbit coupling strength and gate voltage. Impact of these factors on tunneling magnetoresistance (TMR) is also undertaken. In general spin-orbit coupling weakens TMR, but it can change its sign.