Spin transfer in a ferromagnet-quantum dot and tunnel barrier coupled Aharonov-Bohm ring system with Rashba spin-orbit interactions

TL;DR

This paper investigates how spin transfer torque in a ferromagnet-quantum dot-AB ring system with Rashba spin-orbit interactions can be controlled via magnetic flux and gate voltage, revealing oscillatory behaviors and potential for nanospintronics.

Contribution

It demonstrates the controllability of spin transfer torque through magnetic flux and Rashba interactions in a quantum dot AB ring system, a novel approach for spintronic device manipulation.

Findings

STT magnitude and direction can be tuned by magnetic flux and gate voltage.

STT, current, and spin current oscillate with magnetic flux.

Proper flux and SO matching greatly enhance STT with low current.

Abstract

The spin transfer effect in ferromagnet-quantum dot (insulator)-ferromagnet Aharonov-Bohm (AB) ring system with Rashba spin-orbit (SO) interactions is investigated by means of Keldysh nonequilibrium Green function method. It is found that both the magnitude and direction of the spin transfer torque (STT) acting on the right ferromagnet electrode can be effectively controlled by changing the magnetic flux threading the AB ring or the gate voltage on the quantum dot. The STT can be greatly augmented by matching a proper magnetic flux and an SO interaction at a cost of low electrical current. The STT, electrical current, and spin current are uncovered to oscillate with the magnetic flux. The present results are expected to be useful for information storage in nanospintronics.