Controlled Spin Transport in Planar Systems Through Topological Exciton

TL;DR

This paper demonstrates that topologically protected, neutral spin-1 excitons in planar systems like graphene can enable controlled spin transport, resilient to charge-related disturbances, with their stability influenced by quantum and thermal fluctuations.

Contribution

It introduces a novel type of topologically stabilized, neutral exciton in planar systems, enabling controlled spin transport with potential robustness against charge-related noise.

Findings

Existence of a topological, neutral spin-1 exciton in planar systems.

Exciton stability is affected by quantum and thermal fluctuations.

Coupling of the exciton to magnetic fields allows for controlled spin transport.

Abstract

It is shown that a charge-neutral spin-1 exciton, realizable only in planar systems like graphene, can effectively be used for controlled spin transport in such media. The excitonic bound state is destabilized by quantum fluctuations, characterized by a threshold for excitation and melts in a smooth manner under thermal fluctuations. This planar exciton differs from the conventional ones, as it owes its existence to the topological Chern-Simons (CS) term. The parity and time-reversal violating CS term can arise from quantum effects in systems with parity-breaking mass-gap. The spinning exciton naturally couples to magnetic field, leading to the possibility of controlled spin transport. Being neutral, it is immune to adverse effects, afflicting spin transport by charged fermions.