Detection of spin injection into a double quantum dot: Violation of magnetic-field-inversion symmetry of nuclear polarization instabilities

TL;DR

This paper demonstrates that electron spin injection into a double quantum dot can be detected by observing the breaking of magnetic-field-inversion symmetry in nuclear polarization instabilities, providing a new experimental approach.

Contribution

It introduces a novel method to identify spin injection in quantum dots through symmetry breaking of nuclear polarization instabilities.

Findings

Asymmetry in instability fields indicates spin injection.

The method detects very weak spin polarization.

Potential applications in spin transport and information processing.

Abstract

In mesoscopic systems with spin-orbit coupling, spin-injection into quantum dots at zero magnetic field is expected under a wide range of conditions. However, up to now, a viable approach for experimentally identifying such injection has been lacking. We show that electron spin injection into a spin-blockaded double quantum dot is dramatically manifested in the breaking of magnetic- field-inversion symmetry of nuclear polarization instabilities. Over a wide range of parameters, the asymmetry between positive and negative instability fields is extremely sensitive to the injected electron spin polarization and allows for the detection of even very weak spin injection. This phenomenon may be used to investigate the mechanisms of spin transport, and may hold implications for spin-based information processing.