Nuclear spin induced oscillatory current in spin-blocked quantum dots

TL;DR

This paper investigates how hyperfine interactions between electron and nuclear spins in GaAs quantum dots cause long-period oscillations in current, which can be controlled by magnetic fields and nuclear resonance effects.

Contribution

It demonstrates the influence of nuclear spins on electron transport in quantum dots and proposes a nuclear spin polarization mechanism via hyperfine flip-flop scattering.

Findings

Current oscillations with periods up to 200 seconds observed.

Oscillations diminish under AC magnetic fields at nuclear resonance frequencies.

Hyperfine flip-flop scattering proposed as a nuclear polarization mechanism.

Abstract

Hyperfine coupling of electron spins to nuclear spins is studied for a GaAs-based double quantum dot in the spin blockade regime where the electron conduction is mostly blocked by Pauli effect unless the electron spin state in the double dot is changed. A current flowing through the double dot shows time-dependent oscillations with a period of as long as 200 sec in a certain DC magnetic field range. The oscillatory behavior is significantly diminished by application of an AC magnetic field whose frequency can induce nuclear magnetic resonance for 71Ga and 69Ga, respectively. A possible nuclear spin polarization mechanism due to hyperfine flip-flop scattering is proposed.