Footprints of hyperfine, spin-orbit, and decoherence effects in Pauli spin blockade

TL;DR

This paper investigates how hyperfine, spin-orbit, and decoherence effects influence the Pauli spin blockade in a double quantum dot, revealing how magnetic fields alter tunneling times and blockade efficiency.

Contribution

It provides real-time measurements of tunneling times and identifies the crossover of blockade lifting mechanisms from hyperfine to spin-orbit interactions under varying magnetic fields.

Findings

Tunneling times T_d and T_b are observed and characterized.

The ratio eta=T_b/T_d varies with magnetic field, indicating changes in blockade efficiency.

The dominant blockade lifting mechanism shifts from hyperfine to spin-orbit interactions as magnetic field increases.

Abstract

We detect in real time inter-dot tunneling events in a weakly coupled two electron double quantum dot in GaAs. At finite magnetic fields, we observe two characteristic tunneling times, T_d and T_b, belonging to, respectively, a direct and a blocked (spin-flip-assisted) tunneling. The latter corresponds to lifting of a Pauli spin blockade and the tunneling times ratio eta=T_b/T_d characterizes the blockade efficiency. We find pronounced changes in the behavior of eta upon increasing the magnetic field, with eta increasing, saturating and increasing again. We explain this behavior as due to the crossover of the dominant blockade lifting mechanism from the hyperfine to spin-orbit interactions and due to a change in the contribution of the charge decoherence.