A new Regime of Pauli-Spin Blockade

TL;DR

This paper theoretically investigates Pauli-spin blockade in double quantum dots under varying magnetic fields, predicting a crossover to reverse blockade at high fields and proposing a method to probe spin relaxation mechanisms in silicon quantum dots.

Contribution

It introduces the concept of reverse PSB at high magnetic fields and links it to the Zeeman and exchange energies, expanding understanding of spin blockade phenomena.

Findings

Identification of a crossover to reverse PSB at high magnetic fields.

Correlation of reverse PSB onset with Zeeman and exchange energy equality.

Potential to probe spin relaxation in silicon quantum dots.

Abstract

Pauli-spin blockade (PSB) is a transport phenomenon in double quantum dots that allows for a type of spin to charge conversion often used to probe fundamental physics such as spin relaxation and singlet-triplet coupling. In this paper we theoretically explore Pauli-spin blockade as a function of magnetic field B applied parallel to the substrate. In the well-studied low magnetic field regime, where PSB occurs in the forward $(1,1)\rightarrow(0,2)$ tunneling direction, we highlight some aspects of PSB that are not discussed in detail in existing literature, including the change in size of both bias triangles measured in the forward and reverse biasing directions as a function of B. At higher fields we predict a crossover to \reverse PSB" in which current is blockaded in the reverse direction due to the occupation of a spin singlet as opposed to the traditional triplet blockade that occurs at low fields. The onset of reverse PSB coincides with the development of a tail like feature in the measured bias triangles and occurs when the Zeeman energy of the polarized triplet equals the exchange energy in the (0,2) charge configuration. In Si quantum dots these fields are experimentally accessible; thus, this work suggests a way to probe singlet to triplet relaxation mechanisms in quantum dots when both electrons occupy the same quantum dot.