Quantum Pumping and Nuclear Polarization in the Integer Quantum Hall Regime

TL;DR

This paper investigates charge pumping in a 2D electron gas under quantum Hall conditions, revealing how resonant frequencies induce nuclear polarization and current changes, offering a new method to control and measure nuclear spins.

Contribution

It introduces a quantitative model linking quantum pumping and hyperfine interactions to nuclear polarization in the quantum Hall regime, enabling control and measurement of nuclear spins.

Findings

Resonant pumping induces nuclear polarization.

Step-like changes in pumped current occur at specific frequencies.

The model allows quantitative control of nuclear polarization.

Abstract

We study pumping of charge in a 2DEG in the quantum Hall regime at filling factor $\nu = 2$ (2 spin-split levels of the lowest Landau level). For pumping frequencies that match the Zeeman energy splitting, quantum pumping together with hyperfine interaction between electrons and nuclei induces transitions between the spin-split levels. These lead to a step-like change in the pumped current and to polarization of the nuclei. We present quantitative predictions for both. Our model provides the first quantitative tool to both control and measure the amount of local nuclear polarization in a 2DEG.