Voltage control of nuclear spin in ferromagnetic Schottky diodes

TL;DR

This study demonstrates voltage-controlled nuclear spin polarization in ferromagnetic Schottky diodes using optical spectroscopy, revealing tunable nuclear fields and their relation to diode turn-on.

Contribution

It introduces a method to electrically tune nuclear spin polarization in ferromagnetic semiconductor diodes, a novel approach in spintronics.

Findings

Nuclear polarization can be tuned from <0.05 to 2.4 kG by bias voltage.

Nuclear polarization correlates with diode turn-on.

Dynamic nuclear polarization shows minimal voltage dependence.

Abstract

We employ optical pump-probe spectroscopy to investigate the voltage dependence of spontaneous electron and nuclear spin polarizations in hybrid MnAs/n-GaAs and Fe/n-GaAs Schottky diodes. Through the hyperfine interaction, nuclear spin polarization that is imprinted by the ferromagnet acts on conduction electron spins as an effective magnetic field. We demonstrate tuning of this nuclear field from <0.05 to 2.4 kG by varying a small bias voltage across the MnAs device. In addition, a connection is observed between the diode turn-on and the onset of imprinted nuclear polarization, while traditional dynamic nuclear polarization exhibits relatively little voltage dependence.