Electric field and photo-excited control of the carrier concentration in GdN

TL;DR

This paper demonstrates electric and photo-excitation methods to control carrier concentration in GdN, revealing long-lived trap states and challenging previous theories on magnetic interactions.

Contribution

It introduces a novel approach to modulate carrier density in GdN using electric fields and light, and clarifies the role of trap states in its electronic properties.

Findings

Carrier concentration can be controlled electrically and optically in GdN.

Persistent conductivities indicate long-lived trap states, likely at nitrogen vacancies.

No evidence supports carrier-mediated Gd-Gd exchange interaction affecting Curie temperature.

Abstract

We present both electric-field and photo-excited control of the carrier concentration in GdN. There is no evidence in the results of a carrier-mediated contribution to the Gd-Gd exchange interaction that has been suggested to explain a measured Curie temperature that is much higher than obtained within theoretical treatments. Persistent carrier concentrations seen in both the field-effect and photo-induced conductivities point to a distribution of long-lived trap states below the conduction band, very likely centred at nitrogen vacancies