Large spin splitting of GaN electronic states induced by Gd doping

TL;DR

This study demonstrates that Gd doping in GaN causes a significant and reversible spin splitting of the valence band, revealing long-range magnetic interactions in the material.

Contribution

It provides the first detailed analysis of how Gd doping induces large, reversible spin splitting in GaN's electronic states, highlighting long-range magnetic effects.

Findings

Gd doping causes a strong spin splitting in GaN

Spin splitting reverses sign at low Gd concentrations

Magnetic moments are induced over long ranges in GaN

Abstract

We present a detailed study of the magnetic-field and temperature-dependent polarization of the near-band-gap photoluminescence in Gd-doped GaN layers. Our study reveals an extraordinarily strong influence of Gd doping on the electronic states in the GaN matrix. We observe that the spin splitting of the valence band reverses its sign for Gd concentrations as low as 1.6 x 10^{16} cm^{-3}. This remarkable result can be understood only in terms of a long range induction of magnetic moments in the surrounding GaN matrix by the Gd ions.