Magnetic Properties of a-Si films doped with rare-earth elements

TL;DR

This study investigates the magnetic properties of amorphous silicon films doped with various rare-earth elements, revealing strong exchange interactions and stable RE-Si complexes, with implications for magnetic material design.

Contribution

It provides new insights into the magnetic interactions and structural incorporation of rare-earth elements in amorphous silicon films, especially highlighting differences between magnetic and non-magnetic dopants.

Findings

RE3+ ions are incorporated in a-Si:RE in the RE3+ form.

RE doping reduces the neutral dangling bonds, more so for magnetic REs.

Gd-doped films show a stable ESR Gd3+ resonance indicating RE-Si complex formation.

Abstract

Amorphous silicon films doped with Y, La, Gd, Er, and Lu rare-earth elements (a-Si:RE) have been prepared by co-sputtering and studied by means of electron spin resonance (ESR), dc-magnetization, ion beam analysis, optical transmission, and Raman spectroscopy. For comparison the magnetic properties of laser-crystallized and hydrogenated a-Si:RE films were also studied. It was found that the rare-earth species are incorporated in the a-Si:RE films in the RE3+ form and that the RE-doping depletes the neutral dangling bonds (D0) density. The reduction of D0 density is significantly larger for the magnetic REs (Gd3+ and Er3+) than for the non-magnetic ones (Y3+, La3+, Lu3+). These results are interpreted in terms of a strong exchange-like interaction, J RE-DB SRE SDB, between the spin of the magnetic REs and that of the D0. All our Gd-doped Si films showed basically the same broad ESR Gd3+ resonance (DHpp ~ 850 Oe) at g ~ 2.01, suggesting the formation of a rather stable RE-Si complex in these films.