Carbon p Electron Ferromagnetism in Silicon Carbide

Yutian Wang,Ovidiu D Gordan,Dietrich R T Zahn,Shengqiang Zhou,Manfred Helm,Yu Liu,Sibylle Gemming,Wolfgang Anwand,Frans Munnik,Georgeta Salvan,Xiaolong Chen,Gang Wang,Catherine A Jenkins,Elke Arenholz

doi:10.1038/srep08999

Abstract

Ferromagnetism can occur in wide-band gap semiconductors as well as in carbon-based materials when specific defects are introduced. It is thus desirable to establish a direct relation between the defects and the resulting ferromagnetism. Here, we contribute to revealing the origin of defect-induced ferromagnetism using SiC as a prototypical example. We show that the long-range ferromagnetic coupling can be attributed to the p electrons of the nearest-neighbor carbon atoms around the VSiVC divacancies. Thus, the ferromagnetism is traced down to its microscopic electronic origin.

Highlights

Ferromagnetism can occur in wide-band gap semiconductors as well as in carbon-based materials when specific defects are introduced
The dynamics of defects and their charge states in SiC upon ion irradiation can be obtained by ab initio molecular dynamics simulations[23], rendering SiC an ideal testbed for the investigation of defect-induced ferromagnetism
We present the results of X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) experiments at both the silicon and carbon K-edges in conjunction with sensitive magnetization measurements and first-principles calculations

Summary

Introduction

Ferromagnetism can occur in wide-band gap semiconductors as well as in carbon-based materials when specific defects are introduced. Unexpected ferromagnetism has been observed or theoretically predicted for numerous defective carbon based materials and wide-band gap semiconductors such as highly oriented pyrolytic graphite (HOPG), graphene, oxides and SiC1–12, which provides an alternative for organic and semiconductor spintronics. Cervenka et al.[13] demonstrated direct evidence that localized electron states at grain boundaries were one of the origins to induce ferromagnetism in HOPG. We present the results of X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) experiments at both the silicon and carbon K-edges in conjunction with sensitive magnetization measurements and first-principles calculations These results show that the p electrons of the nearest-neighbor carbon atoms of VSiVC are mainly responsible for the long-range ferromagnetic coupling. Our results provide important evidence for the origin of defect-induced ferromagnetism in SiC

Methods

Results

Conclusion