Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism
Abstract
Defect-induced ferromagnetism has triggered a lot of investigations and controversies. The major issue is that the induced ferromagnetic signal is so weak that it can sufficiently be accounted for by trace contamination. To resolve this issue, we studied the variation of the magnetic properties of SiC after neutron irradiation with fluence covering four orders of magnitude. A large paramagnetic component has been induced and scales up with defect concentration, which can be well accounted for by uncoupled divacancies. However, the ferromagnetic contribution is still weak and only appears in the low fluence range of neutrons or after annealing treatments. First-principles calculations hint towards a mutually exclusive role of the concentration of defects: Defects favor spin polarization at the expense of magnetic interaction. Combining both experimental and first-principles calculation results, the defect-induced ferromagnetism can be understood as a local effect which cannot be scaled up with the volume. Therefore, our investigation answers the long-standing question why the defect-induced ferromagnetic signal is weak.
Cite
@article{arxiv.1501.01096,
title = {Defect-induced magnetism in SiC: Interplay between ferromagnetism and paramagnetism},
author = {Yutian Wang and Yu Liu and Elke Wendler and René Hübner and Wolfgang Anwand and Gang Wang and Xuliang Chen and Wei Tong and Zhaorong Yang and Frans Munnik and Gregor Bukalis and Xiaolong Chen and Sibylle Gemming and Manfred Helm and Shengqiang Zhou},
journal= {arXiv preprint arXiv:1501.01096},
year = {2015}
}
Comments
30 pages, 14 figures