Element-specific characterization of heterogeneous magnetism in (Ga,Fe)N films
2012 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 18, 184411- p.Article in journal (Refereed) Published
We employ x-ray spectroscopy to characterize the distribution and magnetism of particular alloy constituents in (Ga,Fe)N films grown by metal organic vapor phase epitaxy. Furthermore, photoelectron microscopy gives direct evidence for the aggregation of Fe ions, leading to the formation of Fe-rich nanoregions adjacent to the samples surface. A sizable x-ray magnetic circular dichroism (XMCD) signal at the Fe L edges in remanence and at moderate magnetic fields at 300 K links the high-temperature ferromagnetism with the Fe(3d) states. A sizable value of the orbital moment measured in remanence points to a large magnetic anisotropy and to a correspondingly high blocking temperature, which can stabilize the ferromagnetic-like response of the Fe-rich nanocrystals at 300 K. The XMCD response at the N K edge highlights that the N(2p) states, due to exchange coupling to Fe ions, carry considerable spin polarization. These results, supported by ab initio studies of XMCD spectra for various FeN delta nanocrystals, demonstrate that nanocrystals with delta > 0.25 account for the ferromagnetic behavior of (Ga,Fe)N films.
Place, publisher, year, edition, pages
2012. Vol. 85, no 18, 184411- p.
IdentifiersURN: urn:nbn:se:uu:diva-175192DOI: 10.1103/PhysRevB.85.184411ISI: 000303910600004OAI: oai:DiVA.org:uu-175192DiVA: diva2:531875