Dopant Spin States and Magnetic Interactions in Transition Metal (Fe3+)-Doped Semiconductor Nanoparticles: An EMR and Magnetometric Study

Alex Punnoose, K. M. Reddy, J. Hays, A. Thurber, S. Andronenko, S. K. Misra

Research output: Contribution to journalArticlepeer-review

Abstract

In this work, electron magnetic resonance (EMR) spectroscopy and magnetometry studies were employed to investigate the origin of the observed room-temperature ferromagnetism in chemically synthesized Sn 1- x FexO 2 powders. EMR data clearly established the presence of two different types of signals due to the incorporated Fe ions: paramagnetic spectra due to isolated Fe 3+ ions and broad ferromagnetic resonance (FMR) spectra due to magnetically coupled Fe 3+ dopantions. EMR data analysis and simulation suggested the presence of high-spin ( S = 5/2) Fe 3+ ions incorporated into the SnO 2 host lattice both at substitutional and at interstitial sites. The FMR signal intensity and the saturation magnetization M s of the ferromagnetic component increased with increasing Fe concentration. For Sn 0.953 Fe 0.047 O 2 samples, well-defined EMR spectra revealing FMRs were observed only for samples prepared in the 350–600°C range, whereas for samples prepared at higher annealing temperatures up to 900°C, the FMRs and saturation magnetization were vanished due to diffusion and eventual expulsion of the Fe ions from the nanoparticles, in agreement with data obtained from Raman and X-ray photoelectron spectroscopy.

Original languageAmerican English
JournalPhysics Faculty Publications and Presentations
StatePublished - 1 Dec 2009

EGS Disciplines

  • Physics

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