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Magnetism in Metal Oxide Nanoparticles Alex Punnoose, Boise State University, DMR 1137419

Magnetism in Metal Oxide Nanoparticles Alex Punnoose, Boise State University, DMR 1137419.

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Magnetism in Metal Oxide Nanoparticles Alex Punnoose, Boise State University, DMR 1137419

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  1. Magnetism in Metal Oxide NanoparticlesAlex Punnoose, Boise State University, DMR 1137419 Training Undergraduates: This work has resulted in two journal articles to be published in the Journal of Applied Physics: “Role of oxygen defects on the magnetic properties of ultra-small Snx-1FexO2 nanoparticles,” and “Correlation between magnetism and electronic structure of Zn1-xCoxO nanoparticles.”. These papers were largely due to work of undergraduates. Outcome: Researchers at Boise Sate University have identified strong correlations between magnetic properties and other physical, and chemical properties of metal oxide materials. Impact: These new discoveries increase our understanding of a novel form of magnetism that has been referred to as “the most interesting new problem in magnetism to emerge so far this century”1. Explanation: Semiconducting metal oxide materials are one of the top candidates for applications in “spintronics”. This technology seeks to harness both the charge and spin properties of electrons and has the potential to decrease power consumption in computers while allowing for further miniaturization. To develop this type of device a material that is both magnetic and semiconducting is needed. Professor Alex Punnoose’s students from left to right: Jordan Chess, Kelsey Dodge, Andrew Lajoie, Catherine Anders, Kate Rainey, Jailes Beltran Jimenez. Not shown in the picture are Nevil Franco and Josh Eixenberger

  2. Magnetism in Oxygen Depleted SnO2Alex Punnoose, Boise State University, DMR 1137419 Annealing Tin Oxide nanoparticles in an inert atmosphere can preferentially remove Oxygen. Using thermogravimetric analysis (TGA) coupled with mass spectrometry we can monitor the preferential removal of Oxygen from SnO2 nanoparticles. X-ray photoelectron spectroscopy (XPS), can be used to quantify the Tin to Oxygen ratio in these samples. Professor Alex Punnoose and his students were able to show that by increasing the Tin to Oxygen ratio they could control the saturation magnetization (Ms) of these particles. The magnetic properties of SnO2samples are shown in the figure. The magnetic strength increases to more than double the original value and linearly increases with the Tin to Oxygen ratio.

  3. Link between magnetic, electronic and structural properties of Zn1-xCoxO nanoparticlesAlex Punnoose, Boise State University, DMR 1137419 Professor Alex Punnoose and his students also found a strong correlation between multiple complimentary physical properties of Cobalt doped Zinc Oxide nanoparticles. The band gap, unit cell volume, saturation magnetization, and Co2+ spin concentration, all have a maximum or minimum at 2.5% cobalt doping. XPS coupled with electron paramagnetic resonance (EPR) reveal that as the dopant concentration increases more of the cobalt ions exist in the Co3+ state than the Co2+ state. Figure shows band gap energy (Eg), unit cell volume, saturation magnetization (Ms), and integrated EPR intensity. Error bars on volume and Ms plots reflect the standard deviation between three independent samples. Error bars on Eg plot indicate uncertainty in peak position.

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