nano magnetic interactions on mnas thin films

Nano-magnetic interactions Nano-magnetic interactions on MnAs thin filmson MnAs thin films

Raphael BouskilaRaphael BouskilaM.Sc. CandidateM.Sc. Candidate

Burch Group, University of TorontoBurch Group, University of Toronto

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OutlineOutline MotivationMotivation ObjectivesObjectives Description of proposed experimentDescription of proposed experiment Further research ideasFurther research ideas

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MotivationMotivation What are we trying to do here?What are we trying to do here? We are studying the interactions of We are studying the interactions of

ferromagnetic domains on the nanoscaleferromagnetic domains on the nanoscale

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MotivationMotivation Example application: BiosensorsExample application: Biosensors

– Chemical purity measurementsChemical purity measurements– Drug uptake measurementsDrug uptake measurements– Organic molecule selection via functionalized Organic molecule selection via functionalized

nanoparticlesnanoparticles

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MotivationMotivation Example: DNA strings ligated to magnetic Example: DNA strings ligated to magnetic

nanoparticles (e.g., Horák, nanoparticles (e.g., Horák, J. Mag. & Mag. J. Mag. & Mag. Mater.Mater. 311 311 249 (2007))249 (2007))– Specific DNA/RNA strings attach to the Specific DNA/RNA strings attach to the

particles, and then the DNA can be selected particles, and then the DNA can be selected out via the properties of the particle attached out via the properties of the particle attached to itto it

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IntroductionIntroduction MnAs: two-phase MnAs: two-phase

system near RTsystem near RT– Domain width: ~100 Domain width: ~100

nmnm– Period: ~200 nmPeriod: ~200 nm

Can be controlled via:Can be controlled via:– Optical excitationOptical excitation– Ambient temperatureAmbient temperature

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IntroductionIntroduction

α-MnAs(ferromagnetic)

β-MnAs(paramagnetic)

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IntroductionIntroduction MnAs in profile:MnAs in profile:

GaAs (001) substrate

H

α-MnAs

β-MnAs

60 nm

100 nm

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IntroductionIntroduction Alternatively:Alternatively:

GaAs (001) substrate

H

α-MnAs

β-MnAs

60 nm

100 nm

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IntroductionIntroduction Goh group (Dept. of Chemistry, University Goh group (Dept. of Chemistry, University

of Toronto), produces ferromagnetic of Toronto), produces ferromagnetic nanoparticlesnanoparticles– ~10-20 nm diameter~10-20 nm diameter– Composed of iron oxideComposed of iron oxide– Water-solubleWater-soluble

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ObjectivesObjectives Proof-of-concept idea:Proof-of-concept idea:

GaAs (001) substrate

H

60 nm

100 nm

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MethodMethod

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ResultsResults

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ResultsResults

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ResultsResults

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ResultsResults

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Further ideasFurther ideas Do different nanowire widths preferentially Do different nanowire widths preferentially

trap different sizes of nanoparticle?trap different sizes of nanoparticle? Could a temperature or optical energy Could a temperature or optical energy

gradient sort particles by size?gradient sort particles by size? Can this method be used as a “poor man’s Can this method be used as a “poor man’s

MFM” technique?MFM” technique? Can this method be used to align Can this method be used to align

nanoparticles into arbitrary patterns?nanoparticles into arbitrary patterns?

Thanks!Thanks!