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Magnetism – Experimental group
Properties and applications of ferromagnetic nanostructures
Diego Bisero, Lucia Del Bianco, Federico Spizzo
Outline
1.Nanostructures: some examples
2.Why ferromagnetic nanostructures?
3.Research activity:
● stripe magnetic domains
● nanomagnetic logic gates
● magnetic nanoparticles for biomedical applications
● magnetoplasmonic materials
● magnetic gas sensors
Nanostructures: examples
1D2D 3D
Why nanostructures?
Ferromagnetic nanostructures
By Tem5psu, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35116887
The size of domains and domain walls is comparable with that of the nanostructures
… size affects the properties ...
LThey are small ...
size/shape: new degrees of freedom to affect the magnetic properties
Research area: stripe magnetic domains D. Bisero
● Formation of stripe domains in thin magnetostrictive films with perpendicular magnetic anisotropy (FeGa, TbFeGa)
● Rotation of stripe domains by a magnetic field perpendicular to the stripe axis
This kind of materials may be used as a sensor of mechanical stress or as an actuator
H
Rotatable magnetic anisotropy in thin films with stripe domains
Research area: nanomagnetic logic gates D. Bisero
- Based on silicon transistors - The information is binary (0 and 1 states) and associated to different values of the Voltage - Changing the state of a bit requires the flow of an electric current
Heat generation
Current technological paradigm: CMOS
From thermodinamical considerations, there is a minimal amount of energy required for erasing 1 bit of information:
kBT ln 2
Landauer Limit
Research area: nanomagnetic logic gates D. Bisero
NML-based circuits process information by manipulating the magnetization states of single domain nanomagnets coupled to their nearest neighbors through magnetic dipole interactions.
The state variable is the magnetization direction and computations can take place without the passage of an electric current
Trying to reach the Landauer limit: NanoMagnetic Logic (NML)
The information contained in one dot should be transferred coherently over the longest possible distance:
Nanodot WIRES
D. BiseroExperimental methods: MFM and MOKE
Magnetic Force Microscope (MFM) Magneto Optical Kerr Effect (MOKE)
D. Bisero
D. Bisero office 008 bisero@fe.infn.it
Main collaborations:● University of Notre Dame, Notre Dame, Indiana, USA
(Center for Nano Science and Technology)● University Pierre and Marie Curie, Paris● Universidad Complutense, Madrid● University of Perugia
Solid State Physics – Experimental magnetism groupstripe magnetic domain – nanomagnetic logic gates
master’s degree (LM) thesis
Research area: magnetic nanoparticles for biomedical applications F. Spizzo / L. Del Bianco
Diameter ~ 5 ÷ 10 nm
μ
The nanoparticle is just one magnetic domain
~ giant magnetic moment
magnetic nanoparticle
bio-functionalization layerIncreases the nanoparticles bio-compatibility and affects nanoparticles aggregation
✔ manipulated thanks to a magnetic field
✔ low toxicity✔ high specific surface
✔ If an external AC magnetic field is applied, magnetic nanoparticles may release heat to the tissues (hyperthermia)
Research area: magnetic nanoparticles for biomedical applications F. Spizzo / L. Del Bianco
SPION: SuperParamagnetic Iron Oxide Nanoparticles
Magnetic analysis:
✔ aggregation state✔ relative concentration✔ mutual magnetic interactions✔ nanoparticles-covering interactions✔ nanoparticles-solvent interactions
Experimental methods: SQUID/Mössbauer F. Spizzo / L. Del Bianco
SQUID(superconductive quantum interference device)
Magnetic analysis:
✔ aggregation state✔ relative concentration✔ mutual magnetic interactions✔ nanoparticles-covering interactions✔ nanoparticles-solvent interactions
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Mössbauer spectroscopy (Fe)
Research area: magnetoplasmonic materials L. Del Bianco
Plasmonic resonance
Ligand moleculeDNA / protein
When DNA/protein interact with the ligand molecule, he refractive index of the medium surrounding the nanoparticles changes; due to that, a shift in the position of the absorption maximum is observed.
Magnetoplasmonics: combination of plasmonic and magnetic properties
Research area: magnetoplasmonic materials L. Del Bianco
Magnetoplasmonic material: Au + Co
Growth method: co-sputtering
Au Co
substrate
Aims:● to produce thin films with a fine
intermixing of Au and Co (AuxCo1-x) [NEW!]
● to investigate the magnetic properties of the resulting material
● to use the same material to produce nanostructures for magnetoplasmonic applications
200 nm
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In collaboration with Dep. of Physics and AstronomyUniversity of Padua
Experimental methods: magnetoplasmonic materials L. Del Bianco
Magnetoplasmonic material: Au + Co
Growth method: co-sputtering
Au Co
substrate
Aims:● to produce thin films with a fine
intermixing of Au and Co (AuxCo1-x)
● to investigate the magnetic properties of the resulting material
● to use the same material to produce nanostructures for magnetoplasmonic applications
SQUID
Magneto Optical Kerr Effect (MOKE)
F. Spizzo / L. Del Bianco
L. Del Bianco office 009 lucia.delbianco@unife.itF. Spizzo office 006 spizzo@fe.infn.it
Main collaborations:● Department of Physics and Astronomy, University of Padua● Department of Industrial Engineering, University of Padua● Department of Molecular Biotechnology and Health Sciences, University of Turin● ICMATE-CNR, Padua● University of Perugia
Solid State Physics – Experimental magnetism groupMagnetic nanoparticles for biomedical applications – magnetoplasmonic materials
Bachelor degree (LT) thesis - Master degree (LM) thesis
Research area: magnetic gas sensors B. Fabbri / F. Spizzo
Co: magnetostrictive ferromagnetmechanical stress magnetic properties
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1 2ZnO: piezoelectric semiconductor
electric field structural deformation
Research area: magnetic gas sensors B. Fabbri / F. Spizzo
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electric field structural deformation
Co: magnetostrictive ferromagnetmechanical stress magnetic properties
Research area: magnetic gas sensors B. Fabbri / F. Spizzo
F. Spizzo office 006 spizzo@fe.infn.itB. Fabbri office 110 barbara.fabbri@unife.it
Main collaborations:Elettra - Synchrotron light source - Trieste
Solid State PhysicsExperimental magnetism group & Sensors and Semiconductors group
magnetic gas sensors
Master degree (LM) thesis