micromagnetism nanomagnetism an MMM mini-lecture by Willem van - PowerPoint PPT Presentation

micromagnetism nanomagnetism an MMM mini-lecture by Willem van Engen on October 24, 2007 0 nm μm cm

doi:10.1103/PhysRev.77.725

0.06 T 0.21 T 0.21 T 0.06 T

θ easy axis φ H

easy axis anti-parallel parallel φ = θ = π φ = θ = 0 θ H H H φ

2 E d 2K 2 = 0  H ext =  0 M sat d 

“Micromagnetism and the Microstructure of Ferromagnetic solids”, Kronmüller and Fahnle, 2003. ISBN 0521331358

superparamagnetism 3 = 6 k B T ln  m D th  0  K k B T

single vs. multi domain 18  D do = 2  0 M sat

curling ... “Micromagnetism”, Boardman, 2006. http://www.soton.ac.uk/~rpb/

... or buckling “Development of elongated particle magnets”, Luborsky, 1961. doi:10.1063/1.2000392

Co: D th D nuc D do Fe: D th , D nuc , D do “Development of elongated particle magnets”, Luborsky, 1961. doi:10.1063/1.2000392

enough theory applications!

microfluidics ... “The origins and the future of microfluidics”, Whitesides, 2006. doi:10.1038/nature05058

microfluidics ... ferrofluidics ~10nm + = source: Technorama

microfluidics ... ferrofluidic pump “Magnetism and microfluidics”, Pamme, 2006. doi:10.1039/b513005k

biosensors magnetic bead magnetite grains (Fe 3 O 4 ) surface coating polymer matrix

biosensors biochemical binding Agent Anti body Silicon chip Silicon chip Magnetic field sensor Current wire

biosensors bead attachment & measurement Silicon chip Silicon chip Magnetic field sensor Current wire

vortex switching simulations “Current induced switching of vortex polarity in magnetic nanodisks”, Sheka et al., 2007. doi:10.1063/1.2775036

vortex switching MFM measurements “Electrical switching of the vortex core in a magnetic disk”, Yamada et al., 2007. doi:10.1038/nmat1867

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