Tuning the polarization states of optical spots at the nanoscale on the poincar´e sphere using a plasmonic nanoantenna

It is shown that the polarization states of optical spots at the nanoscale can be manipulated to various points on the Poincar´e sphere using a plasmonic nanoantenna. Linearly, circularly, and elliptically polarized near-field optical spots at the nanoscale are achieved with various polarization states on the Poincar´e sphere using a plasmonic nanoantenna. A novel plasmonic nanoantenna is illuminated with diffraction-limited linearly polarized light. It is demonstrated that the plasmonic resonances of perpendicular and longitudinal components of the nanoantenna and the angle of incident polarization can be tuned to obtain optical spots beyond the diffraction limit with a desired polarization and handedness

Laser Induced Femtosecond magnetic Recording

Contains fulltext : 65585_lasefemar.pdf (publisher's version ) (Open Access)A hard disk drive (HDD) stores information in the form of small magnetic areas magnetized in opposite directions, like tiny bar magnets pointing north or south. Depending on the orientation of these bits the information can be later retrieved as 'ones' and 'zeros'. The conventional way to reverse a magnetic bit is by applying a magnetic field pulse. Although today a HDD stores a magnetic bit in ~1 nanosecond, the speed of this process was expected to be as high as desired, provided that sufficiently high fields would be available. However, it was recently predicted that no matter how short and strong the magnetic field pulse is, there is a natural limit of switching the magnetic bit on the picosecond time scale, beyond which magnetization reversal becomes chaotic [I. Tudosa et al., Nature 428, 831 (2004)]. Thus, finding new approaches to reverse magnetization in a reproducible way, on a time scale shorter than picoseconds, is a fundamental challenge with important consequences for magnetic data storage technology. This thesis demonstrates that the magnetic bit can be switched on a timescale shorter than picosecond by firing a very short pulse of circularly-polarized laser light at it. No external magnetic field was required to flip the bit. This means that that the bit value could be changed ~50.000 times faster than the fastest conventional memory, thus breaking what was previously called the speed limit of magnetic recording.Radboud Universiteit Nijmegen, 03 oktober 2008Promotor : Rasing, T.H.M.135 p

Entropic model and optimization of a refrigeration machine

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Optical excitation of antiferromagnetic resonance in TmFeO3

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Ultrafast interaction of the angular momentum of photons with spins in the metallic amorphous alloy GdFeCo

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All-optical magnetic recording with circularly polarized light

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Ultrafast spin dynamics across compensation points in ferrimagnetic GdFeCo: The role of angular momentum compensation

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Subpicosecond magnetization reversal across ferrimagnetic compensation points

Contains fulltext : 36522.pdf (publisher's version ) (Open Access

Characterisation of the Fe-10 wt% Si nanocrystalline powder obtained by mechanical alloying and annealing

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