Magnetization reversal processes in "bottom-up" and "top-down" magnetic nanostructures
Magnetization reversal processes in "bottom-up" and "top-down" magnetic nanostructures
In this thesis results are presented on the experimental investigation of reversal mechanisms in magnetic nanostructures prepared both using “bottom-up” and “top-down” techniques. Highly ordered magnetic dot arrays and anti-dot networks of Ni, Co and CoPt on sub-micron scales have been prepared using self-assembly single and double template methods. This technique enabled us to create highly ordered magnetic dot and anti-dot nanostructures with 3D architectures on length scales ranging from 20 - 1000 nm. We found that patterning transverse to the film plane, which is a unique feature of this method, results in novel magnetic behaviour. The coercive field Bc, was found to demonstrate an oscillatory dependence on film thickness in anti-dot structures. The magnetization curves of out dot arrays reveal a wealth of different behaviour depending on array parameters. Varying the parameters in the preparation (sphere diameter, film thickness and composition) allows us to produce materials with predetermined magnetic parameters. Results have been interpreted using simple domain wall models and 3D micromagnetic simulations. The self-assembly template offers the potential of a low-cost preparation method for sub-micron patterned magnetic media.
We also studied arrays of different NiFe nanostructures prepared using e-beam lithography. This includes square arrays of anti-dots with various diameters, nano-dots with elliptical shape and aspect ratio a/b ˜ 2, arrays of nano-rings with round and square shapes. Magnetic properties are strongly affected by the shape of the nano-elements. Experimental investigation of the azimuthal behaviour of the coercivity with the magnetic field applied in the plane of the film revealed that magnetostatic energy plays a vital role in the properties of the switching field. All nanostructures in this project have been characterized by bulk magnetometry, MOKE and MFM.
University of Southampton
Goncharov, Alexander
cb8a5b06-6b4e-4ce1-a1a2-f219487a748f
2005
Goncharov, Alexander
cb8a5b06-6b4e-4ce1-a1a2-f219487a748f
Goncharov, Alexander
(2005)
Magnetization reversal processes in "bottom-up" and "top-down" magnetic nanostructures.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In this thesis results are presented on the experimental investigation of reversal mechanisms in magnetic nanostructures prepared both using “bottom-up” and “top-down” techniques. Highly ordered magnetic dot arrays and anti-dot networks of Ni, Co and CoPt on sub-micron scales have been prepared using self-assembly single and double template methods. This technique enabled us to create highly ordered magnetic dot and anti-dot nanostructures with 3D architectures on length scales ranging from 20 - 1000 nm. We found that patterning transverse to the film plane, which is a unique feature of this method, results in novel magnetic behaviour. The coercive field Bc, was found to demonstrate an oscillatory dependence on film thickness in anti-dot structures. The magnetization curves of out dot arrays reveal a wealth of different behaviour depending on array parameters. Varying the parameters in the preparation (sphere diameter, film thickness and composition) allows us to produce materials with predetermined magnetic parameters. Results have been interpreted using simple domain wall models and 3D micromagnetic simulations. The self-assembly template offers the potential of a low-cost preparation method for sub-micron patterned magnetic media.
We also studied arrays of different NiFe nanostructures prepared using e-beam lithography. This includes square arrays of anti-dots with various diameters, nano-dots with elliptical shape and aspect ratio a/b ˜ 2, arrays of nano-rings with round and square shapes. Magnetic properties are strongly affected by the shape of the nano-elements. Experimental investigation of the azimuthal behaviour of the coercivity with the magnetic field applied in the plane of the film revealed that magnetostatic energy plays a vital role in the properties of the switching field. All nanostructures in this project have been characterized by bulk magnetometry, MOKE and MFM.
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Published date: 2005
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Local EPrints ID: 465548
URI: http://eprints.soton.ac.uk/id/eprint/465548
PURE UUID: b9bd74f6-fb99-4e3b-9012-a2f242fc7b86
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Date deposited: 05 Jul 2022 01:43
Last modified: 16 Mar 2024 20:14
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Author:
Alexander Goncharov
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