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Micromagnetic studies of three-dimensional pyramidal shell-structures

Micromagnetic studies of three-dimensional pyramidal shell-structures
Micromagnetic studies of three-dimensional pyramidal shell-structures
In this article we present a systematic, numerical analysis of the magnetic properties of pyramidal-shaped core-shell structures in a size range below 400nm.
These are three dimensional structures consisting of a ferromagnetic shell which is grown on top of a non-magnetic core. The standard micromagnetic model without the
magnetocrystalline anisotropy term is used to describe the properties of the shell. We vary the thickness of the shell between the limiting cases of an ultra thin shell and a conventional pyramid and delineate different stable magnetic configurations. We find different kinds of single domain states, which predominantly occur at smaller system
sizes. In analogy to equivalent states in thin square films we term these onion, flower, C, and S state. At larger system sizes we also observe two types of vortex states, which we refer to as symmetric and asymmetric vortex state. For a classification of the observed states, we derive a phase diagram which specifies the magnetic ground state as a function of structure size and shell thickness. The transitions between different ground states can be understood qualitatively. We address the issue of
metastability by investigating the stability of all occurring configurations for different shell thicknesses. For selected geometries and directions hysteresis measurements are analysed and discussed. We observe that the magnetic behaviour changes distinctively in the limit of ultra-thin shells. The study has been motivated by the recent progress made in the growth of faceted core-shell structures.
113048
Knittel, Andreas
f2336826-cc4d-4362-a241-1bf90c4941d4
Franchin, Matteo
9e00aaa2-959e-420f-854c-3b43aece85e3
Fischbacher, Thomas
d3282f31-0a6a-4d19-80d0-e3bebc12f67a
Nasirpouri, F.
ba34ed11-f7bf-44b9-82d6-df2d6ebd9711
Bending, S.
b1f6912d-f315-4bb9-8a9e-1d29b10cd442
Fangohr, Hans
9b7cfab9-d5dc-45dc-947c-2eba5c81a160
Knittel, Andreas
f2336826-cc4d-4362-a241-1bf90c4941d4
Franchin, Matteo
9e00aaa2-959e-420f-854c-3b43aece85e3
Fischbacher, Thomas
d3282f31-0a6a-4d19-80d0-e3bebc12f67a
Nasirpouri, F.
ba34ed11-f7bf-44b9-82d6-df2d6ebd9711
Bending, S.
b1f6912d-f315-4bb9-8a9e-1d29b10cd442
Fangohr, Hans
9b7cfab9-d5dc-45dc-947c-2eba5c81a160

Knittel, Andreas, Franchin, Matteo, Fischbacher, Thomas, Nasirpouri, F., Bending, S. and Fangohr, Hans (2010) Micromagnetic studies of three-dimensional pyramidal shell-structures. New Journal of Physics, 12, 113048.

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Abstract

In this article we present a systematic, numerical analysis of the magnetic properties of pyramidal-shaped core-shell structures in a size range below 400nm.
These are three dimensional structures consisting of a ferromagnetic shell which is grown on top of a non-magnetic core. The standard micromagnetic model without the
magnetocrystalline anisotropy term is used to describe the properties of the shell. We vary the thickness of the shell between the limiting cases of an ultra thin shell and a conventional pyramid and delineate different stable magnetic configurations. We find different kinds of single domain states, which predominantly occur at smaller system
sizes. In analogy to equivalent states in thin square films we term these onion, flower, C, and S state. At larger system sizes we also observe two types of vortex states, which we refer to as symmetric and asymmetric vortex state. For a classification of the observed states, we derive a phase diagram which specifies the magnetic ground state as a function of structure size and shell thickness. The transitions between different ground states can be understood qualitatively. We address the issue of
metastability by investigating the stability of all occurring configurations for different shell thicknesses. For selected geometries and directions hysteresis measurements are analysed and discussed. We observe that the magnetic behaviour changes distinctively in the limit of ultra-thin shells. The study has been motivated by the recent progress made in the growth of faceted core-shell structures.

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Published date: 26 November 2010

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Local EPrints ID: 159209
URI: https://eprints.soton.ac.uk/id/eprint/159209
PURE UUID: eae10126-2a3f-4f7a-8d18-714d5e24f0bb

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Date deposited: 28 Jun 2010 13:52
Last modified: 18 Jul 2017 12:37

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Contributors

Author: Andreas Knittel
Author: Matteo Franchin
Author: Thomas Fischbacher
Author: F. Nasirpouri
Author: S. Bending
Author: Hans Fangohr

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