The University of Southampton
University of Southampton Institutional Repository

Magnetoresistance in constrained domain walls

Magnetoresistance in constrained domain walls
Magnetoresistance in constrained domain walls
In magnetic materials, domains of magnetic orientation in opposite direction are often alternated. The transition in orientation between these domains, the domain wall, is not abrupt but spatially extended. When a current is passed through the magnetic material, the resistance of the material is dependent on whether such domain wall exists, which in its turn depends on the external magnetic field. This magneto-resistance is larger for smaller domain walls. Although the domain wall width is in principle a materials parameter, by patterning the magnetic sample into certain nanostructures, it is possible to constrain the domain wall such that its width is smaller than its natural unconstrained width.

We have measured domain wall magnetoresistance in a single lithographically constrained domain wall. An H-shaped Ni nanobridge was fabricated by either e-beam lithography or a combination of e-beam lithography and helium ion milling. The two sides of the device are both single magnetic domains showing independent magnetic switching. The connection between the sides constrains the domain wall when the sides line up antiparallel. The magnetoresistance curve clearly identifies the magnetic configurations that are expected from a spin-valve like structure.

The room temperature domain wall measurements give a magneto-resistance ratio of 0.1 % for the 94 nm and 0.2 % for the 32 nm constriction. Although these values are in itself small, they are the first results on lithographically prepared single domain spin valves. The single-layered device might allow for easier fabrication and space savings for high dense storage applications as compared to giant magneto-resistance and tunneling magneto-resistance. Also, the research of spin-based logic devices will benefit from the physical understanding that follows from measurements of magneto-resistance devices without material interface.
Wang, Yudong
c48bcc7c-4cb4-468c-af4e-d1e601222009
Wang, Yudong
c48bcc7c-4cb4-468c-af4e-d1e601222009
De Groot, Cornelis
92cd2e02-fcc4-43da-8816-c86f966be90c

(2013) Magnetoresistance in constrained domain walls. University of Southampton, Faculty of Physical Science & Engineering, Doctoral Thesis, 135pp.

Record type: Thesis (Doctoral)

Abstract

In magnetic materials, domains of magnetic orientation in opposite direction are often alternated. The transition in orientation between these domains, the domain wall, is not abrupt but spatially extended. When a current is passed through the magnetic material, the resistance of the material is dependent on whether such domain wall exists, which in its turn depends on the external magnetic field. This magneto-resistance is larger for smaller domain walls. Although the domain wall width is in principle a materials parameter, by patterning the magnetic sample into certain nanostructures, it is possible to constrain the domain wall such that its width is smaller than its natural unconstrained width.

We have measured domain wall magnetoresistance in a single lithographically constrained domain wall. An H-shaped Ni nanobridge was fabricated by either e-beam lithography or a combination of e-beam lithography and helium ion milling. The two sides of the device are both single magnetic domains showing independent magnetic switching. The connection between the sides constrains the domain wall when the sides line up antiparallel. The magnetoresistance curve clearly identifies the magnetic configurations that are expected from a spin-valve like structure.

The room temperature domain wall measurements give a magneto-resistance ratio of 0.1 % for the 94 nm and 0.2 % for the 32 nm constriction. Although these values are in itself small, they are the first results on lithographically prepared single domain spin valves. The single-layered device might allow for easier fabrication and space savings for high dense storage applications as compared to giant magneto-resistance and tunneling magneto-resistance. Also, the research of spin-based logic devices will benefit from the physical understanding that follows from measurements of magneto-resistance devices without material interface.

PDF
Thesis_YudongWang_FinalSubmission.pdf - Other
Download (23MB)

More information

Published date: April 2013
Organisations: University of Southampton, Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 350881
URI: http://eprints.soton.ac.uk/id/eprint/350881
PURE UUID: 0b011165-c787-42ec-a8a1-963f85764ffe
ORCID for Cornelis De Groot: ORCID iD orcid.org/0000-0002-3850-7101

Catalogue record

Date deposited: 09 Apr 2013 14:08
Last modified: 06 Jun 2018 12:50

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×