Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555664
Title: Alternative magnetic recording technologies
Author: Bashir, Muhammad Asif
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
Availability of Full Text:
Access from EThOS:
Abstract:
Presented here are micromagnetic simulations to investigate alternative magnetic recording technologies including bit patterned media and domain wall storage. I have used a finite element/boundary element method to investigate the dynamics of the write process in magnetic recording systems; and a nudged elastic band method is used to calculate the thermal stability of written bits. Microwave assisted magnetization reversal of single phase media and exchange spring media is investigated. A reduction of the switching field by about a factor of two can be found in both single phase and exchange spring media when the microwave field reaches an amplitude that is 12 percent of the remanent coercivity without microwave assist. Furthermore, layer-selective writing of two-layer bitpatterned media is demonstrated by employing microwave assist technique. Selectivity is achieved by controlling the frequency of an oscillating magnetic field in the GHz range, applied in addition to the head field. Generation of the microwave field by means of a wire next to the tip of a single pole head is proposed. Optimization of writing heads is performed using micromagnetics and surrogate optimization. The shape of the pole tip is optimized for bit patterned, exchange spring recording media. I computed the write error rate and the adjacent track erasure for different maximum anisotropy in the multilayer, graded media. The results show a linear trade off between the error rate and the number of passes. Finally I have calculated magneto static fields from transverse and vortex magnetic domain walls in a planar Ni81Fe19 nanowire. These calculations indicate the required sensitivity of a nearby sensor for detecting either a domain wall of any type or being able to distinguish the domain wall character. Optimization of writing heads is performed using micromagnetics and surrogate optimization. The shape of the pole tip is optimized for bit patterned, exchange spring recording media. I computed the write error rate and the adjacent track erasure for different maximum anisotropy in the multilayer, graded media. The results show a linear trade off between the error rate and the number of passes. Finally I have calculated magneto static fields from transverse and vortex magnetic domain walls in a planar Ni81Fe19 nanowire. These calculations indicate the required sensitivity of a nearby sensor for detecting either a domain wall of any type or being able to distinguish the domain wall character.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.555664  DOI: Not available
Share: