(NS) Magnetism - PHY00056H

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  • Department: Physics
  • Module co-ordinator: Prof. Sarah Thompson
  • Credit value: 10 credits
  • Credit level: H
  • Academic year of delivery: 2019-20
    • See module specification for other years: 2018-19

Related modules

Co-requisite modules

  • None

Prohibited combinations


Module will run

Occurrence Teaching cycle
A Spring Term 2019-20

Module aims

The magnetism course aims to present an understanding of the origins of diamagnetism, paramagnetism and ferromagnetism and the consequences in particular of ferromagnetism for the behaviour of bulk materials based on a simple description of domain theory. To understand the importance of single domain particles and how their behaviour is controlled and in particular the role of thermal energy in creating disorder at the nanoscale. To have an understanding of the operation of technological applications such as magnetic recording, permanent magnets and soft magnetic materials.

Module learning outcomes

At the end of this module successful students will be able to:

  • A review of the definitions and concepts of magnetism such as flux, flux density and field. Review of units to include the normally used CGS system.
  • Review of ordered magnetism and the role of direct and indirect exchange. Relationship to Curie temperature and Néel temperature.
  • Band theory of ferromagnetism and itinerant ferromagnetism.
  • The concept of the demagnetising field and its role in magnetisation reversal processes.
  • Concept of magnetic anisotropy in terms of crystalline and shape effects and in particular perpendicular anisotropy.
  • Formation of domains, domain walls and hysteresis in bulk materials. The role of the demagnetising field.
  • The origin and concept of single domain materials and reversal via the Stoner Wohlfarth mechanism.
  • Thermal activation and superparamagnetism. Magnetic viscosity and implications for stability e.g. in data storage.
  • Principles of magnetic recording in particular storage perpendicular to the plane.
  • Concept of GMR and TMR (phenomenology only). Design of stacks for GMR and TMR heads.
  • Magnetic recording discs, ECC media and heat assisted magnetic recording.
  • Soft magnetic materials, energy losses and applications.
  • Permanent magnets, operating point, reversal in NdFeB, hybrid systems.

Module content

Please note, students taking this module should have taken Thermodynamics and Solid State II and Mathematics II or appropriate equivalents.

Syllabus

1. Origin and properties associated with diamagnetism and paramagnetism.

2. Ferromagnetism - Curie-Weiss Law, Molecular field, exchange interactions

3. Domain Theory - Demag field, Ems, Domains and walls, Anisotropy - cubic and uniaxial

4. Single Domain Particles - Origin, Stoner-Wohlfarth Model

5. Hysteresis and Thermal Effects - Remanence and Coercivity, SFD, Superparamagnetism

6. Thin Film Magnetism - Thin film growth, Properties, GMR

7. Magnetic Recording - Principles, Disc, Head

8. Permanent Magnets - Basis, BHmax, Nd Fe B

9. Soft Materials - Types, Sources of Loss, Materials and Applications

Assessment

Task Length % of module mark
Essay/coursework
Magnetism Assignment
N/A 14
University - closed examination
Magnetism
1.5 hours 86

Special assessment rules

None

Reassessment

Task Length % of module mark
University - closed examination
Magnetism
1.5 hours 86

Module feedback

Exams - You will receive the marks for the individual exams from eVision. Detailed model answers will be provided on the intranet. You should discuss your performance with your supervisor.

Advice on academic progress - Individual meetings with supervisor will take place where you can discuss your academic progress in detail.

Assignments - Feedback on assignments will be returned within four weeks of the assignment deadline.

Indicative reading

Jiles D: Introduction to Magnetism and Magnetic Materials 2nd Ed (Chapman & Hall)

Cullity B D and C Graham: An Introduction to Magnetic Materials. IEEE Press



The information on this page is indicative of the module that is currently on offer. The University is constantly exploring ways to enhance and improve its degree programmes and therefore reserves the right to make variations to the content and method of delivery of modules, and to discontinue modules, if such action is reasonably considered to be necessary by the University. Where appropriate, the University will notify and consult with affected students in advance about any changes that are required in line with the University's policy on the Approval of Modifications to Existing Taught Programmes of Study.