Nanoscale & Magnetism - PHY00043H

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

Related modules

Co-requisite modules

  • None

Additional information

Please note, the magnetism component of the module requires some knowledge of crystal structures, electron densities of states and band structures such as covered in the pre-requisite Solid State I module and Stage 2 Statistical Mechanics. Natural Science students who have not taken these modules, are still welcome, and will be supported by directed reading and an optional additional tutorial.

Module will run

Occurrence Teaching cycle
A Autumn Term 2019-20 to Spring Term 2019-20

Module aims

This module aims to give students a working understanding of the physics and terminology of magnetism, magnetic materials, and techniques for investigating materials on the nanoscale.

The magnetism course aims aims to present an understanding of the origins of diamagnetism, paramagnetism and ferromagnetism and the magnetisation process. This fundamental knowledge is then applied to the design of soft and hard magnetic materials, magnetic nanoparticles, magnetic thin films and multilayers; and their applications. The module extends into the development of the modern magnetic technologies of magnetic data storage, memory and spintronics.

Analysing the Nanoscale course presents an overview to the current interest and challenges in the burgeoning area of nanoscience and nanotechnology, and introduces you to some of the state-of-the-art techniques required to characterise materials on the nanoscale. Nanoscience and nanotechnology is defined as relating to the study and creation of structures which have dimensions of less than 100 nanometres. This course will focus on two main themes:

(i) understanding some of the properties of solid materials when dimensions are reduced to nanometre length scales; and

(ii) the principles underlying, and application of, some key characterisation and analysis instruments and techniques which enable the study of solid materials on the nano to atomic scale.

Module learning outcomes

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

Nanoscale

  • Discuss some of the motivations, benefits and challenges which arise when the dimensions of structures become <100nm.
  • Describe the role and significance of crystalline surfaces and interfaces in nanostructures. Explain the use and merits of electrons to probe surfaces.
  • Explain, and have some quantitative understanding of, some of the basic elastic and inelastic interactions of energetic electrons with solids.
  • Explain the principal operation of the SEM, and the physics, some quantitatively, underpinning the SEM.
  • Outline the advantages and limitations of SEM for surfaces and nanostructures analysis.
  • Explain the principal operation of the instruments and different imaging modes of STM and AFM, and the physics, some quantitatively, underpinning the STM and AFM.
  • Outline the advantages and limitations of STM & AFM for surfaces and nanostructures analysis.
  • Describe some applications of STM, AFM and SEM analysis to materials surfaces.
  • Discuss the use of spectroscopic techniques, Auger electron, electron energy loss, X-ray photoelectron spectroscopy, and X-ray microanalysis to study surfaces, their merits and limitations.
  • Explain why surface and nanoparticle properties can be significantly different to the bulk and in some cases in what way.
  • Describe the processes of interface formation and epitaxial growth at an atomistic level.
  • Explain the principal operation of the TEM and STEM, and the physics, some quantitatively, underpinning the TEM/STEM, and have some quantitative understanding of the imaging modes
  • Discuss the advantages and limitations of TEM/STEM for nanostructure analysis.
  • Describe some applications of TEM in the analysis of nanostructures.

Magnetism

Review the definitions and concepts of magnetism such as flux, flux density and field.

Understand and explain the fundamentals of magnetism and the magnetisation process:

  • The origins of diamagnetism, paramagnetism and ordered magnetism.
  • Concept of the demagnetising field and its role in magnetisation reversal processes.
  • Concept of magnetic anisotropy in terms of crystalline and shape effects and perpendicular anisotropy.
  • Formation of domains, domain walls and hysteresis in bulk materials.

Use these underpinning theories of magnetism to explain the magnetic behaviour and the applications of the following:

  • The origin and concept of single domain materials and reversal via the Stoner Wohlfarth mechanism.
  • Thin film magnetism and magnetic multilayers including methods of growth and techniques for measurement.
  • Hard and soft magnetic materials

Use the knowledge of magnetism and magnetic materials acquired to apply to key magnetic technologies:

  • Principles of magnetic recording in particular perpendicular media, Exchange Coupled Media, Heat Assisted Magnetic Recording, Microwave Assisted Magnetic Recording, Bit Patterned Media, the Read/Write Head.
  • Spintronics and applications: semi-classical free electron theory, classical magnetoresistance: Lorentz and anisotropic, spin-dependent transport: Giant Magnetoresistance, Tunneling Magnetoresistance, Magnetic Random Access Memories, Spin Transfer torque, Racetrack memory.

Module content

Please note, students who have not taken the prerequisites listed above must have taken an equivalent version of Thermodynamics and Solid State II and Mathematics II.

Syllabus

Analysing the Nanoscale

1. Introduction to nanotechnology

  • An overview of nanotechnology.
  • Several examples given to illustrate the broad nature of nanotechnology. The benefits and the challenges in materials and electronics as dimensions get smaller.

2. Fundamental & technological interest in surfaces and interfaces

  • Motivation for studying surfaces and interfaces. Relationship to nanotechnology.
  • Crystal surfaces, nanoparticles and their properties, microstructure.
    • Role of surfaces in heterogeneous interface formation. Ultra high vacuum

3. Sensitivity of different probes for nanoscale analysis of solid materials

  • Overview of limitations and advantages of different probes for nanoscale analysis: atoms, ions, photons, and electrons
  • Interaction and detection of scattered electrons from solids: elastic and inelastic mean free path, attenuation length, elastic scattering cross section, stopping power.

4. Spectroscopy

  • Spectroscopic techniques: electron spectroscopy, loss spectroscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy, x-ray microanalysis
  • Examples of applications

5. Imaging and analysing surfaces: the SEM

  • Scanning electron microscopy: principles of instrument, secondary electrons, backscattered electrons, imaging modes,
  • Interaction volume and dependence on incident electron energy.
  • Sampling volume and dependence of electron detection energy.
  • Limitations and advantages of SEM. Spatial resolution.
  • X-ray microanalysis in the SEM: principles, spatial resolution, thin-film analysis.
  • Examples of applications

6. Imaging and analysing surfaces: the STM

  • Scanning tunnelling microscopy: principles, imagine modes, true local probe for analysis of nanostructures with atomic resolution. Pros and cons.
  • Scanning tunnelling spectroscopy: relationship to local density of states.
  • Examples of application to semiconductor and metallic surfaces.

7. Imaging and analysing surfaces: the AFM

  • Principles of AFM: imaging modes: contact, intermittent and non-contact. Atomic resolution in non-contact modes. Discussion of other scanning probe techniques, e.g. magnetic force microscope, force probes
  • Examples of applications: insulator surface, biophysics

8. Imaging and analysing nanoparticles and interfaces: the TEM and STEM

  • Principles of TEM and STEM instruments: imaging modes, spectroscopy, specimen requirements
  • Limitations and advantages of TEM/STEM for nanostructure analysis, spatial resolution, aberration correction.
  • X-ray microanalysis in the TEM/STEM
  • Examples of applications

Magnetism

1. Origin and properties associated with diamagnetism and paramagnetism (both localised and of conduction electrons).

2. Ordered magnetism: ferromagnetism, antiferromagnetism and ferrimagnetism.  Curie-Weiss and Neel Laws, Weiss Molecular field, direct and indirect exchange interactions, band ferromagnetism.

3. The magnetisation process: hysteresis curves, domain theory, magnetostatic energy, demagnetising fields, magnetic anisotropy, domain walls.

4. Single Domain Particles, Stoner-Wohlfarth Model, applications of nanoparticles

5. Thin Film Magnetism and magnetic multilayers. Shape anisotropy, magnetostriction, perpendicular anisotropy, interlayer exchange coupling and exchange bias.

6. Thin film growth: epitaxial growth, Molecular Beam Epitaxy, Sputtering, Pulsed Laser Deposition, insitu characterisation: electron diffraction, Auger electron Spectroscopy and Quartz Crystal Monitors.

7. Magnetic Thin Film measurement: Vibrating Sample Magnetometer, Alternating Gradient Filed Magnetometer, X-Ray diffraction and reflection, neutron scattering, Magneto-Optic Kerr Effect, Magnetic Circular X-Ray Dichroism, Magnetic Force Microscopy, Lorentz Electron Microscopy.

8. Soft magnetic materials and their uses: design criteria and common materials e.g. SiFe, NiFe alloys, nanocrystalline and amorphous materials,

9. Hard magnetic materials and their uses: design criteria, BHmax and common materials: domain wall pinning, ferrites, AlNiCo, Rare-Earth transition metals.

10. Magnetic Data Storage: principles and challenges, perpendicular media, Exchange Coupled Media, Heat Assisted Magnetic Recording, Microwave Assisted Magnetic Recording, Bit Patterned Media, the Read/Write Head.

11. Spintronics and applications: semi-classical free electron theory, classical magnetoresistance: Lorentz and anisotropic; spin-dependent transport: Giant Magnetoresistance, Tunneling Magnetoresistance, Magnetic Random Access Memories, Spin Transfer torque, Racetrack memory.

Assessment

Task Length % of module mark
Essay/coursework
Magnetism Assignment
N/A 7
Essay/coursework
Nanoscale PPQs
N/A 7
University - closed examination
Nanoscale & Magnetism
3 hours 86

Special assessment rules

None

Reassessment

Task Length % of module mark
University - closed examination
Nanoscale & Magnetism
3 hours 86

Module feedback

Physics Practice Questions (PPQs) - You will receive the marked scripts via your pigeon holes. Feedback solutions will be provided on the VLE or by other equivalent means from your lecturer. As feedback solutions are provided, normally detailed comments will not be written on your returned work, although markers will indicate where you have lost marks or made mistakes. You should use your returned scripts in conjunction with the feedback solutions.

Exams - You will receive the marks for the individual exams from eVision. Detailed model answers will be provided on the internet. 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)

Blundell S: Magnetism in Condensed Matter (Oxford University Press)

Kittel C: Introduction to Solid State Physics (Wiley)

Peter J. Goodhew, John Humphreys, Richard Beanland: Electron microscopy and analysis. Taylor & Francis, 3rd edn. **

M Prutton: Introduction to Surface Physics. OUP **

Charles P. Poole, Jr., Frank J. Owens: Introduction to nanotechnology. Wiley.*

Ashcroft N W & Mermin N D: Solid state physics (Saunders College) **



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.