Description

This module covers areas of physics that emerged as a result of application of the state-of-the-art ultrafast measurement techniques in the study of spintronics, magnonics and metamaterials. In particular, topics explored in this module include ultrafast sources, time resolved spectroscopy and imaging, ultrafast magnetisation reversal, excitation of non-Fermi electron distributions, coherent phonons, magnons, etc., ultrafast demagnetisation, nonlinear electro- and magneto-optical effects (including electromagnetic radiation).

Module Aims

Ultrafast physics is revolutionising our understanding of matter and offering many new exciting opportunities, for example some speculate that table-top particle accelerators might become possible. This module aims to give the student in-depth understanding of the non-equilibrium phenomena observed in condensed matter samples that have been excited by ultrafast optical pulses.

Intended Learning Outcomes (ILOs)

A student who has passed this module should be able to:

• Module Specific Skills and Knowledge:
  1. describe and explain the principles of operation of ultrafast lasers and amplifiers;
  2. describe and explain the time domain hierarchy of ultrafast processes in various solid state materials;
  3. give clear and technically detailed explanations and sketch diagrams of a range of ultrafast measurement techniques;
  4. predict the types of information that the different ultrafast measurement techniques can yield from samples with various electrical and magnetic properties and understand the limitations inherent to the techniques;
  5. interpret ultrafast measurements in solid state samples in terms of the main dynamical processes triggered by ultrafast optical pulses;
  6. apply the Landau – Lifshitz equations and three temperatures model to problems of ultrafast physics;
  7. describe and explain the concept of metamaterials;
• Discipline Specific Skills and Knowledge:
  8. select an ultrafast measurement technique appropriate for characterisation of dynamic properties of specific solid state samples;
  9. apply the fundamentals of electromagnetism and condensed matter physics to design of novel measurement techniques and to interpretation of state-of-the-art experimental results;
  10. analyse limitations imposed upon the laws of core physics derived in equilibrium by ultrafast measurements of non-equilibrium solid state phenomena;
• Personal and Key Transferable / Employment Skills and Knowledge:
  11. engage with new knowledge that surpasses or seemingly contradicts accepted views;
  12. retrieve and evaluate information from specialist research literature.

Syllabus Plan

1. Revision
   1. Maxwell's Equations for the electromagnetic field, constitutive equations, electromagnetic waves
   2. Electronic band theory and its relation to optical properties
   3. Classification of materials according to their electric and magnetic properties
2. Ultrafast Lasers and Amplifiers
   1. Absorption, spontaneous and stimulated emission, Einstein coefficients
   2. Three- and four-level systems
   3. Amplification and lasing — population inversion, optical gain and feedback
   4. Cavities and cavity modes
3. Ultrafast Measurement Mechniques
   1. Principles of pump-probe measurements
   2. All-optical time resolved techniques
   3. Magneto-optics
   4. Time-resolved measurements
   5. Measurement of magnetisation dynamics
   6. Time-resolved microscopy and spectroscopy
4. Ultrafast Processes in Solids
   1. Ultrafast electron-dynamics
   2. Ultrafast lattice dynamics and coherent phonons
   3. Two-temperature model
5. High Frequency and Ultrafast Processes in Magnetically Ordered Materials
   1. Einstein-de Haas experiment and origin of magnetism
   2. Larmor precession and equation of motion of the magnetisation (torque equation)
   3. Exchange spin waves, magnetic heat capacity and temperature dependence of the magnetisation
   4. Phenomenological description of magnetisation dynamics in ferromagnets, magnetic energies, effective magentic field and the Landau-Lifshitz equation
   5. Relaxation of magnetisation dynamics
   6. Three-temperature models of electron, lattice and spin dynamics in metallic ferromagnets
   7. Ultrafast demagnetisation
   8. Optical excitation and coherent control of spin waves in metals and dielectrics
6. Metamaterials
   1. Conceptual framework
   2. Basic properties and designs of metamaterials
   3. Magnonic metamaterials and applications

Learning and Teaching

Learning Activities and Teaching Methods

Assessment

Resources

The following list is offered as an indication of the type & level of information that students are expected to consult. Further guidance will be provided by the Module Instructor(s).

Core text:

• Not applicable

Supplementary texts:

• Diels J.C. and Rudolph W. (2006), Ultrashort Laser Pulse Phenomena (2^nd edition), Academic Press, ISBN 978-0-122-15493-5 (UL: 621.366 DIE)
• S. Maekawa, S.O. Valenzuela, E. Saitoh and T. Kimura (Eds) (2012), Spin Current, Oxford University Press, ISBN 978-0-19-960038-0 (UL: 621.381 MAE)
• Miller A., Reid D.T. and Finlayson D.M. (Eds) (2004), Ultrafast Photonics, Taylor and Francis, ISBN 978-0-750-30904-2 (UL: 621.3827 MIL)
• R. Skomski (2008), Simple Models of Magnetism, Oxford University Press, ISBN 978--0-19-857075-2 (UL: Online)

ELE:

• http://newton.ex.ac.uk/redirects/ELE/phy3069

Further Information

Prior Knowledge Requirements

Re-assessment

Re-assessment is not available except when required by referral or deferral.

Notes: See Physics Assessment Conventions.

KIS Data Summary

Miscellaneous