An Individual Postgraduate Study Package (IPSP) is a schedule of training, self-study, and other activities selected for each Postgraduate Research Student (PGR) in order to develop the research skills and background knowledge required by their area of study. It will guide PGRs through their training program in the first year of study and prepare them for independent research.
A good IPSP commences with a brief description of the student and the project. Its main content is a plan including a detailed description of activities/actions intended. It should include a 'Training Section' and a 'Project-Specific Study'. All entries should include an estimate of the study time expected and describe the mode of delivery. This indicates how the proposed learning is to be achieved and monitored, e.g. tutorials with supervisor; activities within research group, weekly reports, etc..
This will include all the activities required by the postgraduate training programme and selected courses from the University's Effective Researcher Development Programme (ERDP)
This will comprise a number of subsections specifying at least 100 hours of study for the student, e.g. 'background literature' or 'personal development', showing different types of training/study.
The Project-Specific Study will normally involve a significant amount of directed reading:
Personal Development Is an essential part of postgraduate training. This can be implemented through different routes, e.g.
Courses offered by external organisations or other departments within the University
Information may be stored on optical disks and within random access memory (RAM) chips by heating the storage medium, usually a chalcogenide alloy such as Ge2Sb2Te5 (GST), so that it undergoes a phase transition between amorphous and crystalline states which have different reflectance and electrical resistivity. However, our understanding of this phase transition is surprisingly limited. A recent study revealed that the material does not necessarily melt in a conventional sense, and suggested that optical excitation of specific electronic states drives a non-thermal phase transition. In phase-change RAM (PCRAM or 'Ovonic' memory), when a write pulse is supplied to the amorphous material, 'threshold switching' to a low conductivity state is observed before the structural phase change, or 'memory switching', occurs. The origin of the threshold switching mechanism remains controversial and the intrinsic timescales for threshold switching have never been measured. You will use time-resolved femtosecond optical measurement techniques to investigate the phase transition in GST and other chalcogenide alloys and use tailored optical pulses for more efficient writing and erasure. You will also examine the response of the alloy to the polarization of the optical pulse, since the observation of optically induced birefringence may provide a better understanding of the non-thermal nature of the transition. Finally you will perform time resolved optical and electrical measurements upon prototype PCRAM cells to understand the dynamics of threshold and memory switching processes in real devices. You will work closely with researchers from Engineering who are developing numerical models of the phase change process as part of an EPSRC funded collaboration.
Training will be provided through the Research Student Training Programme, details of which may be found at: http://newton.ex.ac.uk/handbook/PG-FirstArrival.html, and by attendance of the university's Effective Researcher Development Programme (ERDP).
Training relating specifically to your project is described below.
Beyond the standard training given to all students, you will also be advised on the hazards associated with working with ultrafast laser systems. You will be expected to read and understand the local rules governing the use of lasers within the research group and sign the sheet within the laser lab to signify your acceptance of these rules.
You will be expected to participate in the weekly Magnetic Materials group meeting held on Thursday at 1 pm. You will present a summary of your week and new results of interest on the data projector, and be involved in the discussion of results obtained by others. You will also be expected to give longer presentations within group meetings periodically; to make a presentation to the School at the beginning of your second year, and to put together a poster and you will give oral presentations at both UK and international meetings as your research progresses. Finally, you will participate in the Magnetic Materials group journal club at 9am on a Monday, where you will lead the discussion of recent papers from the literature that is relevant to your project.
Bonding in solids and the relationship to crystal structure; structural phase transitions; phonons in crystals; consideration of which phonons may be optically active.
The electronic structure of solids: methods for calculating band structure; interpretation of a band structure diagram; and the Fermi surface. Electrical transport in metals and semiconductors.
The principles of operation of ultrafast optical oscillators, regenerative amplifiers, optical parametric amplifiers and oscillators. The effects of group velocity dispersion upon pulse width, the use of prisms and gratings for pulse width correction, and pulse width measurement techniques.
Polarisation effects in linear optics: Jones matrices, Stokes parameters and the Poincare sphere; principles of operation of birefringent optical components and electro-optic devices; the Faraday and magneto-optical Kerr effects.
Non-linear optics: second harmonic generation and optical rectification; the non-linear Kerr and Faraday effects.
Phase change process in chalcogenide glasses; the nature of the liquid, amorphous and crystalline phases; processes of crystallization. The special case of GST; the 'umbrella flip'; resonant bonding; the 'treasure map'.
Optical properties of phase change materials; the reflectance spectrum and identification of direct optical transitions; origin of large optical contrast between amorphous and crystalline phases; Raman active modes.
Electrical properties of phase change materials; threshold and memory switching; apparatus for high frequency electrical measurements.
Phase change technology. Optical disk recording; anatomy of the disk drive system; methods of enhancing data storage density. Phase change RAM; nano-pillar and lateral architectures.
The individual study package will require the reading of books and journal papers. Notes will be kept and a written summary will be required for each section of the package. These will be drawn together in order to produce the first year literature review. The reports will be discussed at a weekly meeting between student and supervisor. Group meetings, journal club and attendance at national meetings will also aid the accumulation of subject specific knowledge.