Project:

ESR-11: PhD at the University Cambridge, UK

Topic:

Domain wall dynamics and neuronic ‘crackling noise’

Supervisor:

Prof. dr. Ekhard Salje

Co-supervisor:

Prof. dr. Michael Carpenter

Non-academic Supervisor:

Dr. Stephan Tiedke (aixACCT Systems GmbH, Germany)

Domain wall dynamics and neuronic ‘crackling noise’

The project is focused on the analysis of ferroelastic and ferroelectric oxides with high concentrations of domain walls. These domain walls under strain fields but also under electric and magnetic fields. Movements under electric fields occur also in non-polar bulk materials because the domain walls contain the polarity as part of the internal domain wall structure. Typical examples are CaTiO3, SrTiO3, SnTe, KMnF3 etc. When the movement is a-thermal (not thermally activated) we observe wall movements close to the dynamics of neuron networks. This includes power-law distributed energies, long waiting times between events and specific distributions for the duration of events. Experimental results will be obtained in Cambridge (optical, RUS and RPS spectroscopy) and via a worldwide consortium with laboratories including China and France. The main part of the research will be performed at Cambridge University, United Kingdom, Department of Earth Sciences. Additionally, the ESR will spent time the Bernoulli Institute for Mathematics, Computer Science and Artificial Intelligence, University of Groningen, the Netherlands for the simulation of networks (1 Month) and at aixACCT Systems GmbH, Germany for Electrical measurements for RUS (1 Month). During the project it is foreseen that the ESR will also spend time in some of these laboratories and Zurich, Lausanne and Dresden, depending on progress. TEM analysis is planned in collaboration with at CSIC in Zaragoza, Spain.

The University of Cambridge is located north of London with easy access to the capital. It has an excellent academic program where research is undertaken jointly between departments. The cultural environment is excellent. Cambridge has been in operation for 800 years and houses ~12000 undergraduate students and ~ 4000 PhD and ~ 3000 postdoctoral workers. Cambridge is top-ranked in almost all disciplines.

The department of Earth Sciences works in a very large field from geophysics to classic geology. Many projects are undertaken jointly with the department of material sciences, physics and chemistry. The field of avalanche physics, crackling noise and Barkhausen noise was largely generated in this department. Avalanches are key to Earth Quakes and geological events such as the collapse of coalmines etc. Ferroeleasticity was researched here since 1985 and many of the key results were obtained during the last 10 years. Recently we expanded our research to magnetic systems and computer simulation of the dynamics of ferroelastic domain walls.

Our web-site is
https://www.esc.cam.ac.uk
The supervisors are M.A. Carpenter (https://www.esc.cam.ac.uk/directory/michael-carpenter)
and E.K.H. Salje (https://www.esc.cam.ac.uk/directory/ekhard-salje).

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