Each year the Springer Thesis prize is awarded to a PhD work in order to recognise its scientific impact. The thesis of Philippe Tückmantel entitled “Scanning Probe Studies of Structural and Functional Properties of Ferroelectric Domains and Domain Walls”, supervised by Professor Patrycja Paruch was recognised by a Springer Theses prize and published in the Springer Theses series. It brings together a selection of the very best PhD theses from around the world and across the physical sciences.
Ferroelectric materials can form polarisation domains, separated by so-called domain walls, and re-orientable under an appropriate driving force. These materials are ubiquitously used as capacitors, infrared sensors, and in technologies such as ultrasound diagnostics. They are also promising for novel electronic devices and extremely useful as toy systems to test theories exploring fundamental aspects of interface physics.
For instance, domain walls can be locally conducting, and, since they can easily be created and moved around, this conductivity opens the way to reconfigurable electronic circuits and low-power memories. However, the exact nature of the conduction mechanisms can be elusive. In his doctoral thesis, Philippe Tückmantel studied links between local distortions of the domain walls and variations in the domain wall conductivity, shedding more light on how nanoscopic materials defects affect the domain wall geometry and its properties.
Ferroeletric domains are also a great tool to study so-called universal behaviour. A wide variety of systems, from earthquakes to the evolution of stock market prices can often be described by the same type of statistical equation. In other words, the behaviour of one system can under certain circumstances be directly translated to another, possibly more accessible one. But determining these circumstances is a crucial and complex endeavour. By combining nanoscale experimental observations ferroelectric domain growth with statistical analyses for the first time, Philippe and his coworkers show that the statistical equation describing the domains’ characteristic avalanche-like growth behaviour is modified when the electrical force applied to promote domain growth goes above a certain level. This important result highlights how crucial the probing force is for understanding these laboratory-level systems before general comparisons can be made more broadly to other systems.