Chemistry offers almost unlimited possibilities. There are countless ways of combining elements into new substances, and time and again new substances exhibit as yet unknown properties. One aspect in which physicists have more than a passing interest is the innumerable combinations of different metals with oxygen or other non-metals, where exotic quantum effects occur. Scientists at the Max Planck POSTECH Center for Complex Phase Materials investigate precisely these materials.
These compounds often exhibit different properties if researchers change the temperature, applied pressure, magnetic and/or electric fields or the way the light is placed. These dependencies are reflected in comprehensive – and thus very complex - phase diagrams which describe the respective state of a matter under certain conditions, such as a certain pressure or temperature.
The researchers working with Liu Hao Tjeng, Director at the Max Planck Institute for Chemical Physics of Solids in Dresden, and Jae-Hoon Park, Professor at POSTECH University in Pohang, Korea are not only looking for ways to produce materials in each case with the desired composition in as pure a form as possible; they also undertake extensive analyses of their properties and develop models to explain them. The Max Planck Institute for Solid State Research and scientists from leading research organizations in Taiwan are also involved.
Crucial for the properties of these complex phases is the behaviour of the electrons, which often do not move independently of each other, but have a strong dependence on one another. To explain and predict this behaviour with physical models, which are expressed in equations, is the focus of the scientific cooperation. Only when physicists can accomplish this for exotic effects as well, will they have a comprehensive understanding of the properties of matter. And only then will they be able to provide information about which of all the possible chemical compounds might be interesting for applications, such as superconductors - or possibly even for applications that have yet to be imagined.
Picture: Entrance of the Pohang University of Science & Technology, in the background Jae-Hoon Park, one of the Leaders of the Max Planck-POSTECH Center for Complex Phase Materials. © dpa/MPG