The localization of the charge leads to a major change in the electrical resistance and the crystal structure of the Cs4O6 system.
Image source: Peter Jeglič and Denis Arčon
Publish Date: 03.12.2018
Category: Outstanding research achievements, Interdisciplinary research
Researchers at the Faculty of Mathematics and Physics at the University of Ljubljana and the Max Planck Institute in Dresden, Germany have discovered the charge ordering in a relatively simple crystal structure and thus opened new possibilities for the development of information technologies.
Authors: Denis Arčon, Peter Jeglič, Tilen Knaflič, Matej Komelj, P. Adler, M. Reehuis, M. Geiß, P. Merz, A. Hoser, A. Sans, J. Janek, M. Jansen, C. Felser
One of the first attempts to understand the charge dynamics of mixed valence systems was in 1939, when Evert Verwey, a Danish chemist, noticed a sudden leap in the resistance of magnetite at a temperature close to -150 °C. The research group from Slovenia, led by Prof Denis Arčon from the Faculty of Mathematics and Physics at the University of Ljubljana and Jožef Stefan Institute (Peter Jeglič PhD, Tilen Knaflič, Matej Komelj PhD) and the Max Planck Institute in Dresden, Germany (P. Adler PhD, M. Reehuis PhD, M. Geiß PhD, P. Merz PhD, A. Hoser PhD, A. Sans PhD, J. Janek PhD, Prof M. Jansen, and Prof C. Felser) reported in the Science Advances (journal’s impact factor 11.51) about a similar Verwey transition in a completely different system consisting of negatively charged oxygen molecules. The researchers found that the Cs4O6 transitions through a state in which all oxygen units O2x- have the same structure because of the rapid charge hopping between oxygen units into a new state in which the charge is localized and forms well-defined superoxide O2- and peroxide O22- anions.
The breakthrough of this study lies in the fact that researchers discovered charge ordering in a relatively simple structure where new physical phenomena are expected due to the coupling between different degrees of freedom characteristic of negatively charged oxygen molecules. In the future, its findings may be practically used in the field of information technology.
The work has already received echoes in the professional community, since Prof Denis Arčon had several lectures abroad on this subject in 2018.
Reference: Adler P., Jeglič P., Reehuis M., Geiß M., Merz P., Knaflič T., Komelj M., Hoser A., Sans A., Janek J., Arčon D., Jansen M., Felser C. Verwey-type charge ordering transition in an open-shell p-electron compound, Sci. Adv., 1 (2018), EAAP7581.