BESSY II: Experimental verification of an exotic quantum phase in Au2Pb
The figure shows the measured energy-momentum relationship for Au2Pb. The linear behavior is evidence for a Dirac semimetal. In addition, a Lifshitz transition is observed: At temperatures 223 K and below, the electrons behave like positively charged particles, whereas at room temperature they behave like negatively charged ones. © HZB
A team of HZB has investigated the electronic structure of Au2Pb at BESSY II by angle-resolved photoemission spectroscopy across a wide temperature range: The results are in accordance with the electronic structure of a three-dimensional topological Dirac semimetal, in agreement with theoretical calculations.
The experimental data unveil some very special features linked to a Lifshitz transition. The study broadens the range of currently known materials exhibiting three-dimensional Dirac phases, and the observed Lifshitz transition demonstrates a viable mechanism to switch the charge carrier type in electric transport without the need for external doping. Moreover, the material becomes interesting as candidate for the realization of a topological superconductor.
The study which includes theory from San Sebastian and synthesis from Princeton was highlighted as Editor's Suggestion in the journal Physical Review Letters.
- Hydrogen storage in MXene: It all depends on diffusion processesTwo-dimensional (2D) materials such as MXene are of great interest for hydrogen storage. An expert from HZB has investigated the diffusion of hydrogen in MXene using density functional theory. This modelling provides valuable insights into the key diffusion mechanisms and hydrogen's interaction with Ti₃C₂ MXene, offering a solid foundation for further experimental research.
- Research up close! The Long Night of Science at HZBOn 28 June, it's that time again: the Long Night of Science will take place from 5 pm to midnight in Berlin and also in Adlershof! Come around and take a look behind the scenes of our exciting research.
- HZB and National University Kyiv-Mohyla Academy start cooperation in Energy and ClimateHelmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB) and the National University of "Kyiv-Mohyla Academy" (NaUKMA) have signed a Memorandum of Understanding (MoU). The MoU serves as the starting point for collaborative research, academic exchange, and capacity-building between the two institutions. Actions will be taken to establish the Joint Research and Policy Laboratory at NaUKMA in Kyiv. The aim of the future laboratory is to jointly develop research and policy analysis, focusing on the energy and climate dimensions of Ukraine’s EU integration.