The Peter-Haasen Prize is awarded for an outstanding PhD thesis in the
area of materials science! This year's winner is Dr. M. Möller. After the prize ceremony, Dr. Möller will give a presentation about his work:
Title: Of magnets and defects: Imaging vortex pinning and gyration by time-resolved and in-situ Lorentz microscopy.
Abstract: In the realm of materials science and nanotechnology, Ultrafast Transmission Electron Microscopy (UTEM) emerges as a cutting-edge investigative tool, providing unprecedented spatio-temporal resolution to investigate dynamical processes of materials at the nanoscale. Leveraging UTEM's unique capabilities, the thesis explores its application for the study of current-driven magnetization dynamics. Employing Lorentz microscopy, Dr. Möller investigates the time-resolved gyration of a magnetic vortex confined within
a nanostructure. Achieving an unprecedented accuracy (±2 nm) in tracking the motion of the vortex core reveals minute deviations from an idealized path, hinting the presence of defects in the magnetic film. To reveal the origin of these defects, Dr. Möller combines bright-field imaging, time-resolved Lorentz microscopy and an additional novel
approach to actively probe static pinning sites within magnetic nanostructures and find grain boundaries to significantly contribute to vortex pinning in polycrystalline magnetic films.
Halide perovskite nanocrystals (NCs) have emerged as an intriguing material for optoelectronic applications, most notably for light-emitting diodes (LEDs), lasers, and solar cells. Despite impressive advances, halide perovskites have not yet been commercialized due to certain inherent limitations. Importantly, they are highly prone to environmentally induced degradation, incorporating lead can be problematic, and not all compositions perform equally.
In this talk, I will briefly introduce the history, structure, and physics of halide perovskites and their potential employment for optoelectronics. I will specifically explore our recent results on tailoring halide perovskite nanocrystals to improve their stability and performance in underachieving spectral regions. By merging chemical synthesis, optical spectroscopy, and device fabrication, we have created a strong feedback loop, which can lead to the rapid improvement of halide perovskite materials. I will explain how we merge different novel techniques to understand the complex interplay between morphology, composition, and halide perovskite nanocrystals' resulting optical and optoelectronic properties. I will conclude with a brief analysis of the potential and outlook for commercialization of halide perovskites.
Understanding the physical principles that are used by living cells and organisms to perform their amazingly complex task is one of the holy grails that biophysics aims for. Despite the powerful toolboxes provided by physics in the form of experimental quantitative methods and theoretical models, the sheer complexity of living systems makes a clean description very challenging. One main problem is that the framework of statistical mechanics cannot be easily used in the non-equilibrium and continuously energy-consuming environments represented by living organisms. I will explain the problem by a case study of red blood cell membrane flickering. This motion of the most abundant cell of our blood was discovered about 130 years ago. During the past hundred years, an extensive and sometimes even emotional scientific debate unfolded in the quest to explain the nature of this erratic movement. Is it simply Brownian motion, or a sign of “live” that is driven by metabolic energy conversion? Using non-equilibrium physics approaches, we were able to solve the mystery. The methods that we developed to study red blood cells have been the starting point for a full set of new experimental and theoretical approaches to study the physics of living systems in general.
The expansion rate of our universe, the "Hubble rate", is one
of the key observables in big bang Cosmology. It has been measured to a
precision of 1.4% and it can be predicted using Einstein's equation in
General Relativity. The prediction requires knowledge of the dominant
energy densities in the universe. In our Standard (LCDM) Model of the
universe these energy densities are ordinary matter, dark matter, and
dark energy, and their abundance is well-determined thanks to precision
measurements of the Cosmic Microwave Background radiation and the large
scale distribution of matter. The "trouble with Hubble" is that the state
of the art prediction disagrees with observations at the 5 sigma level.
In this colloquium, we will review the two disagreeing
determinations of the Hubble rate and conclude that a fundamental change
of the LCDM model may be required. I will speculate that the evidence
points towards an undetected dark radiation component in our universe.
