Allgemeines Physikalisches Kolloquium
im WS 2023/24
Donnerstag, 16 Uhr c.t. Ort: HS 2, IG 1, Wilhelm-Klemm-Str. 10, 48149 Münster
09.11.2023 Prof. Michel Janssen
Reflections on Oppenheimer, the man and the movieChristopher Nolan's movie Oppenheimer raises a number of interesting questions about the life and times of its main subject and offers a range of answers for viewers to choose from. Why was Oppenheimer in favor of dropping atomic bombs on Hiroshima and Nagasaki? Why did he not become a spokesperson for those among his fellow physicists opposed to their military use? And why then was he adamantly opposed a few years later to the development of the hydrogen bomb? What about his communist sympathies? How could the same derogatory information that was well known when he was cleared to become the head of the General Advisory Committee to the Atomic Energy Commission in 1947 be used so effectively to revoke his security clearance in 1954? Like Martin Sherwin and Kai Bird, the authors of the book on which the movie is based, I will deal with these questions as they come up as Oppenheimer's life and career unfolds, from US ambassador of quantum mechanics in Berkeley to scientific leader of the Manhattan project in Los Alamos to Einstein's boss at the Institute of Advanced Studies in Princeton and prominent adviser to the Truman administration on matters concerning nuclear physics and national security to his fall from grace under Eisenhower and his eventual partial rehabilitation by Kennedy and Johnson. I will highlight the roles of those individuals in Oppenheimer's life who play a major role in the movie, especially his nemesis, Lewis Strauss.
16.11.2023 Dr. Dima Afanasiev
Light-driven ultrafast magnetismFor centuries, the central goal of condensed matter physics has been to understand and describe naturally occurring phenomena, both in macroscopic and microscopic terms. Over the past few decades, a new paradigm has emerged: to experimentally realize and control new states of matter that are not found in nature. In addition to answering fundamental scientific questions, the control and knowledge of potential 'exotic' phases also hold the promise of creating a new and radically different generation of functional devices.Ultrashort pulses of light are particularly appealing in this context as they allow us to create strongly nonequilibrium transient states of matter with properties that are often not even attainable in equilibrium. Some examples include light-induced superconductivity, metal-to-insulator transitions, and light-driven Floquet engineering. In this discussion, I will explore how light can be used to control magnetism, encompassing fundamental magnetic interactions, magnetic phase transitions, and highly nonlocal spin dynamics. I will particularly focus on nonthermal methods for controlling magnetism when the photon energy of light is precisely tuned in resonance with elementary excitations, such as lattice vibrations, orbitals, or electron excitations, which have a direct impact on the ordered spins.
23.11.2023 Dr. Otakar Frank
(Nano)spectroscopic signatures of intricate relations between 2D layers and their substrateCommon spectroscopic investigation of two-dimensional materials and their van der Waals (vdW) heterostructures mostly relies either on diffraction-limited microRaman or photoluminescence (PL). However, these methods do not properly capture local variations caused by, e.g., nanometre-sized heterogeneities stemming from contamination trapped between the layers or complex strain and charge patterns formed by strong out-of-plane interactions.Tip-enhanced spectroscopy methods enable the access to information on the local lattice deformation and also on the interaction between the individual layers composing the heterostructure. What may appear as peak splitting in micro-Raman or PL spectra of transition metal dichalcogenides (TMDC) on metal substrates or of vdW heterobilayers, can, in fact, often come from mixing up signals from various regions within the laser spot, including new or discretely shifted peaks. In other cases, however, peak splitting can indicate lifting the degeneracy of the phonon, due to, for example, uniaxial deformation. Spectroscopic fingerprints, both on micro- and nanoscale, of variously interacting vdW layers will be discussed, including TMDCs on metals [1-3] and TMDC heterobilayers [4-6].References: Vilecký et al., Phys. Chem Lett. 11, 6112 (2020) Vilecký et al., Adv. Mater. Interfaces 7, 2001324 (2020) Rodriguez et al., Phys. Rev. B 105, 195413 (2022) Rodriguez et al., 2D Mater. 8, 025028 (2021) Rodriguez et al., J. Phys. Chem. Lett. 13, 5854 (2022) Rodriguez et al., ACS Nano 17, 7787 (2023)
30.11.2023 Prof. Eva Blasco / Prof. Martin van Hecke
Bitte beachten: Dieses besondere Kolloquium wird vom CRC Intelligent Matter organisiert, deshalb findet es zu ungewohnter Zeit ( 15 Uhr s.t.) und an einem unüblichen Ort (Center for Soft Nano Science SON) statt.
Link zur Vortragsankündigung auf der Webside des CRC 1459 Intelligent Matter
Prof. Eva Blasco "Designing Intelligent Materials for 4D (Micro)Printing"
Prof. Martin Van Hecke "Emergent Computing in Mechanical Metamaterials"
07.12.2023 Prof. Sven-Olaf Moch
The proton structure in the LHC era
We review the status and precision of parton distribution functions (PDFs), the strong coupling and the heavy quark masses in global fits to next-to-next-to-leading order (NNLO) in QCD.
We discuss the impact of data from the LHC as well as the combined data from for inclusive deep-inelastic scattering.
We illustrate how the precision of available experimental data challenges current theoretical predictions and we outline areas for future improvements.
14.12.2023 Prof. D. Wegner
Quantum simulator to emulate lower dimensional molecular structureDesigning materials with tailored physical and chemical properties requires a quantitative understanding of interacting quantum systems. In order to provide predictability, a promising route is to create bottom-up platforms, where the electronic properties of individual and interacting atoms can be emulated in a tunable manner. Here, we present a solid state quantum simulator based solely on patterned Cs atoms on the surface of semiconducting InSb(110). We use this platform to locally bind electrons in traps that emulate artificial atoms, by precisely positioning Cs atoms with the tip of a scanning tunneling microscope (STM). The bound localized states are probed and mapped via scanning tunneling spectroscopy (STS). These artificial atoms serve as building blocks to realize artificial molecular structures with different orbital symmetries. We find bonding and anti-bonding states for coupled dimers of artificial atoms and orbitals of higher symmetries (π orbitals) for a linear assembly of a few artificial atoms. Based on these artificial orbitals and various atomic patterns, we emulate the structure and orbital landscape of well-known planar organic molecules, including antiaromatic molecules. Presented results validate this new quantum simulator platform and prove its high tunability. I will provide an outlook toward a many-body quantum simulator.
11.01.2024 Prof. Yvonne Wong
18.01.2024 Prof. Ralph Engel
25.01.2024 Prof. Hendrik Bentmann
01.02.2024 Prof. Toeno Van der Sar