|
Calendar of Physics Talks Vienna
| Controlling diffusion and diffusion-induced phase transitions in epitaxial complex oxide thin films |
| Speaker: | Yingge Du (Physical Sciences Division, Pacific Northwest National Laboratory, USA) |
| Abstract: | Structurally ordered oxides exhibit a broad range of structural, compositional, and functional properties. As such, they have found widespread applications in microelectronics as well as energy storage and conversion, particularly for use as electrocatalysts, cathodes, and solid state ionics. However, as-designed materials can undergo dramatic property changes upon ion intercalation under their operating and/or extreme conditions, which may lead to performance degradation and device failure. This talk will highlight our recent effort aiming to modify complex oxides through controlled ion intercalation/extraction to achieve tunable functional properties. Combining in situ and environmental transmission electron microscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), synchrotron-based techniques, and ab initio simulations, we investigate the structural and chemical evolution |
| Date: | Mon, 22.01.2024 |
| Time: | 11:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Fachgruppenraum Physik |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Surface-Sensitive Studies of the Electrolyte-Electrode Interface |
| Speaker: | Edvin Lundgren (Lund University, Sweden) |
| Abstract: | The electrified electrode-electrolyte interface is notoriously difficult to study during electrochemical (EC) reactions. Most traditional surface science techniques are disqualified due to using electrons; on the other hand, several new in-situ experimental methods have been developed recently. Examples are Electro Chemical X-ray Photoelectron Spectroscopy (ECXPS), Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM), High Energy Surface X-Ray Diffraction (HESXRD) [1], and EC-IRAS [2]. However, each of these methods has limitations in the EC environment. A combination of methods is necessary to understand the electrode surface development and dynamics during EC reactions. |
| Date: | Mon, 22.01.2024 |
| Time: | 17:00 |
| Location: | Uni Wien, Kolingasse 14-16, Seminar Room 9 |
| Contact: | Mag. Stefan Uttenthaler |
| Applications of holographic QCD and the role of anomalous symmetries (Vienna Theory Lunch Seminar) |
| Speaker: | Jonas Mager (TU Wien) |
| Abstract: |
This talk will present applications of holographic models of QCD to interesting processes in hadron physics. In some way or another most of these processes involve anomalous symmetries. Holographic models of QCD are often particularly good at reproducing the symmetries of the dual theory and their anomalies, hence the predictions for these observables are of special interest. In particular, I will show different ways the U(1)_A anomaly can be realised in holographic models and subsequently broken by quark masses, during which we will encounter interesting concepts such as superconnections and tachyon condensation. I will present numerical results for observables, such as hadronic light by light scattering, double photon decay of mesons and [...]
[[part of the "Vienna Theory Lunch Seminar, see https://lunch-seminar.univie.ac.at ]] |
| Date: | Tue, 23.01.2024 |
| Time: | 12:30 |
| Duration: | 75 min |
| Location: | TU Wien: Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room DB10E11 |
| Contact: | Florian Lindenbauer |
| A Combinatorial Derivation of the Standard Model Particles from the Dirac Lagrangian |
| Speaker: | Charlie Beil (University of Graz) |
| Abstract: | I will begin by introducing a modification to general relativity where time is stationary along the worldlines of fundamental particles. The aim of this new geometry is to describe certain quantum phenomena using (classical) spacetime metrics which are degenerate. For example, on such a spacetime the dimensions of tangent spaces vary, and spin wavefunction collapse is modeled by the projection from one tangent space to another. I will then describe how the free Dirac Lagrangian on such a spacetime yields the standard model particles.
Specifically, we obtain three generations of leptons and quarks, the electroweak gauge bosons, and the Higgs boson -- all with their correct spin, electric charge, and color charge -- together with precisely one new massive spin-2 boson. Finally, I will show how the trivalent interaction vertices arise from the combinatorics of the Dirac Lagrangian subject |
| Date: | Tue, 23.01.2024 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | TU Wien Freihaus, Wiedner Hauptstrasse 8, 3rd floor, yellow tower, Sem. R. DB gelb 03 |
| Contact: | S. Fredenhagen, D. Grumiller, T. Tran, A. Fiorucci |
| Computational Studies of the Fe3O4(001) Surface as a Model for Single-Atom Catalysts |
| Speaker: | Panukorn Sombut (TU Wien, Institut für Angewandte Physik) |
| Abstract: | Single-atom catalysts (SACs) represent a new frontier in heterogeneous catalysis due to their particular local environment, resulting in a unique electronic structure in comparison with traditional supported nanoparticle catalysts. While the hydroformylation reaction between alkenes and syngas (CO and H2) conventionally involves Rh-based complexes, there is growing evidence suggesting that SACs can selectively catalyze this reaction. In this study, we employed a combination of DFT and surface science techniques, including STM, TPD, and XPS to investigate the interaction of C2H4, CO, and H2 on Rh1-decorated Fe3O4(001). We explore the intricate details of how individual molecules interact with Rh adatom. We show that the local binding environment of the Rh1 adatom on the support also influences how molecules absorb. By unraveling these molecular interactions, we aim to contribute valuable |
| Date: | Tue, 23.01.2024 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Prof. Gareth Parkinson |
| A Comparative Study of Late-Transition Metal Single Atoms on Fe2O3(1102 ) |
| Speaker: | Ali Rafsanjani-Abbasi (TU Wien, Institut für Angewandte Physik) |
| Abstract: | Precious metals supported on oxides exhibit exceptional effectiveness in various chemical reactions, such as hydrogen evolution, water gas shift, photocatalytic processes, and CO-oxidation reactions due to their elevated activity and/or selectivity. Downsizing catalysts to single atoms enhances the efficiency, and so-called âsingle-atom catalysisâ is now an important field of research. Nevertheless, achieving stable single atoms of late-transition metals on oxide supports without compromising catalytic activity raises significant challenges. This seminar centers on surface science techniques to examine the specific binding environment of rhodium, platinum, and iridium adatoms on α-Fe2O3(11 Ì
02)-(1Ã1). Using STM and XPS, I will discuss the stability of single atoms at room temperature, their adsorption sites, and the impact of O2. Additionally, the sintering behavior of single atoms at el |
| Date: | Tue, 23.01.2024 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Prof. Gareth Parkinson |
| Photocurrents induced by structured terahertz radiation |
| Speaker: | Sergey Tarasenko (Ioffe Institute, St. Petersburg) |
| Abstract: | Structured radiation, such as twisted beams carrying orbital angular momentum, has a great potential for the use in optics and optoelectronics. Here, we explore the interaction of structured terahertz radiation with two-dimensional electron systems and show that the structured radiation can drive dc electric currents and currents at double frequency. The currents can be related to the spatial gradients of the intensity, Stokes polarization parameters, and phase of the electromagnetic field. We discuss the physics of such effects and the microscopic mechanisms of the current generation.
A.A. Gunyaga, M.V. Durnev, and S.A. Tarasenko, Photocurrents induced by structured light, Phys. Rev. B 108, 115402 (2023). |
| Date: | Tue, 23.01.2024 |
| Time: | 16:00 |
| Duration: | 45 min |
| Location: | Freihaus SR DA Grün 06B, https://tuw-maps.tuwien.ac.at/?q=DA06G10 |
| Contact: | Andrei Pimenov |
| Flavour Non-Universal Interactions |
| Speaker: | Gino Isidori (University of Zurich) |
| Abstract: | Flavour physics represents one of the most fascinating puzzles of particle physics.
I will discuss some recent developments in this field, both from a theoretical perspective and from a more phenomenological point of view. I will focus in particular on the idea of flavour non-universal gauge interactions as a way to address the origin of the flavour hierarchies, while enabling new physics at the TeV scale that can stabilise the electroweak sector. The implications of this class of models for various short- and medium-term flavour physics experiments, as well as for new-physics searches at high energies, will also be discussed.
|
| Date: | Tue, 23.01.2024 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura |
| Speaker: | Wan Cong (U of Vienna) |
| Abstract: | In a series of work, Aretakis, Czimek, and Rodnianski have studied the gluing of two sets of initial data to the Einstein equations along a null surface. By solving the linearized gluing problem around Minkowski and using the implicit function theorem, they have shown that two sets of C2 "sphere data" sufficiently close to Minkowski can be glued together along a null surface up to a ten dimensional obstruction space. In this talk, I will present a generalisation of this result to (i) higher dimensions, (ii) include the cosmological constant and (iii) the gluing of higher regularity Ck data.
Based on joint work with Piotr Chrusciel and Finnian Gray arXiv:2401.04442 [gr-qc] |
| Date: | Wed, 24.01.2024 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer Strasse 17, 2nd Floor |
| Contact: | P. Chrusciel |
| Spin waves for novel information systems |
| Speaker: | Andrii Chumak (University of Vienna) |
| Abstract: | A disturbance in the local magnetic order of a solid body can propagate in a magnetic material in the form of a spin wave (magnon). Among the key advantages offered by magnons for data processing are the scalability down to atomic dimensions, the compatibility with existing CMOS and spintronic technologies, the operations in the frequency range from GHz to hundreds of THz, the possibility to process data in the wide temperature range, and the access to pronounced nonlinear phenomena.
In my talk, after a general introduction to spin waves, I will address three research directions in which the spin waves and magnons offer particularly high potential: (1) magnon-based processing of Boolean data, (2) the potential of nanoscale spin-wave devices for 5G communication systems, and (3) the first steps towards quantum magnonics at mK temperatures.
|
| Date: | Wed, 24.01.2024 |
| Time: | 16:00 |
| Duration: | 45 min |
| Location: | Freihaus SR DC rot 07, https://tuw-maps.tuwien.ac.at/?q=DC07A15 |
| Contact: | Andrei Pimenov |
| Towards coherently driven spatially resolved electron spin resonance in a scanning electron microscope |
| Speaker: | Thomas Spielauer (TU Wien, Atominstitut) |
| Abstract: | Electron spin resonance is a widely used analytical tool in medicine, biology and material sciences. Spin systems have many applications in quantum physics - for example in quantum computing and sensing. Traditionally such spin systems are driven with microwaves which offer only limited spatial resolution. We are currently in the process of developing and building experiments with the aim to coherently drive electron spin systems with high spatial resolution using the collective effect of the non radiative near field of modulated electron beams. Since electron microscopes offer a well established and highly capable platform for electron beam experiments we want to integrate our experimental setup in a scanning electron microscope. This also opens up future possibilities to perform in-situ electron spin analysis in scanning electron microscopes.
In this talk I'm going to give a quick intr |
| Date: | Wed, 24.01.2024 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Fractons, Carroll, and flat space holography |
| Speaker: | Stefan Prohazka (University of Vienna) |
| Abstract: | Theories with exotic features, like restricted mobility, not only have
interesting connections to phenomenology and flat space holography but
also challenge common quantum field techniques. As a first step, we will
explore the consequences of conserved dipole symmetry and its connection
to fractons. Using the underlying symmetries we will then define
fractons and explain their correspondence to Carroll particles. We will
also discuss field theories with fracton and Carroll symmetry and
provide comments concerning novel infrared effects and relations to flat
space holography. |
| Date: | Thu, 25.01.2024 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, Seminar room on the 10th floor |
| Contact: | Iva Lovrekovic |
| Fast Quantum Interference of a Nanoparticle via Optical Potential Control |
| Speaker: | Nikolai Kiesel (Uni Wien) |
| Abstract: | Optical micromanipulation in the liquid phase has proven highly effective in achieving intricate control over the motion of nano- and microparticles. While optical traps in vacuum have gained increased attention in recent years for applications in force sensing, stochastic thermodynamics, and macroscopic quantum physics [1], the potential of optical tweezers for implementing spatiotemporal control and nonlinear optomechanics remains largely untapped. The extent to which such nonlinear approaches will enhance control over quantum states of mesoscopic systems is an open question, for two major reasons: On a technical level, due to the challenge of control in an ultra-low friction environment, and on a fundamental level due to the intrinsic measurement performed by the light field itself on the object's motion.I will argue for the feasibility of such experiments by discussing a specific exp |
| Date: | Fri, 26.01.2024 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Jörg Schmiedmayer |
|