Jahresübersicht für das Jahr 2020
06 Jan 2020
Seminar für Kern- und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie |
| Dr. Nadine Chiera, PSI, Schweiz | |
Chemical investigation of exotic radionuclides | |
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Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |
| Niklas Schmitt, University of Mainz | |
Suche nach dunkler Energie in Monojet-Ereignissen bei 13TeV mithilfe des ATLAS-Detektors am LHC | |
Bachelorkolloqium |
07 Jan 2020
Physikalisches Kolloquium
Institut für Kernphysik, Johann Joachim Becher Weg 45 16:00 Uhr s.t., HS KPH |
| Professor Christian Enss , Kirchhoff Institute for Physics, Heidelberg | |
Small, Cold and Universal: Cryogenic Micro-Calorimeters a New Key Technology | |
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08 Jan 2020
PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |
| Cristina Lazzeroni, University Birmingham, UK | |
The decay K+→π+vv ̅, with a very precisely predicted branching ratio of less than 10-10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+→π+vv ̅ with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv ̅, entering the domain of 10-10 single event sensitivity and showing the proof of principle of the experiment. Thanks to the statistics collected in 2017, NA62 surpasses the present best sensitivity. The preliminary result from the 2017 data set is presented. The general status of the experiment, including other recent measurements, are presented. Plans for the next data taking and for a longer term future are also discussed.
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09 Jan 2020
Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7 |
| Jun.-Prof. Dr. Jamir Marino, Institut für Physik, Universität Mainz | |
The talk will discuss instances of dynamical phases of interacting quantum many body models where coherent and dissipative dynamics occur on equal footing, shaping novel non-equilibrium phase diagrams. The first part of the talk will discuss long-range interacting quantum simulators where an external periodically driven field can stabilise phases without equilibrium counterpart against instabilities triggered by many body quantum fluctuations. In the second part, I will present an instance of ‘cold' time crystal occurring in open quantum systems, where neither MBL or pre-thermalisation are required to stabilise a strongly interacting non-equilibrium steady state. Time permitting, I will advertise some novel results on a purely dissipative analogue of long-range interacting quantum simulators, which can be implemented in quantum optics or solid state platforms. | |
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13 Jan 2020
Seminar für Kern- und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie |
| Dr. Marine Vandebrouck, CEA Saclay | |
243Es, 249Md: from production cross-sections measurement to spectroscopy - Perspectives at GANIL-SPIRAL2/S3 | |
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Theoriekolloquium
Die Dozierenden der Theoretischen Physik Sonderseminar: 14:00 Uhr s.t., Medienraum, Staudinger Weg 7, 03-431 |
| Prof. James Freericks, Georgetown University, USA | |
Quantum mechanics was created with the matrix mechanics of Heisenberg, Born, and Jordan. Schroedingers wave mechanics shortly followed and allowed for simpler and more powerful calculations. Both Pauli and Dirac introduced a formulation of quantum mechanics based on operators and commutation relations, but it was never fully developed in the 1920s. Instead, Schroedinger formulated the operator approach with his factorization method, which later was adopted by the high-energy community as supersymmetric quantum mechanics. In this talk, I will explain how one can formulate all of quantum mechanics algebraically by a proper use of the translation operator on top of Schroedingers factorization method. I will give examples of how one can compute spherical harmonics algebraically, how one can find harmonic oscillator wavefunctions, and will even describe an operator-based derivation of the wavefunctions of Hydrogen. I will end with a proposal for a novel way to teach quantum mechanics, focusing first on conceptual ideas related to superposition, projective measurements, and entanglement. Then developing more conventional topics like spin, harmonic oscillator, angular momentum, interacting spin models, central potentials, particles in a box and so on. This is the subject of a book in progress entitled Quantum Mechanics without Calculus. | |
Sonderseminar | |
Sondertermin/-raum Montag, 14:15 h im Medienraum, Staudinger Weg 7, 03-431 |
Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |
| Julian Fischer, Institut für Physik | |
Development of an EM trigger algorithm in the ATLAS forward region | |
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Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 10:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431 |
| Abhishek Erram , Indian Institute of Technology Kharagpur | |
In this work, we have made a polycrystalline sample of Dy2BaNiO5 by a standard solid-state reaction route. The formation of the compound was ascertained by x-ray powder diffraction pattern. The dc χ measurements were carried out in the temperature interval 5–300 K in the presence of magnetic fields of 100 Oe and 5 kOe for zero-field-cooled (zfc) and field-cooled (fc) conditions using (SQUID) and isothermal magnetization (M) behavior was studied at a certain selected low temperature. Then, Thin film of Dy2BaNiO5 certain thickness were deposited on Mgo , Al203 ,STO and LAO substrate by Pulsed Layer Deposition method these films were annealed at temperature 650 oC. Some of the samples were Characterized by X-ray diffraction (XRD). Magnetic behavior was also studied. Results show that of formation of thin film. Signs of magnetic behavior was also evident. | |
Sonderseminar | |
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15 Jan 2020
PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |
| Christian Fischer, Universität Gießen | |
In this talk I will give an overview on recent results on the spectrum and properties of conventional baryons and 'exotic' tetraquarks as obtained in the framework of Dyson-Schwinger and Bethe-Salpeter equations. I will discuss the spectrum of light baryons with focus on the comparison with quark model expectations, the impact of dynamical mass generation and the importance of relativistic components in the wave functions of baryons. I will also discuss extensions to SU(3).
For four-quark systems I will summarize results for light quarks and discuss recent progress on discriminating between tetraquark, molecule or hadro-quarkonium configurations in heavy-light systems.
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Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 10:30 Uhr s.t., QUANTUM Seminarraum (02-427), Institut für Physik, Staudingerweg 7 |
| Brian Rost and Lorenzo Del Re , Georgetown, USA | |
The driven dissipative many body problem is one of the longest standing unsolved problems in physics and it has experienced a renewed interest in the last decade. In fact, dissipation has been theoretically proposed as a resource for quantum computation and experimentally has been demonstrated that it can be employed to prepare maximally entangled states.
Thus, quantum computers could shed some light on the unsolved problem of driven-dissipative quantum systems but there are many choices for how one engineers the reservoir. An attractive approach is to integrate the bath degrees of freedom out via a master equation. Here we show how accurate this approach is by comparing it to an exact solution in the case of a tight-binding dissipative-driven model of fermions coupled to an external fermionic bath, and how to actually simulate it on a currently available IBM quantum computer. We also address the case of an interacting dissipative-driven finite size system, i.e. a three-site Hubbard model with on-site interaction driven by an external field and coupled to a bath. Here, we obtain many of the qualitative features already displayed in the thermodynamic limit. The biggest challenge in implementing these ideas on current quantum computers lies with the need for partial resetting of qubits. We discuss strategies to implement on commercially available hardware and what might be possible with academic machines (such as those available at Mainz).
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Sondertermin und -ort |
16 Jan 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 11:30 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122 |
| Dr. Dongwook Go, Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich | |
Electrical control of magnetism is a central theme in the field of spin-orbitronics. Current scheme relies on electrical generation of the spin current/density by utilizing the spin-orbit coupling (SOC) instead of using an extra ferromagnet (FM) as a spin polarizer. For example, in a bilayer structure consisting of a FM layer and a nonmagnet (NM) layer, spin current and density can be induced by the spin Hall effect in the NM and Rashba-Edelstein effect at the NM/FM interface, respectively. However, there has been a missing piece in spin-orbitronics so far: electrons carry angular momentum in the orbital wave function as well as in the spin. In this seminar, I demonstrate that the orbital degree of freedom exhibits rich dynamical phenomena, which is in contrast to a common expectation that the orbital is quenched in solids.
In the first part, I explain how to electrically generate the orbital angular momentum. Here, I introduce concepts of the orbital Rashba-Edelstein effect [1] and the orbital Hall effect [2], which are orbital analogs of the Rashba effect and the spin Hall effect, respectively. These are not only parental effects for their spin analogs, such that the spin phenomena follow the orbital phenomena by the SOC, but also present even in the absence of the SOC. In the second part, I focus on the consequence of the injection of the orbital angular momentum into the FM. As the spin injection gives rise to the spin torque (ST), the orbital injection results in torque on the magnetic moment, which we call orbital torque (OT) [3]. In the mechanism of the OT, it is not necessary to prepare the spin current or density beforehand as in the conventional mechanisms such as the spin Hall effect and Rashba-Edelstein effect. Since both OT and ST contribute to magnetic dynamics, it opens a route to enhancing the torque efficiency in spin-orbitronic devices. Interestingly, we notice that the sign of the torque efficiency in the NM/FM bilayer can be opposite to the sign of the spin Hall effect in the NM if the sign of the OT differs from that of the ST. As a prototypical example, I compare Fe/W(110) and Ni/W(110) bilayers from first principles calculation and discuss qualitatively distinct features of the OT for the experimental detection [4]. As the study on the orbital dynamics has started very recently, I briefly discuss future directions for consistent understanding of entangled dynamics of the spin and orbital degrees of freedom in solids.
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Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7 |
| Shane P. Kelly, Theoretical Division, LANL, Los Alamos, USA | |
In recent years, many experimental platforms have succeeded in producing quantumsystems that, on relevant time scales, are completely isolated from an environment.
This opens the possibility of observing equilibrium states that are not described by standard thermal ensembles and long time dynamics that indefinitely maintain memory of initial states.
In this talk, I discuss two mechanisms for this to occur: many body localization (MBL) and a novel mechanism which occurs in the semi-classical limit of a large spin.
In the first part of my talk, I will discuss the phenomenon of MBL in a disordered spin chain and its effects when coupled to a small environment.
We model this small environment as a clean spin chain and find that, under sufficient coupling and disorder, the dirty chain can induce an MBL effect in the clean chain.
In the second part of my talk, I will discuss the dynamics of a large spin evolving with a non-linear hamiltonian.
Using semi-classical techniques, we identify when the spin does and does not thermalize.
In doing so, we find a novel mechanism for the breakdown of thermalization based on the slow dynamics of an unstable fixed point.
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20 Jan 2020
Institutsseminar Kern- und Hadronenphysik
Institut für Kernphysik 14:00 Uhr s.t., HS Kernphysik, Becherweg 45 |
| Christoph Matejcek, Mainz | |
Low-energy beam transport system for MESA | |
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Seminar für Kern- und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie |
| Dr. Zsolt Baranyi, Universität BRACCO | |
Thema folgt | |
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Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 16:15 Uhr s.t., QUANTUM Seminarraum (02-427), Institut für Physik, Staudingerweg 7 |
| Dr. Guanghua Du, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China | |
When heavy ion beam with energy from MeV to GeV is incident on the target material, the target material distributed along the ion trajectory will be excited or ionized, which will cause lattice damage, polymer chain break or cross-linking in the material and then result in nanoscale latent track, cluster damage and single event effect. The high energy microbeam facility of Lanzhou National Laboratory of Heavy Ion Accelerator is the highest energy microbeam system in the world which uses triplet-quadrupole magnets to produce micron sized high energy ion beams of up to several GeVs. This talk first introduces the accelerator complex and nuclear physics activity at Lanzhou National Lab, and then focuses on the interdisciplinary application of the high energy microbeam facility, including single event effect studies, single ion hitting, nanomaterials, and biomedical studies. | |
Sondertermin und -ort |
21 Jan 2020
Physikalisches Kolloquium
Institut für Kernphysik, Johann Joachim Becher Weg 45 16:00 Uhr s.t., HS KPH |
| Professor Victorino Franco, Condensed Matter Physics, Universidad de Sevilla | |
Phase Transitions and Critical Phenomena | |
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Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik 12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |
| Olga Lozhkina, Inst. f. Physik | |
tba | |
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Theory of Condensed Matter: Hard Condensed Matter
Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9) |
| Souvik Paul, Christian-Albrechts-Universität zu Kiel | |
Magnetic skyrmions, localized spin structure with topological protection, have become a research hotspot as they show promise for future memory and logic devices. The key challenges for applications are to achieve small bits and stability of those skyrmionic bits. Research shows that transition-metal interfaces (TMI) and multilayers are a very promising class of systems to realize nanometer-sized and stable magnetic skyrmions. Therefore, a lot of effort has been put to tailor the properties of these systems for application.
In this direction, using first-principles methods, we have proposed ultrathin films, Fe/Rh and Rh/Fe bilayers on Re(0001) substrate, which show various spin structures at the interface including isolated skyrmions, depending on the stacking order of Fe/Rh and Rh/Fe bilayers. This study would encourage the experimentalist to check our predictions and would generate more investigations on other bilayers on Re(0001).
The other topic I would focus on is the effect of higher-order exchange interactions (HOI) on the stability of skyrmions. HOI are shown to stabilize magnetic ground states in transition-metal ultrathin films, however, their role on the stability of metastable skyrmions has note been investigated yet. We showed that the HOI increase the stability of skyrmions by a large amount at TMI. This study opens up a route to tune skyrmions stability and lifetime in ultrathin films.
[1] Nat. Nanotechnol. 8, 899–911 (2013)
[2] Sci. Rep. 4, 6784 (2014)
[3] Nat. Commun. 5, 4652 (2014)
[4] arXiv:1912.03465
[5] Nat. Phys. 7, 713 (2011)
[6] Phys. Rev. Lett. 120, 207201 (2018)
[7] Phys. Rev. Lett. 120, 207202 (2018)
[8] arXiv:1912.03474 | |
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22 Jan 2020
PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |
| Assumpta Parreno, Universitad de Barcelona | |
A central goal of Nuclear Physics is to obtain a first-principles description of the properties and interactions of nuclei from the underlying theory of the strong interaction, Quantum Chromodynamics (QCD). Being the theory that governs the interactions between the basic building blocks of matter, quarks and gluons, it is also responsible for confining those primary pieces into hadronic states, binding neutrons and protons through the nuclear force to give the different elements in the periodic table. Nevertheless, due to the large complexity of the quark-gluon dynamics, one cannot obtain analytical solutions of QCD in the energy regime relevant to nuclear physics. In order to address this problem, numerical solutions of QCD can be obtained in a finite volume through its formulation in a Euclidean discretized space-time. I will present the results of our study in the two-baryon sector for different values of the light quark masses, as well as for the very light A=3,4 nuclei.
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23 Jan 2020
Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7 |
| Dr. Maria Chekhova, Institut für Optik, Information und Photonik, Universität Erlangen | |
Spontaneous parametric down-conversion is the workhorse of quantum optics. This process is used to generate entangled photon pairs and heralded single photons. When strongly pumped, spontaneous parametric down-conversion generates so many photon pairs that they overlap and form radiation with almost laser brightness. Despite being bright, this radiation manifests nonclassical effects: quadrature squeezing, photon-number correlations, and macroscopic entanglement. It has no coherent component and can be considered as amplified vacuum noise; it is therefore often called bright squeezed vacuum. In addition, strong photon-number fluctuations of bright squeezed vacuum make it extremely efficient for pumping multiphoton effects.
My talk will cover this and other applications of strongly pumped parametric down-conversion. In addition, I will talk about the other extreme case of this process. Namely, if photon pairs are generated in a very thin nonlinear layer, the process does not require phase matching – in other words, the momentum of the pump photon is not conserved by the daughter photons. To demonstrate this, I will show the results of generating photon pairs from a 300 nm layer. This nanoscale generation of entangled photons offers unique radiative characteristics: the frequency-angular spectrum is extremely broad and as such it promises subwavelength and subcycle two-photon correlation widths in position and time, respectively. Additionally, it gives an insight into the subwavelength resonances for vacuum fluctuations.
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SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122 |
| Stéphane Mangin, Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, France | |
During the last decade all-optical ultrafast magnetization switching in magnetic material thin film without the assistance of an applied external magnetic field has been explored [1,2]. It has been shown that femto-second light pulses can induce magnetization reversal in a large variety of magnetic materials [3,4]. However, so far, only certain particular ferrimagnetic thin films exhibit magnetization switching via a single femto-second optical pulse. We will present the single-pulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spin-valve structure and further show that the four possible magnetic configurations of the spin valve can be accessed using a sequence of single femto-second light pulses. Our experimental study reveals that the magnetization states are determined by spin-polarized currents generated by the light pulse interactions with the GdFeCo layer [5]. A detail study showing how spin-polarized currents are generated and how they interact with magnetic layers (Ferromagnetic or Ferrimagnetic) to lead to magnetization switching will be presented. | |
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24 Jan 2020
Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik 13:30 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431 |
| Mona Minakshee Manjaree Bhukta , National Institute of science education and research, Bhubaneswar, India | |
1.Thermal diffusion of nπ Skyrmion and Skyrmion bags Skyrmionics have recently emerged as active field of research because of their potential applications in high density data storage technology and logic gate computing. Magnetic skyrmions correspond to localized whirling spin configurations, which are characterized by a topological charger (Q). Recent atomistic simulations and experimental finding ensure the diffusive behaviour of skyrmion at finite temperatures in ultrathin model, which open up the possibility of application thermal induced skyrmion dynamics in probabilistic computing. In this work we studied the thermal diffusion of nπ skyrmion up to n= 5 and N skyrmion bag (N (= 1-6) skyrmion surrounded by a bigger skyrmion with opposite chirality) using atomistic spin simulation on Pt_{0.95}/Ir_{0.05} on Pd (111) bilayer by statistically averaging out 100s of these spin texture. Further the SkHE of all these structures has been calculated using both simulation and analytics.
2.Frustrated Skyrmionic States in synthetic Antiferromagnet The spherical topology of a skyrmion leads to an extra force, that acts on moving skyrmion, pointing perpendicular to its velocity. This deviates the path of the skyrmion towards the edge of the nanotrack and this phenomenon is referred as the Skyrmion Hall effect (SkHE). In an antiferromagnetically exchange-coupled bi-layer nanotrack, this SkHE could be suppressed without affecting the topological protection of the skyrmion. Recently it is shown that skyrmion in frustrated ferromagnets have more helicity and vorticity degrees of freedom in compared with the skyrmion stabilized by Dzyaloshinskii-Moriya Interaction (DMI). In this work, we attempted to model a system using micromagnetic simulation to induce frustration by taking RKKY interaction as perturbation in a Synthetic antiferromagnet (SAF). The frustration in the system could be due to the equivocation of DMI between two antiferromagnetically coupled layer. We not only found the existence of Q = 0 skyrmion, but also able to stabilize the skyrmion and antiskyrmion in the same layer. Later we deposited Ta/(Pt/Co)_2/Ir(x)/Co/Pt (x= 0.5 and 1.0 nm) on Silicon substrate using DC magnetron sputtering to optimize the SAF nature of the thin films and to observe the domain images using Kerr Microscope. | |
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27 Jan 2020
Institutsseminar Kern- und Hadronenphysik
Institut für Kernphysik 14:00 Uhr s.t., HS Kernphysik, Becherweg 45 |
| Alexey Tyukin, Mainz | |
Momentum transfer reconstruction for the P2 Experiment | |
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Seminar für Kern- und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie |
| Dr. Christian Smorra, Institut für Physik, JGU Mainz | |
Precision measurements with antiprotons and transportable traps | |
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Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |
| Michael Wurm, Institut für Physik | |
THEIA: Chertons, scintons and other new discoveries in low-energy neutrino physics | |
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28 Jan 2020
Physikalisches Kolloquium
Institut für Kernphysik, Johann Joachim Becher Weg 45 16:00 Uhr s.t., HS KPH |
| Professor Manfred Popp, Karlsruher Institut für Technologie | |
Was Hitlers Atombombe verhinderte - Kernphysik während des 2. Weltkrieges | |
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Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik 12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |
| Stanislav Bodnar, Inst. f. Physik | |
Manipulation of Néel vector in antiferromagnetic Mn2Au by current and magnetic field pulses | |
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Theorie-Palaver
Institut für Physik 14:30 Uhr s.t., MITP Seminar Room |
| Fabian Lange, RWTH Aachen | |
The Gradient-Flow formalism was primarily introduced for simulations of Quantum Chromodynamics (QCD) on the lattice and has now found widespread use in this field. In addition, it offers the potential for cross-fertilization between perturbative and lattice calculations.
In my talk I will introduce the Gradient-Flow formalism and outline the perturbative approach. Afterwards, I will present two examples of its applications. First, I will show how it could be used to extract the strong coupling constant from lattice simulations. As second application, I will illustrate how it helps to define the energy-momentum tensor of QCD on the lattice. | |
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29 Jan 2020
PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |
| Jonathan Butterworth, UCL London | |
Particle-level, differential measurements made in fiducial regions of phase-space at colliders have a high degree of model-independence and can therefore be compared in a very generic way not only to precision Standard Model predictions, but to beyond the Standar Model physics implemented in Monte Carlo generators. This allows a wider array of final states to be considered than is typically the case, as well as a wider array of specific models, and optimises the long-term impact of precision LHC data. I present a method of exploiting this, with examples.
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30 Jan 2020
Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7 |
| Prof. Dr. Philipp Haslinger, Atominstitut, TU Wien, Österreich | |
Atom interferometry has proven within the last decades its surprising versatility to sense with high precision tiniest forces. In this talk I will give an overview of our recent work using an optical cavity enhanced atom interferometer to sense with gravitational strength for fifths forces [1,2] and for an on the first-place counterintuitive inertial property of blackbody radiation [3].
Blackbody (thermal) radiation is emitted by objects at finite temperature with an outward energy-momentum flow, which exerts an outward radiation pressure. At room temperature e. g. a cesium atom scatters on average less than one of these blackbody radiation photons every 10^8 years. Thus, it is generally assumed that any scattering force exerted on atoms by such radiation is negligible. However, particles also interact coherently with the thermal electromagnetic field [4] and this leads to a surprisingly strong force acting in the opposite direction of the radiation pressure [3].
If dark energy, which drives the accelerated expansion of the universe, consists of a light scalar field it might be detectable as a “fifth force” between normal-matter objects. In order to be consistent with cosmological observations and laboratory experiments, some leading theories use a screening mechanism to suppress this interaction. However, atom-interferometry presents a tool to reduce this screening [5] on so-called chameleon models [6]. By sensing the gravitational acceleration of a 0.19 kg in vacuum source mass which is 10^-8 times weaker than Earth´s gravity, we reach a natural bound for cosmological motivated scalar field theories and were able to place tight constraints [1,2].
[1] P. Hamilton, M. Jaffe, P. Haslinger, Q. Simmons, H. Müller, J. Khoury, Atom-interferometry constraints on dark energy, Science. 349 (2015) 849–851.
[2] M. Jaffe, P. Haslinger, V. Xu, P. Hamilton, A. Upadhye, B. Elder, J. Khoury, H. Müller, Testing sub-gravitational forces on atoms from a miniature, in-vacuum source mass, Nat. Phys. 13 (2017) 938–942.
[3] P. Haslinger, M. Jaffe, V. Xu, O. Schwartz, M. Sonnleitner, M. Ritsch-Marte, H. Ritsch, H. Müller, Attractive force on atoms due to blackbody radiation, Nat. Phys. 14 (2018) 257–260.
[4] M. Sonnleitner, M. Ritsch-Marte, H. Ritsch, Attractive Optical Forces from Blackbody Radiation, Phys. Rev. Lett. 111 (2013) 23601.
[5] C. Burrage, E.J. Copeland, E.A. Hinds, Probing dark energy with atom interferometry, J. Cosmol. Astropart. Phys. 2015 (2015) 042–042. doi:10.1088/1475-7516/2015/03/042.
[6] B. Elder, J. Khoury, P. Haslinger, M. Jaffe, H. Müller, P. Hamilton, Chameleon dark energy and atom interferometry, Phys. Rev. D. 94 (2016) 44051.
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SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122 |
| Prof. Matthias Wuttig, RWTH Aachen University of Technology, Germany | |
It has been a long-time dream of mankind to design materials with tailored properties. In recent years, the focus of our work has been the design of phase change materials for applications in data storage. In this application, a remarkable property portfolio of phase change materials (PCMs) is employed, which includes the ability to rapidly switch between the amorphous and crystalline state. Surprisingly, in PCMs both states differ significantly in their properties. This material combination makes them very attractive for data storage applications in rewriteable optical data storage, where the pronounced difference of optical properties between the amorphous and crystalline state is employed. This unconventional class of materials is also the basis of a storage concept to replace flash memory. This talk will discuss the unique material properties, which characterize phase change materials. In particular, it will be shown that only a well-defined group of materials utilizes a unique bonding mechanism (‘Bond No. 6’), which can explain many of the characteristic features of crystalline phase change materials. Different pieces of evidence for the existence of this novel bonding mechanism, which we have coined metavalent bonding, will be presented. In particular, we will present a novel map, which separates the known strong bonding mechanisms of metallic, ionic and covalent bonding, which provides further evidence that metavalent bonding is a novel and fundamental bonding mechanism. This insight is subsequently employed to design phase change materials as well as thermoelectric materials. Yet, the discoveries presented here also force us to revisit the concept of chemical bonds and bring back a history of vivid scientific disputes about ‘the nature of the chemical bond’. | |
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31 Jan 2020
Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau Sonderseminar: 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |
| Philipp Arras, MPI Astrophysics, Garching | |
Information field theory and applications in calibration and imaging algorithms | |
Sonderseminar | |
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03 Feb 2020
Seminar für Kern- und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie |
| Prof. Dr. Bernd Krause, Universität Rostock | |
Thema folgt | |
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Institutsseminar Kern- und Hadronenphysik
Institut für Kernphysik 14:00 Uhr s.t., HS Kernphysik, Becherweg 45 |
| Oliver Noll, Mainz | |
Digital signal processing for the PANDA electromagnetic calorimeter | |
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Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |
| Christopher Hils, Insitut für Physik | |
Ultra-low energy calibration of the XENON1T detector with an internal 37Ar source | |
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04 Feb 2020
Physikalisches Kolloquium
Institut für Kernphysik, Johann Joachim Becher Weg 45 16:00 Uhr s.t., HS KPH |
| Dr. Friederike Otto, ECI, University of Oxford | |
COLLOQUIUM CANCELLED! Angry Weather How Climate Change is affecting extreme Weather around the World | |
COLLOQUIUM CANCELLED! |
Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik 12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |
| Amrit R. Pokharel, Inst. f. Physik | |
Carrier relaxation dynamics in Kondo insulator YbB12 | |
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Theorie-Palaver
Institut für Physik 14:30 Uhr s.t., MITP seminar room |
| Avirup Ghosh, Harish Chandra Research Institute | |
The existence of Dark Matter (DM) as one of the major component of our universe is inevitable today. Though there are several evidences of DM, all of them are gravitational in nature. The particle nature of DM is yet unknown. The most popular theory of particle DM is Weakly Interacting Massive Particles(WIMP) which though very interesting from the point of view of naturalness, is not yet tested in experiments. On the other hand, Feebly Interacting Massive Particles (FIMP) as an alternative scenario is gaining attention in recent times which due to their feeble interaction can not be observed in current generation of experiments. I shall discuss in my talk how in some FIMP scenarios the tiny coupling of FIMP DM give rise to interesting signals. | |
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06 Feb 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122 |
| Markus Garst, KIT Karlsruhe, Germany | |
The weak Dzyaloshinskii-Moriya interaction (DMI) in chiral magnets stabilizes spatially modulated magnetic textures like helices and skyrmion crystals. In this talk we focus on the dynamical properties of such textures. In the field-polarized phase of chiral magnets, the DMI results in a pronounced non-reciprocity of the magnon spectrum, i.e. the excitation energy is not symmetric with respect to an inversion of the wavevector. In the conical helix phase, the spin waves experience Bragg scattering off the periodic magnetic texture that leads to a backfolding of the magnon spectrum. As a result, the spectrum becomes reciprocal for wavevectors along the helix axes. However, the distribution of spectral weight in the spin structure factor remains non-reciprocal as confirmed by inelastic neutron scattering [1,2]. For wavevector with a finite perpendicular component of the wavevector, dipolar interactions induce a non-reciprocity which was detected by Brillouin light scattering [3]. We also discuss the spin wave spectrum of the skyrmion crystal phase where the non-trivial topology leads to an emergent electrodynamics for magnons. As a result the spectral weight of the spin structure factor is widely distributed at high energies. The spin wave excitations propagating along the skyrmion strings also exhibit a non-reciprocity as confirmed by spin wave spectroscopy [4]. Finally, we discuss the non-linear dynamics of a single skyrmion string [5]. | |
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Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 15:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122 |
| Kelvin van Hoorn, Technical University of Eindhoven, The Netherlands | |
Magnetic field sensors based on deflection of membranes | |
Sonderseminar | |
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07 Feb 2020
Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 15:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Stock, Raum 03-431 |
| Chi Fang, University of Chinese Academy of Sciences, Beijing, China | |
The application potential of spin-orbit-torques in magnetic random access memory attracts great attention and research interest in spin-orbit coupling in heavy metals like Platinum and Tantalum. Thus the spin relaxation time τ_s, as a crucial parameter to investigate spin relaxation mechanism in the heavy metals, requires accurate and effective estimation. A traditional three-terminal method is also widely utilized to estimating τ_s of semiconductors and light metals. Its reliability, however, has recently been challenged by some experiments in which tunneling anisotropic magnetoresistance (MR) or spin blockage MR rather than the MR induced by spin injection and subsequent Hanle effect is more appropriate to explain the data.
In this talk, I will introduce the spin-injection-induced magnetoresistance of which the magnitude is comparable with other MR phenomena originating from the tunnel barrier is observable at room temperature as well as low temperatures in the second harmonic signals. Three-terminal and second harmonic method are combined in our measurement in Pt and Ta systems. Furthermore, we could estimate τ_s of heavy metals through fitting the signal with Lorentz function. This experimental approach make it possible to directly acquire τ_s of heavy metals with electrical method. | |
Sonderseminar | |
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19 Feb 2020
Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 14:30 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Stock, Raum 03-431 |
| Dr. Kunie Ishioka, National Institute for Materials Science, Tsukuba, Japan | |
Mittwoch, den 19. Februar 2020 um 14:30
im MEDIEN-Raum, Staudinger Weg 7, 03-431
Ultrafast Carrier and Phonon Dynamics of Hybrid Lead Halide Perovskite
Kunie Ishioka
National Institute for Materials Science, Tsukuba, Japan
Inorganic-organic hybrid lead halide perovskites, consisting of the soft lead halide octahedral framework and the organic molecular cations, are among the key materials for the next generation photovoltaics. In the first half of my talk I present on the charge separation dynamics at the interfaces of methylammonium lead iodide MAPbI3 with three different hole transport materials (HTMs) [1]. Here, the differential transmission signals revealed the hole injection from the perovskite to organic HTMs to occur on the time scale of 1 ps, whereas that to inorganic NiOx on an order of magnitude longer timescale. The anti-correlation with the fill factor of the solar cells suggests that the interfacial quality was responsible. In the second half I present our recent results on the coherent phonons of MAPbI3 [2]. We observe periodic modulations in the transient transmissivity due to the photoinduced libration and torsion of the methylammonium cations and the deformation of the PbI6 octahedral framework. The frequencies of the cation torsion and the octahedral deformations exhibited downchirps, in agreement with theoretically predicted strong anharmonicities of their vibrational potentials. | |
Sonderseminar | |
Sondertermin |
27 Feb 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122 |
| Shefali Vaidya, IRCELYON, Lyon, France | |
Molecular magnets to phase changing coordination polymers: criteria an challenges for molecules for their potential application in memory storage | |
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05 Mar 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122 |
| Thomas Allison, Stony Brook University, NY, USA | |
Time-resolved ARPES at 88 MHz repetition rate with full 2π collection | |
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Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |
| Fabian Kössel, Institut für Physik | |
Emerging patterns from the collective dynamics of microswimmers in an external field | |
Trial PhD defense talk |
10 Mar 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., Galilei seminar room (Staudinger Weg 9, room 01-128) |
| Mehrdad Elyasi, Tohoku University, Sendai, Japan | |
Magnons for Quantum Information | |
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12 Mar 2020
SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie
SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ seminar room (Staudinger Weg 9, 3rd floor, room 03-122) |
| Dr. Aga Shahee, Seoul University | |
Doping tunable multiferroicity in PbCu3TeO7 and magneto-electric coupling in Van der Waal CuCrP2S6 | |
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Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |
| Jan Rothörl, Institut fuer Physik | |
Creating 3D structures of diploid cells from Hi-C data using a Molecular Dynamics approach | |
Master Colloquium |
13 Mar 2020
Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 11:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 431 |
| Jonas Knobel, Universität Würzburg | |
New directions in spintronics heading towards devices based on antiferromagnetic materials require a fundamental understanding of the underlying physics. CuMnSb grown by molecular beam epitaxy (MBE) on GaSb substrates can provide a model system of a thin film antiferromagnet. I will report on the growth of virtually unstrained pseudomorphic single crystals showing clear antiferromagnetic behavior. The ordering temperature of CuMnSb between 50K and 62K lies well within the reach of standard cryostats. This allows to diff erentiate thermal from magnetic properties in transport devices.
I will first discuss the epitaxial growth of a GaSb buff er layer needed for a sharp interface. Subsequent CuMnSb growth is highly dependent on the flux ratios of the respective elements. I will explain their influence on crystal properties and how reflection high-energy electron di ffraction (RHEED) is used to control the growth process. | |
Sonderseminar | |
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Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell
Institut für Physik Sonderseminar: 14:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 431 |
| Kanji Furuta, Department of Materials Science and Engineering, Nagoya University, Japan. | |
MAX phase compounds have recently attracted much attention due to their possible application to the production of a new class of two-dimensional systems called MXenes [1]. Mo4Ce4Al7C3 is affiliated with the MAX phase and in a family of RE-based nanolaminates with a chemical formula of Mo4RE4Al7C3. From magnetization measurements, x-ray absorption near-edge structure (XANES), and x-ray magnetic circular dichroism (XMCD), a ferromagnetism below a Curie temperature of TC ~ 10.5 K and a mixed-valence states of the Ce 4f electrons have been reported [2].
To understand the origin of electronic/magnetic properties of Mo4Ce4Al7C3, we have performed angle-resolved photoemission spectroscopy (ARPES) on Mo4Ce4Al7C3 single-crystals. As a result, we have succeeded to obtain the electronic band structure as well as Fermi surface of this system. From the comparison between Ce 4d-4f on and off resonant ARPES, strong Ce 4f character at the electron pocket around the G point has been elucidated. Furthermore, we have found a clear increase of the Ce 4f spectral weight below TC. The results suggest that itinerant Ce 4f electrons may play an important role in the magnetic properties of Mo4Ce4Al7C3.
REFERENCES
[1] M. Barsoum, MAX phases (Wiley, Weinheim, 2013).
[2] Q. Tao et al., Phys. Rev. Mat. 2, 114401 (2018). | |
Sonderseminar | |
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zukünftige Termine
02 Apr 2020
Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |
| Bing Li, Postdoctoral researcher, Institute of physics, JGU Mainz | |
Shaping membrane vesicles by adsorption of a semiflexible polymer | |
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16 Apr 2020
Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |
| Ashreya Jayaram, Institut für Physik, JGU, PhD student | |
Collective Behaviour of Anisotropic Active Particles | |
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