Jahresübersicht für das Jahr 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  

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 MonojetEreignissen bei 13TeV mithilfe des ATLASDetektors am LHC  
Bachelorkolloqium 
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 MicroCalorimeters a New Key Technology  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Cristina Lazzeroni, University Birmingham, UK  
The decay K+→π+vv ̅, with a very precisely predicted branching ratio of less than 1010, 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 decayinflight technique. NA62 took data so far in 20162018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv ̅, entering the domain of 1010 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.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., LorentzRaum (05127), 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 nonequilibrium phase diagrams. The first part of the talk will discuss longrange 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 prethermalisation are required to stabilise a strongly interacting nonequilibrium steady state. Time permitting, I will advertise some novel results on a purely dissipative analogue of longrange interacting quantum simulators, which can be implemented in quantum optics or solid state platforms.  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie 
Dr. Marine Vandebrouck, CEA Saclay  
243Es, 249Md: from production crosssections measurement to spectroscopy  Perspectives at GANILSPIRAL2/S3  

Theoriekolloquium
Die Dozierenden der Theoretischen Physik Sonderseminar: 14:00 Uhr s.t., Medienraum, Staudinger Weg 7, 03431 
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 highenergy 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 operatorbased 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, 03431 
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  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 10:00 Uhr s.t., MEDIENRaum, Staudingerweg 7, 3. Stock, Raum 03431 
Abhishek Erram , Indian Institute of Technology Kharagpur  
In this work, we have made a polycrystalline sample of Dy2BaNiO5 by a standard solidstate reaction route. The formation of the compound was ascertained by xray 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 zerofieldcooled (zfc) and fieldcooled (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 Xray diffraction (XRD). Magnetic behavior was also studied. Results show that of formation of thin film. Signs of magnetic behavior was also evident.  
Sonderseminar  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, 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 DysonSchwinger and BetheSalpeter 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 fourquark systems I will summarize results for light quarks and discuss recent progress on discriminating between tetraquark, molecule or hadroquarkonium configurations in heavylight systems.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 10:30 Uhr s.t., QUANTUM Seminarraum (02427), 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 drivendissipative 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 tightbinding dissipativedriven 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 dissipativedriven finite size system, i.e. a threesite Hubbard model with onsite 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).
 
Sondertermin und ort 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 11:30 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
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 spinorbitronics. Current scheme relies on electrical generation of the spin current/density by utilizing the spinorbit 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 RashbaEdelstein effect at the NM/FM interface, respectively. However, there has been a missing piece in spinorbitronics 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 RashbaEdelstein 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 RashbaEdelstein effect. Since both OT and ST contribute to magnetic dynamics, it opens a route to enhancing the torque efficiency in spinorbitronic 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.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., LorentzRaum (05127), 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 semiclassical 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 nonlinear hamiltonian.
Using semiclassical 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.
 

Institutsseminar Kern und Hadronenphysik
Institut für Kernphysik 14:00 Uhr s.t., HS Kernphysik, Becherweg 45 
Christoph Matejcek, Mainz  
Lowenergy beam transport system for MESA  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie 
Dr. Zsolt Baranyi, Universität BRACCO  
Thema folgt  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 16:15 Uhr s.t., QUANTUM Seminarraum (02427), 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 crosslinking 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 tripletquadrupole 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 
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  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 12:00 Uhr s.t., NewtonRaum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) 
Olga Lozhkina, Inst. f. Physik  
tba  

Theory of Condensed Matter: Hard Condensed Matter
Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01128 (Staudinger Weg 9) 
Souvik Paul, ChristianAlbrechtsUniversität 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 transitionmetal interfaces (TMI) and multilayers are a very promising class of systems to realize nanometersized 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 firstprinciples 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 higherorder exchange interactions (HOI) on the stability of skyrmions. HOI are shown to stabilize magnetic ground states in transitionmetal 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  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Assumpta Parreno, Universitad de Barcelona  
A central goal of Nuclear Physics is to obtain a firstprinciples 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 quarkgluon 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 spacetime. I will present the results of our study in the twobaryon sector for different values of the light quark masses, as well as for the very light A=3,4 nuclei.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., LorentzRaum (05127), Staudingerweg 7 
Dr. Maria Chekhova, Institut für Optik, Information und Photonik, Universität Erlangen  
Spontaneous parametric downconversion is the workhorse of quantum optics. This process is used to generate entangled photon pairs and heralded single photons. When strongly pumped, spontaneous parametric downconversion 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, photonnumber 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 photonnumber 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 downconversion. 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 frequencyangular spectrum is extremely broad and as such it promises subwavelength and subcycle twophoton correlation widths in position and time, respectively. Additionally, it gives an insight into the subwavelength resonances for vacuum fluctuations.
 

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
Stéphane Mangin, Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, France  
During the last decade alloptical 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 femtosecond 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 femtosecond optical pulse. We will present the singlepulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spinvalve structure and further show that the four possible magnetic configurations of the spin valve can be accessed using a sequence of single femtosecond light pulses. Our experimental study reveals that the magnetization states are determined by spinpolarized currents generated by the light pulse interactions with the GdFeCo layer [5]. A detail study showing how spinpolarized currents are generated and how they interact with magnetic layers (Ferromagnetic or Ferrimagnetic) to lead to magnetization switching will be presented.  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 13:30 Uhr s.t., MEDIENRaum, Staudingerweg 7, 3. Stock, Raum 03431 
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 (= 16) 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 exchangecoupled bilayer 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 DzyaloshinskiiMoriya 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.  

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  

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  

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 lowenergy neutrino physics  

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  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 12:00 Uhr s.t., NewtonRaum, 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  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., MITP Seminar Room 
Fabian Lange, RWTH Aachen  
The GradientFlow 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 crossfertilization between perturbative and lattice calculations.
In my talk I will introduce the GradientFlow 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 energymomentum tensor of QCD on the lattice.  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Jonathan Butterworth, UCL London  
Particlelevel, differential measurements made in fiducial regions of phasespace at colliders have a high degree of modelindependence 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 longterm impact of precision LHC data. I present a method of exploiting this, with examples.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14:00 Uhr s.t., LorentzRaum (05127), 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 firstplace counterintuitive inertial property of blackbody radiation [3].
Blackbody (thermal) radiation is emitted by objects at finite temperature with an outward energymomentum 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 normalmatter objects. In order to be consistent with cosmological observations and laboratory experiments, some leading theories use a screening mechanism to suppress this interaction. However, atominterferometry presents a tool to reduce this screening [5] on socalled 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, Atominterferometry 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 subgravitational forces on atoms from a miniature, invacuum source mass, Nat. Phys. 13 (2017) 938–942.
[3] P. Haslinger, M. Jaffe, V. Xu, O. Schwartz, M. Sonnleitner, M. RitschMarte, H. Ritsch, H. Müller, Attractive force on atoms due to blackbody radiation, Nat. Phys. 14 (2018) 257–260.
[4] M. Sonnleitner, M. RitschMarte, 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:10.1088/14757516/2015/03/042.
[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.
 

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
Prof. Matthias Wuttig, RWTH Aachen University of Technology, Germany  
It has been a longtime 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 welldefined 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’.  

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, 01122, Staudingerweg 9 
Philipp Arras, MPI Astrophysics, Garching  
Information field theory and applications in calibration and imaging algorithms  
Sonderseminar  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16:00 Uhr s.t., Seminarraum Kernchemie 
Prof. Dr. Bernd Krause, Universität Rostock  
Thema folgt  

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  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum 
Christopher Hils, Insitut für Physik  
Ultralow energy calibration of the XENON1T detector with an internal 37Ar source  

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., NewtonRaum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) 
Amrit R. Pokharel, Inst. f. Physik  
Carrier relaxation dynamics in Kondo insulator YbB12  

TheoriePalaver
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.  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Markus Garst, KIT Karlsruhe, Germany  
The weak DzyaloshinskiiMoriya 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 fieldpolarized phase of chiral magnets, the DMI results in a pronounced nonreciprocity 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 nonreciprocal as confirmed by inelastic neutron scattering [1,2]. For wavevector with a finite perpendicular component of the wavevector, dipolar interactions induce a nonreciprocity which was detected by Brillouin light scattering [3]. We also discuss the spin wave spectrum of the skyrmion crystal phase where the nontrivial 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 nonreciprocity as confirmed by spin wave spectroscopy [4]. Finally, we discuss the nonlinear dynamics of a single skyrmion string [5].  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 15:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Kelvin van Hoorn, Technical University of Eindhoven, The Netherlands  
Magnetic field sensors based on deflection of membranes  
Sonderseminar  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 15:00 Uhr s.t., MEDIENRaum, Staudinger Weg 7, 3. Stock, Raum 03431 
Chi Fang, University of Chinese Academy of Sciences, Beijing, China  
The application potential of spinorbittorques in magnetic random access memory attracts great attention and research interest in spinorbit 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 threeterminal 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 spininjectioninduced 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. Threeterminal 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  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 14:30 Uhr s.t., MEDIENRaum, Staudinger Weg 7, 3. Stock, Raum 03431 
Dr. Kunie Ishioka, National Institute for Materials Science, Tsukuba, Japan  
Mittwoch, den 19. Februar 2020 um 14:30
im MEDIENRaum, Staudinger Weg 7, 03431
Ultrafast Carrier and Phonon Dynamics of Hybrid Lead Halide Perovskite
Kunie Ishioka
National Institute for Materials Science, Tsukuba, Japan
Inorganicorganic 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 anticorrelation 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 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Shefali Vaidya, IRCELYON, Lyon, France  
Molecular magnets to phase changing coordination polymers: criteria an challenges for molecules for their potential application in memory storage  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Thomas Allison, Stony Brook University, NY, USA  
Timeresolved ARPES at 88 MHz repetition rate with full 2π collection  

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, 01122, Staudingerweg 9 
Fabian Kössel, Institut für Physik  
Emerging patterns from the collective dynamics of microswimmers in an external field  
Trial PhD defense talk 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., Galilei seminar room (Staudinger Weg 9, room 01128) 
Mehrdad Elyasi, Tohoku University, Sendai, Japan  
Magnons for Quantum Information  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/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 03122) 
Dr. Aga Shahee, Seoul University  
Doping tunable multiferroicity in PbCu3TeO7 and magnetoelectric coupling in Van der Waal CuCrP2S6  

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, 01122, Staudingerweg 9 
Jan Rothörl, Institut fuer Physik  
Creating 3D structures of diploid cells from HiC data using a Molecular Dynamics approach  
Master Colloquium 
Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 11:00 Uhr s.t., MEDIENRaum, 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 highenergy electron di ffraction (RHEED) is used to control the growth process.  
Sonderseminar  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 14:00 Uhr s.t., MEDIENRaum, 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 twodimensional systems called MXenes [1]. Mo4Ce4Al7C3 is affiliated with the MAX phase and in a family of REbased nanolaminates with a chemical formula of Mo4RE4Al7C3. From magnetization measurements, xray absorption nearedge structure (XANES), and xray magnetic circular dichroism (XMCD), a ferromagnetism below a Curie temperature of TC ~ 10.5 K and a mixedvalence states of the Ce 4f electrons have been reported [2].
To understand the origin of electronic/magnetic properties of Mo4Ce4Al7C3, we have performed angleresolved photoemission spectroscopy (ARPES) on Mo4Ce4Al7C3 singlecrystals. 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 4d4f 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  

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, 01122, Staudingerweg 9 
Bing Li, Postdoctoral researcher, Institute of physics, JGU Mainz  
Shaping membrane vesicles by adsorption of a semiflexible polymer  

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, 01122, Staudingerweg 9 
Ashreya Jayaram, Institut für Physik, JGU, PhD student  
Collective Behaviour of Anisotropic Active Particles  
