Wochenübersicht für die Woche vom

20 Jan 2020 bis 26 Jan 2020 (KW 4)

KW3 - KW4 - KW5 - KW6

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

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 (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

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

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

zukünftige Termine
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.

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.

SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122

Prof Stephane Mangin, Nancy, France
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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.