The team of researchers after performing the experiment at SLAC. Credit: Klaus Sokolowski-Tinten, University of Duisburg-Essen.

New Publication in Science Liquid-liquid phase transition in super-cooled phase-change materials

[14.06.2019] Phase-change materials (PCMs) are used in the latest generation of smartphones enabling higher storage densities and energy efficiency. When an electrical or optical pulse is applied to heat these materials locally, they change from a glassy to a crystalline state, and vice versa. These two different states represent the ‘0’ and ‘1’ of the binary code needed to store information. An international team of researchers led by Klaus Sokolowski-Tinten has now succeeded in observing the processes that occur during switching – something that has never been done before because of the short time-scales involved. They used the ultrashort and extremely brilliant X-ray pulses from an X-ray Free Electron laser to resolve the atomic structure changes of two Sb-based PCMs during the entire switching cycle. They found that two liquid states of the materials are involved in the process – one that has more rigid chemical bonds, and which helps stabilize the glassy “off” state at ambient conditions, and one that is rather metallic and can therefore crystallize very quickly to produce the “on” state. These results provide a microscopic understanding on how PCMs work and why some materials are PCMs and others not. More generally, this work and the applied time-domain approach can also help to understand how liquids of other classes of materials behave when they are rapidly super-cooled to temperatures well below the melting point and why some liquids are more likely to form a glass than others. The study, published on June 14th in Science, was coordinated by the University of Duisburg – Essen and European XFEL and carried out at the Linac Coherent Light Source of SLAC National Accelerator Laboratory (Menlo Park, USA). It was was part of an international collaboration including scientists from Forschungszentrum Jülich, Institut Laue-Langevin, Lawrence Livermore National Laboratory, Lund University, Paul Scherrer Institute, SLAC National Accelerator Laboratory, Stanford University, The Spanish National Research Council (CSIC), University of Aachen, and the University of Potsdam.

Original publication:

“Femtosecond X-ray diffraction reveals a liquid-liquid phase transition in phase-change materials”, Zalden et al.

DOI: 10.1126/science.aaw1773

Diversity Award of the University of Duisburg-Essen Dr. Nora Dörmann receives the Diversity Award from the University of Duisburg-Essen

[13.06.2019] Dr. Nora Dörmann has received the Diversity Award of the University of Duisburg-Essen in the category "Managers". The prize was presented on 6 June as part of the Diversity Day by Prorector Prof. Dr. Barabara Buchenau and the speaker of the SFB 1242 Prof. Dr. Uwe Bovensiepen, who also gave the laudatory speech. Mrs. Dörmann is the managing director of the SFB 1242. The prize was awarded in recognition of her commitment to the promotion of women scientists.

2PPE PEEM Micrograph of the focus point of a Fresnel-type grating coupler. After exciting the coupler with femtosecond laser pulses, surface plasmon polaritons propagate from the coupler to the focus point, where they interfere constructively

New Publication in ACS Photonics Focusing Surface Plasmons with Fresnel-Zones

[26.02.2019] In the 19th century, Augustin Jean Fresnel invented his zone-plate; basically a hologram, which - by diffraction - forms a defined focal point if illuminated with a plane light wave. Frank Meyer zu Heringdorf's  TR-PEEM Team has now applied the concept of Fresnel-focusing to surface-plasmon-polaritons, i.e., to electron-density waves that can propagate at metal surfaces with almost the speed of light in vacuum. Instead of focusing traveling plasmon waves by a Fresnel type zone plate, however, the team structured particular Fresnel-type grating couplers that were illuminated by femtosecond laser pulses, and that very effectively excited plasmon waves forming a focus at a desired location. Using their time-resolved photoemission microscope, the team could characterize this  "Fresnel-optics for surface plasmon waves" in detail, and they could follow the formation of the focus in a super-slow motion movie on the femtosecond time-scale. The results were now published in ACS Photonics.

Dr. Stegmann, Philipp (c) private

Award of the Sparkasse Duisburg Outstanding Dissertation

[20.11.2018] Congratulations! Physicist Dr. Philipp Stegmann has been awarded by the Sparkasse Duisburg for his outstanding dissertation on "Generalized factorial cumulants applied to Coulomb-blockade systems", which has been carried out in the working group of Prof. Dr. Jürgen König. In his dissertation, Stegmann developed new theoretical methods for the statistical analysis of charge carrier dynamics in quantum dots and thereby successfully contributed to research activity pursued within the CRC 1242.

Highly Dynamic Solid State Research Prof. Dr. Dmitry Turchinovich joined the CRC 1242

[30.07.2018] They are highly dynamic: The microscopic interaction processes inside solids take place on ultrafast timescales. What exactly happens to the electrons and ions in selected cases and how they affect the electrical, optical and mechanical material properties is investigated by Prof. Dr. Dmitry Turchinovich (40) using ultrashort pulses in THz spectral regime: Prof.Turchinovich who has been appointed as professor in Experimental Physics at the University of Duisburg-Essen in 2017 recently joined the CRC 1242 with a new research project.

Gruppenfoto am Strand während der Summer School 2017 in St. Peter-Ording
(c) Faculty of Physics/UDE

St. Peter-Ording Successful Summer School

[14.08.2017] „Non-equilibrium dynamics“ on the German North Sea coast: About 45 graduate students and postdocs exchanged with national and international researchers and project instructors from the CRC 1242 on current scientific topics from August 7 to 11, 2017 in St. Peter-Ording. In addition to exciting poster sessions, a special highlight was the lecture "Inside Nature-branded journals" by Dr. Luke Fleet, Senior Editor at Nature Physics.

Portrait vom Preisträger Dr. Tim Frigge
(c) Faculty of Physics/UDE

Dies academicus 2017 Outstanding Dissertation

[29.06.2017] Celebrate the best: At the „Dies academicus“, outstanding scientific performances and the most innovative ideas have been awarded at the University of Duisburg-Essen (UDE). At this year's ceremony on June 28, 2017, the experimental physicist Dr. Tim Frigge from the working group of Prof. Michael Horn-von Hoegen received a prize for his dissertation on "Ultrafast structural non-equilibrium dynamics of the optically excited Si(111)(8x2)->(4x1)-In phase transition". In this, Frigge investigated initial structural dynamics of the photoinduced melting of a charge density wave in atomic chains of Indium on a Silicon(111) surface.

Gruppenfoto der Teilnehmerinnen und Teilnehmer vom Doctroral Retreat im Mai 2017
(c) Faculty of Physics/UDE

Doctoral Retreat Sharing Ideas

[10.05.2017] Open discussions between peers to sharing ideas: About 25 scientists are going to meet at the Doctoral Retreat of the CRC 1242 from May 15 to 17, 2017 at „Akademie Klausenhof“ in Hamminkeln. In an open atmosphere lectures, talk sessions, a poster circle and joint activities provide the opportunity to inform themselves about current research and to strengthen the collaboration.

(c) Dr. Andreas Lücke, University of Paderborn

Report in Nature: Observing Live Phase Transition Watching the Atoms Race

[30.03.2017] By comparison, a blink lasts a lifetime – atoms can rearrange themselves within one 350 quadrillionths of a second. As reported in the latest issue of the prestigious journal Nature, scientists of the Center for Nanointegration (CENIDE) and the CRC 1242 at the University of Duisburg-Essen (UDE), together with their colleagues from the University of Paderborn, have been able to observe the movement of an one-dimensional material in real-time. Their research confirms that the acceleration of the atoms could leave even a Porsche standing.

The complete press release can be found here.

Lichtspirale auf Gold
(c) University of Stuttgart

Science Publication The orbital angular momentum of plasmons caught on video

[17.03.2017] Transmitting huge volumes of data and even moving matter using light: These are two of the visions that physicists working in the field of plasmonics have for the future. In a collaboration with colleagues from Haifa (Israel), Kaiserslautern and Stuttgart, scientists at the Center for Nanointegration (CENIDE) at the University of Duisburg-Essen succeeded in producing nanometer-sized plasmon swirls on a metal surface, filming the cycles at 100 attosecond intervals.

The video can be found here. The complete press release can be found here.

Die elektronenmikroskopische Aufnahme zeigt das unbeschädigte Graphen-Gitter auch nach dem Ionenbeschuss. In der hohen Auflösung ist deutlich die Bienenwaben-Struktur aus je sechs Kohlenstoff-Atomen zu erkennen.
(c) AG Schleberger

UDE: 2D Material withstands extremely high current densities Graphene under Fire

[06.02.2017] The particle penetrated the ultra-thin sample with speeds of up to 450 km/s, yet everything
stayed in one piece: This is what happened to a team of international scientists, among them Professor Dr. Marika Schleberger from the Center for Nanointegration (CENIDE) of the University Duisburg-Essen (UDE). Her sample of freestanding graphene was able to balance out the charge of a high-energy ion within femtoseconds and thus prevent a nanoscale explosion. “Nature Communications” reported on this in its  latest issue.

The complete press release can be found here.

(c) CENIDE

International Symposium Ultrafast Soft X-Ray Spectroscopy and Scattering

[16.01.2017] International symposium on ultrafast soft x-ray spectroscopy and scattering on Friday, 27 January: The Collaborative Research Center 1242 of the Faculty of Physics and the Center for Nanointegration Duisburg-Essen (CENIDE) invite you to attend at the NanoEnergyTechnologyCenter (NETZ) on campus Duisburg. International experts exchange ideas such as how to apply the processes and methods for element-specific analysis in complex nanostructures.

Please find directions and a detailed program here.

(c) CENIDE/AG Bovensiepen

Research into Superconductors Tracking the Flow of Energy by Laser

[20.12.2016] Below their critical temperature they conduct the electrical current without resistance and thus extremely efficiently: Until now it has only been known that high-temperature superconductors work – but not how. Physicists at the University of Duisburg-Essen (UDE) have succeeded in tracking the redistribution of the energy in the material. To do this they used a medium which is itself fast enough to register these processes – light. The "Nature Communications" journal has just published their results.

The complete press release can be found here.

(c) Faculty of Physics/UDE

Kick-Off-Meeting Teaming up for Success!

[25.11.2016] Getting to know each other better, professional exchange and networking: Around 80 scientists met at the kick-off-meeting of the CRC 1242 from 21 to 23 November 2016 in the conference center „Physikzentrum“ in Bad Honnef. Numerous lectures, poster presentations and joint activities such as hiking provided the opportunity to inform themselves about current research and to strengthen the cooperation. External speakers from renowned institutions were also invited.

The complete program can be found here.

Photo: René Göke, (c) Faculty of Physics/UDE

UDE Guided Laboratory Tours on 4.11. and 2.12.: Discover High-Performance Lasers

[18.10.2016] Exclusive insights into the laser laboratory of the new CRC 1242 are being offered by the University of Duisburg-Essen (UDE) Faculty of Physics on November 4, 2016 and December, 2, 2016 (17:00, meet at the entrance to the MG building on Duisburg campus). Entrance is free, but registration in advance is necessary as the number of participants is limited.

The complete press release can be found here.

(c) CENIDE

Open Day „WissensNacht Ruhr 2016“ Look behind the Scenes

[04.10.2016] Exciting labs, amazing lectures and exhibits: during the Wissensnacht Ruhr at the Faculty of Physics and the NanoEnergyTechnologyCenter (NETZ) on September 30, 2016, hundreds of visitors went on a discovery tour through the research activities at the Campus Duisburg. They also got an insight into the CRC 1242 about „Non-Equilibrium Dynamics of Condensed Matter in the Time Domain“.

Selected impressions can be found here.

Amran Al-Ashouri (c) private

Award of the Sparkasse Duisburg Outstanding Study Performance

[28.09.2016] Congratulations! Physicist Amran Al-Ashouri from the working group of Prof. Dr. Axel Lorke receives one of this year's study awards of the Sparkasse Duisburg for his outstanding study performance. Al-Ashouri is financially supported as a Lab Student within the CRC1242. For years, the Sparkasse Duisburg has been promoting and supporting the scientific work and research of the University of Duisburg-Essen in a variety of ways. As in the previous years, prizes are awarded for dissertations that meet particularly stringent scientific requirements. At the same time, five outstanding study achievements are awarded.

Photo: René Göke, (c) Faculty of Physics/UDE

Major Success for the Faculty of Physics New Collaborative Research Centre

[31.05.2016] The competition was of a very high standard: Numerous groups of researchers applied for a new Collaborative Research Centre (SFB). "In view of the large, nationwide competition, we are very happy that the Deutsche Forschungsgemeinschaft opted for our application", said a very pleased Prof. Dr. Uwe Bovensiepen, Head of the Ultrafast Dynamics at Interfaces group of researchers in the Faculty of Physics of the University of Duisburg-Essen (UDE). "At the same time, this decision confirms our leading role in an important field of physics", explained the future CRC 1242 spokesperson.

The complete press release can be found here.