Thesis Directors: Dr. S. Mischler, Prof. R. Logé
\r\nMaterials Science and Engineering doctoral program
\r\nThesis Nr. 11821
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\r\nTo take part in the public defense, please contact directly the speaker
Thesis Directors: Dr. F.-J. Haug, Prof. C. Ballif
\r\nPhotonics doctoral program
\r\nThesis Nr. 11549
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\r\nTo take part in the public defense, please contact directly the speaker
Showcase is Lausanne’s impact innovation summit bringing together actors from academia, business and the public sector to rethink and shape the economy of tomorrow.
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\r\nProgram:
\r\nDuring the whole day, the public can visit an exhibition of 18+ solutions to restore, monitor and protect nature
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\r\n08:30 Coffee & Croissants
\r\n09:00 Welcome and Keynote by Julia Binder (Professor of Business Transformation, IMD)
\r\n09:30 Thematic Workshops and Impact Innovation Award by FIT (Fondation pour l'Innovation et la Technologie)
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\r\n12:00 Lunch Break
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\r\n13:15 Keynote speeches, fireside chats and debates starring Cyril Dion (Author and Movie Director), Christophe Champod (Rector, UNIL), and many more
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\r\n15:00 Break
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\r\n15:30 Keynote speeches, fireside chats and debates starring Emmanuel Faber (Chair, International Sustainability Standards and former CEO of Danone), Camille Etienne (author, activist and director of the NGO Avant l'Orage), and many more
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\r\n17:00 Closing ceremony
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\r\n17:30 Cocktail reception
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Supercurrent diode effects have recently attracted much attention for their potential applications in superconducting logic circuits, rectification applications and also in the study of fundamental symmetries of the underlying superconducting order parameter. In this talk, I’ll introduce the idea of finite momentum Cooper pairing (FMCP) in systems with strong helical spin-momentum locking and how this can naturally give rise to non-reciprocity in superconducting critical currents namely the Josephson diode effect (JDE). I’ll describe our work establishing the presence of a large JDE due to FMCP in lateral Josephson junctions formed from centrosymmetric van der Waals type-II Dirac semimetals 1T-NiTe2 and 1T-PtTe2. A theoretical analysis based on a Ginzburg-Landau type model suggests that the FMCP introduces a phase difference between the first (Cooper pair) and second (Cooper quartet) harmonic supercurrents, which manifests as the JDE. Measurements of the JDE as a function of the in-plane magnetic field and half-flux quantum oscillations in the JDE are in good agreement with the predictions, indicating the presence of large second harmonic supercurrents in the junction. Surface modifications are shown to strongly enhance the supercurrents in the junction, nearly by a factor of two, indicating the strong contribution of the topological surface states to the supercurrent transport. Overall, 1T systems provide an interesting platform for exploring the interplay of FMCP, JDE and topological superconductivity.
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\r\nBio: Dr. Pranava Keerthi Sivakumar completed his Bachelors and Masters in Chemistry with a minor in Physics from the Indian Institute of Science, Bengaluru, India in 2017. He then moved to Germany where he completed his Ph.D. at the Martin Luther University in Halle, graduating summa cum laude. During his Ph.D., he worked on studying the electrical transport properties of materials with non-collinear spin textures and unconventional superconductivity due to strong spin-orbit coupling. Most notably during his Ph.D., he uncovered the role of finite momentum pairing induced Josephson diode effect in topological materials with helical spin-momentum. He is currently a postdoctoral researcher at the NISE department in the Max Planck Institute of Microstructure Physics, focusing on the interplay of magnetization dynamics and supercurrent transport in superconductor-ferromagnet heterostructures.