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SUMMARY:IMX Talks - Interplay of Cooper Quartets\, Finite Momentum Pairing
 \, and Josephson Diode Effect in 1T Transition Metal Dichalcogenides
DTSTART:20260615T110000
DTEND:20260615T120000
DTSTAMP:20260610T215102Z
UID:b3590bed3357f5244ad8cb188bd228889181d25972b07cf3f3e93366
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Pranava Keerthi Sivakumar\, Department of Nano-systems fro
 m Ions\, Spins and Electrons(NISE)\, Max Planck Institute of Microstructur
 e Physics\, Halle\, Germany\nSupercurrent diode effects have recently attr
 acted much attention for their potential applications in superconducting l
 ogic circuits\, rectification applications and also in the study of fundam
 ental symmetries of the underlying superconducting order parameter. In thi
 s talk\, I’ll introduce the idea of finite momentum Cooper pairing (FMCP
 ) in systems with strong helical spin-momentum locking and how this can na
 turally give rise to non-reciprocity in superconducting critical currents 
 namely the Josephson diode effect (JDE). I’ll describe our work establis
 hing the presence of a large JDE due to FMCP in lateral Josephson junction
 s formed from centrosymmetric van der Waals type-II Dirac semimetals 1T-Ni
 Te2 and 1T-PtTe2. A theoretical analysis based on a Ginzburg-Landau type m
 odel suggests that the FMCP introduces a phase difference between the firs
 t (Cooper pair) and second (Cooper quartet) harmonic supercurrents\, which
  manifests as the JDE. Measurements of the JDE as a function of the in-pla
 ne magnetic field and half-flux quantum oscillations in the JDE are in goo
 d agreement with the predictions\, indicating the presence of large second
  harmonic supercurrents in the junction. Surface modifications are shown t
 o strongly enhance the supercurrents in the junction\, nearly by a factor 
 of two\, indicating the strong contribution of the topological surface sta
 tes to the supercurrent transport. Overall\, 1T systems provide an interes
 ting platform for exploring the interplay of FMCP\, JDE and topological su
 perconductivity.\n\nBio: Dr. Pranava Keerthi Sivakumar completed his Bach
 elors and Masters in Chemistry with a minor in Physics from the Indian Ins
 titute of Science\, Bengaluru\, India in 2017. He then moved to Germany wh
 ere he completed his Ph.D. at the Martin Luther University in Halle\, grad
 uating summa cum laude. During his Ph.D.\, he worked on studying the elect
 rical transport properties of materials with non-collinear spin textures a
 nd unconventional superconductivity due to strong spin-orbit coupling. Mos
 t notably during his Ph.D.\, he uncovered the role of finite momentum pair
 ing induced Josephson diode effect in topological materials with helical s
 pin-momentum. He is currently a postdoctoral researcher at the NISE depart
 ment in the Max Planck Institute of Microstructure Physics\, focusing on t
 he interplay of magnetization dynamics and supercurrent transport in super
 conductor-ferromagnet heterostructures.
LOCATION:BM 3241 https://plan.epfl.ch/?room==BM%203241
STATUS:CONFIRMED
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