Bogoliubov Laboratory of Theoretical Physics

Seminar “Theory of Condensed Matter”

Date and Time: Tuesday, 19 November 2024, at 4:00 PM

Venue: Blokhintsev Lecture Hall, Bogoliubov Laboratory of Theoretical Physics, online on Zoom

Link to join online

1. Seminar topic: «Magnetisation dynamics of a coupled system of nanomagnet and Josephson junction »

   Speaker: Muhammad Sameh (Cairo University)

   Abstract:
   

   Josephson structures with a ferromagnet offer a way to manipulate its magnetic moment dynamics employing the interplay between magnetisation and Josephson phase in such systems. This leads to a non-vanishing zero-phase Josephson supercurrent due to the existence of an anomalous ground state phase shift. In this talk, the influence of Josephson current on dynamical precession in a nanomagnet and its orientation is addressed. The effect of external drive on the coupled system considering the quasiparticle current is covered. The results obtained may deepen the knowledge of effects appearing in superconducting spintronic devices and open new perspectives for the control and manipulation of magnetisation in such devices.




2. Seminar topic: «Josephson diode effect in superconductors: a review of theory»

   Speaker: Aliasghar Janalizadehjavan (Institute for Advanced Studies in Basic Sciences, Iran)

   Abstract:
   

   The Josephson diode effect (JDE) is a novel behaviour in superconducting devices where electric current flows in one direction differently than the other, similar to a conventional diode but in superconductors. This effect relies on breaking certain symmetries in the superconducting system, such as inversion and time-reversal symmetry. In the presentation the speaker talk about how asymmetry in superconducting quantum interference devices (SQUIDs) and Josephson junctions (JJs) can produce the JDE. In additionб the speaker will discuss systems where symmetry breaking occurs and examine configurations that can lead to Josephson diodes. One of these configurations is the layering of the Josephson middle layer, which is obtained by adding a ferroelectric layer in the vicinity of a ferromagnetic layer to a diode. In addition, there will be a discussion on a system consisting of two superconductors (SQUID) in which current in one of the junctions includes the second harmonic, and this second harmonic, combined with the current of the second junction, leads to diode behaviour in the SQUID.