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TT: Fachverband Tiefe Temperaturen
TT 25: Superconductivity: Supercurrent Diode Effect
TT 25.11: Vortrag
Mittwoch, 19. März 2025, 12:15–12:30, H32
The Josephson diode effect with Andreev and Majorana states — •Sayan Mondal1, Pei-Hao Fu2, and Jorge Cayao1 — 1Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala, Sweden — 2Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
We consider a Josephson junction formed by Rashba superconductors and investigate the Josephson diode effect as the system transitions from a trivial to a topological phase under an applied external Zeeman field [1]. The component of the Zeeman field parallel to the spin-orbit axis introduces asymmetry in the Andreev bound states, which in turn leads to an asymmetry in the Josephson current, giving rise to the diode effect. In this study, we analyze the forward and backward currents, which differ due to the presence of the parallel Zeeman field. We discover that the diode's efficiency as a function of the Zeeman field exhibits a rich structure strongly dependent on the Andreev bound states. This dependence reveals clear signatures of the topological phase of transition. Notably, in the topological phase, the diode efficiency develops an oscillatory pattern reflecting Majorana bound states' formation. We have also verified that the functionality of the obtained Josephson diode is robust against finite temperatures, below the superconducting gap. Our findings help us understand the realization of Josephson diodes in topological superconductors and can also be useful for identifying the emergence of Majorana bound states.
[1] S. Mondal, P. -H. Fu, and J. Cayao, In preparation.
Keywords: Topological Superconductivity; Josephson junction; Josephson diode effect; Andreev reflections; Majorana states