Symmetry Breaking in One- andTwo-Dimensional Semiconductor/Ferromagnetic-Insulator/Superconductor Hybrids

PhD defence by Junting Zhao

Assessment Committee

Professor Jesper Nygård, Niels Bohr Institute, University of Copenhagen (Chairperson)
Professor Elke Scheer, University of Konstanz
Professor Andrea Hofmann, University of Basel

Supervisors

Associate Professor Saulius Vaitiekenas

Department

Niels Bohr Institute

Place

The defence is conducted as a hybrid defence.

To attend the defence in person:
Building: A, Room: Aud A, Blegdamsvej 17, 2100, Copenhagen Ø

To attend the defence online:
Please follow the link to attend the defence online: https://ucph-ku.zoom.us/j/62982570328?pwd=xsahmOakZAGDpmPabf9gZc3jYHm4d9.1
MeetingID, if relevant: 629 8257 0328
Password, if relevant: 740960

Email address to gain access to the thesis: junting.zhao@nbi.ku.dk.
You will either receive a copy of the thesis or be informed where you can read a physical copy.
Recipients of copies of the thesis are not allowed to share or distribute it due to copyright compliance.

Short description of the thesis

This thesis begins with a simple question: what happens when magnetism and superconductivity, two effects that normally work against each other, are brought together? To find out, we combine ferromagnetic, superconducting, and semiconducting materials in nanoscale devices and cool them to extremely low temperatures. We observe that the devices reveal new behaviours, including superconducting currents that flow differently in opposite directions; that is, it behaves like a superconductor diode. The experiments move from one-dimensional nanowires that we used as prototypes to scalable two-dimensional material systems, showing how magnetism can affect superconductivity. These findings offer new possibilities for spintronics and future quantum technologies.