Leiden University Student Repository

Woltjes, Bart (2019)

Characterising Spin-triplet Josephson Junctions using Quantum Interferometry and Shapiro Steps

Master thesis | Physics (MSc)

This work presents a study of two types of spin-triplet Josephson junctions that are characterised by superconducting quantum interference and Shapiro step measurements. The first type of system is a cobalt/niobium disk where long-range triplets are generated by the spin texture of a ferromagnetic vortex. The second system is a mesoscopic ring of Sr2RuO4, which is expected to host intrinsic Josephson junctions by the presence of chiral domain walls. For the cobalt/niobium disk, two supercurrent channels have been found surprisingly close to the edges of the disk by quantum interferometry measurements while indications of 0-pi segments have been found by the observation of half-integer Shapiro steps. Two rings with different inner and outer radii of Sr2RuO4 are shown to behave as Josephson junctions. The configurations of these junctions depend on the ring dimensions and the temperature. These findings make a convincing case for the presence of chiral domains in Sr2RuO4.

spin-triplet

superconductivity

josephson junction

shapiro steps

quantum interferometry

Sr2RuO4

cobalt

ferromagnet

Author

Woltjes, Bart

Faculty

Faculty of Science

Specialisation

QMO

Supervisors

Aarts, Jan

ECTS Credits

5

Language

en