Universiteit Leiden

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Inducing spin triplet superconductivity in a ferromagnet

Promotor: J. Aarts

Stefano Voltan
29 september 2016
Thesis in Leiden Repository

Combining ferromagnetism and superconductivity can lead to the development of a completely new generation of technology, with unique and powerful characteristics, called superconducting spintronics. The task of developing this, however, is challenging because at the microscopic level the superconducting and ferromagnetic states are intrinsically incompatible. Under certain conditions, however, the conventional (singlet) superconducting state can be converted into the triplet one, with the spins of the electrons forming the Cooper pairs aligned parallel. The triplet state can coexist with ferromagnetism and is very interesting both for applications and from a fundamental point of view. In this thesis we study the electrical properties of small hybrid devices that mainly consist of superconducting and ferromagnetic layers. By measuring the electrical resistance of these devices as a function of parameters such as the temperature or the applied magnetic field, it is possible to indirectly infer important information about the state of the (super)conductivity in the different layers. We investigate different types of devices (multilayers, triplet spin valves and Josephson junctions), in order to address different aspects related to the generation of the triplet state, for a better and better control of the process.