Electrical Manipulation of Spin Dynamics in Ferromagnetic Multi-layers

This thesis explores spin-detection in ferromagnetic materials via two different mechanisms that drive the ferromagnetic resonance – the charge-spin conversion via inverse spin-Hall effect induced by an external charge current and the photon-magnon coupling between ferromagnetic structures and superconducting microwave resonators. The investigation of the first mechanism involves mapping the magnetic properties of two ferromagnetic materials (FeAlSi and YIG), studying the various torques present in the ferromagnets and examining the temperature dependence of a ferromagnet/superconductor heterostructure. FeAlSi Hall bars fabricated on 10 nm-thick FeAlSi films grown on a MgO substrate are characterized by performing current-induced ferromagnetic resonance measurements to extract magnetic anisotropy and magnetic damping at room temperature. On the other hand, Hall bars patterned on YIG/Nb bilayers are studied by conducting spin pumping experiments in order to explore the magnetic dynamics with a focus on investigating the evolution of the rectified DC voltage with respect to temperature. The investigation of the second mechanism centres on the simulation-based optimization of the low-impedance microwave resonators fabricated from 80 nm-thick Nb layers on 430 µm thick sapphire substrates and the various coupling effects present in the system. The simulation results are analysed using an equivalent circuit model to extract electrical parameters, including capacitance, inductance and impedance, which are then considered to predict the behaviour of the resonant structures. Although the coupling systems have not yet been characterized when this thesis is finished, an analytical model is given on the ferromagnetic resonance behaviours of the coupled system.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2025

Author dc:creator

• Huang, Ruizhi

Advisor dc:contributor.advisor

• Ciccarelli, Chiara

• Spintronics
• Ferromagnetism
• Superconductivity

Licence

• https://www.repository.cam.ac.uk/bitstreams/9af3ad83-a105-4b3e-ab22-4152f1baaae4/download
• http://purl.org/NET/rdflicense/allrightsreserved

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.124728

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/395093