Master's Thesis
Phase-resolved Brillouin light scattering: development and applications
Final Thesis 11 MBAuthor of thesis: Ing. Ondřej Wojewoda, Ph.D.
Acad. year: 2019/2020
Supervisor: Ing. Michal Urbánek, Ph.D.
Reviewer: doc. Mgr. Adam Dubroka, Ph.D.
Abstract:Spin waves have the potential to be used as a new platform for data transfer and processing as they can reach wavelengths in the nanometer range and frequencies in the terahertz range. To be able to design the spin-wave devices and logic circuits we need to be able to gather the information about spatial distribution of the spin-wave intensity and if possible, also their phase. This can be measured with the use of phase-resolved micro-Brillouin-light-scattering (µ-BLS) setup. The presented work deals with extending the existing intensity resolved setup with the possibility to also acquire the spin-wave phase. The upgraded Brillouin light scattering setup is thoroughly described and its performance is characterized. The capabilities of the developed setup are demonstrated in the study of propagation of spin waves through a Néel domain wall. The acquired 2D spin-wave intensity maps reveal that spin-wave transmission through a domain wall is influenced by a topologically enforced circular Bloch line in the domain wall center and that the propagation regime depends on the spin-wave frequency. In the first regime, two spin-wave beams propagating around the circular Bloch line are formed, whereas in the second regime, spin waves propagate in a single central beam through the circular Bloch line. Phase-resolved µ-BLS measurements reveal a phase shift upon transmission through the domain wall for both regimes. Micromagnetic modelling of the transmitted spin waves unveils a distortion of their phase fronts which needs to be taken into account when interpreting the measurements and designing potential devices. Moreover, we show, by means of micromagnetic simulations, that an external magnetic field can be used to move the circular Bloch line within the domain wall to manipulate spin-wave propagation.
magnonics, spin wave, light scattering, optical setup, Brillouin light scattering
Date of defence
13.07.2020
Result of the defence
Defended (thesis was successfully defended)
Grading
A
Process of defence
Po otázkách oponenta bylo dále diskutováno: Stokesův a anti-Stokesův rozptyl na magnonech. Grupová rychlost. Student otázky zodpověděl.
Language of thesis
English
Faculty
Department
Study programme
Applied Sciences in Engineering (M2A-P)
Field of study
Physical Engineering and Nanotechnology (M-FIN)
Composition of Committee
prof. RNDr. Tomáš Šikola, CSc. (předseda)
prof. RNDr. Miroslav Liška, DrSc. (místopředseda)
prof. RNDr. Bohumila Lencová, CSc. (člen)
prof. RNDr. Jiří Komrska, CSc. (člen)
prof. RNDr. Petr Dub, CSc. (člen)
prof. RNDr. Radim Chmelík, Ph.D. (člen)
prof. RNDr. Jiří Spousta, Ph.D. (člen)
doc. Ing. Radek Kalousek, Ph.D. (člen)
prof. RNDr. Pavel Zemánek, Ph.D. (člen)
RNDr. Antonín Fejfar, CSc. (člen)
Supervisor’s report
Ing. Michal Urbánek, Ph.D.
Grade proposed by supervisor: A
Reviewer’s report
doc. Mgr. Adam Dubroka, Ph.D.
Grade proposed by reviewer: A