Inverse design optimization and experimental study of magnon circuits for room- and cryogenic-temperature applications
by
Andrey Voronov
Abstract
Magnonics uses collective excitations of the magnetization (spin waves) as energy-efficient information carriers and is a promising route beyond CMOS technology. This thesis advances spin-wave-based computing at both room and cryogenic temperatures by addressing three key challenges.
First, a new inverse-design framework is developed that combines micromagnetic simulations, level-set parametrization, and the adjoint-state method to automatically design functional spin wave devices. It successfully produces a compact frequency-selective spin-wave demultiplexer in a 1 μm x 1 μm region.
Second, the thesis demonstrates that gallium-doped YIG (Ga:YIG) nanowaveguides support exchange-dominated spin waves with group velocities several times higher than in undoped YIG, establishing Ga:YIG as a strong candidate for nanoscale magnonic circuits.
Third, a hybrid Maxwell–micromagnetics simulation scheme is introduced to quantify and compensate substrate-induced stray fields in YIG/GGG heterostructures at millikelvin temperatures, providing essential input for future quantum magnonics devices.
Defense committee:
Sebastian van Dijken, Alto University, FI (reviewer)
Riccardo Hertel, Université de Strasbourg, FR (reviewer)
Claas Abert (supervisor)
Andrii Chumak (supervisor)
Thomas Pichler (chair)