Magnonics investigates spin waves—collective excitations of the spin system in magnetically ordered media—as prospective information carriers beyond conventional electronics. The first lecture, “Fundamentals and Bose–Einstein Condensation”, will introduce the essential principles of spin-wave dynamics, dispersion, and nonlinear interactions. Experimental approaches such as parametric pumping and microfocused Brillouin light scattering will be discussed as powerful tools for populating and probing spin-wave spectra. Particular emphasis will be placed on the realization of magnon Bose–Einstein condensation (BEC) in magnetic insulators, most notably in yttrium iron garnet (YIG), where thermalization and overpopulation of magnons give rise to condensates observable at room temperature. This part will provide a conceptual and experimental framework for understanding condensate formation in solid-state bosonic systems. The second lecture, “Magnonic Supercurrents, Accumulation Phenomena, Applications in Data Processing”, will expand the discussion toward macroscopic transport and collective states beyond conventional condensation. A central theme will be the phenomenon of quasiparticle accumulation, which generalizes the notion of condensation by enabling spontaneous, but not necessarily coherent, population of distinct spectral regions. In particular, the magnon–phonon interaction produces hybrid magnetoelastic modes and can lead to bottleneck accumulation of quasiphonons and quasimagnons with different propagation characteristics. Such accumulation phenomena extend the diversity of many-body states in driven magnetic systems, providing new perspectives on transport, localization, and hybridization. The lecture will conclude with an outlook on magnon supercurrents, Bogoliubov waves, and the prospective use of condensates and accumulation regimes in magnonic devices for data processing, information storage, and hybrid quantum technologies.

• Thematic program: Mathematics – Magnetism - Materials (2025/2026)
• Event: Minicourse "Magnon Macroscopic Quantum States" by Burkard Hillebrands (2025)

Magnonics investigates spin waves—collective excitations of the spin system in magnetically ordered media—as prospective information carriers beyond conventional electronics. The first lecture, “Fundamentals and Bose–Einstein Condensation”, will introduce the essential principles of spin-wave dynamics, dispersion, and nonlinear interactions. Experimental approaches such as parametric pumping and microfocused Brillouin light scattering will be discussed as powerful tools for populating and probing spin-wave spectra. Particular emphasis will be placed on the realization of magnon Bose–Einstein condensation (BEC) in magnetic insulators, most notably in yttrium iron garnet (YIG), where thermalization and overpopulation of magnons give rise to condensates observable at room temperature. This part will provide a conceptual and experimental framework for understanding condensate formation in solid-state bosonic systems. The second lecture, “Magnonic Supercurrents, Accumulation Phenomena, Applications in Data Processing”, will expand the discussion toward macroscopic transport and collective states beyond conventional condensation. A central theme will be the phenomenon of quasiparticle accumulation, which generalizes the notion of condensation by enabling spontaneous, but not necessarily coherent, population of distinct spectral regions. In particular, the magnon–phonon interaction produces hybrid magnetoelastic modes and can lead to bottleneck accumulation of quasiphonons and quasimagnons with different propagation characteristics. Such accumulation phenomena extend the diversity of many-body states in driven magnetic systems, providing new perspectives on transport, localization, and hybridization. The lecture will conclude with an outlook on magnon supercurrents, Bogoliubov waves, and the prospective use of condensates and accumulation regimes in magnonic devices for data processing, information storage, and hybrid quantum technologies.

• Thematic program: Mathematics – Magnetism - Materials (2025/2026)
• Event: Minicourse "Magnon Macroscopic Quantum States" by Burkard Hillebrands (2025)