Arbeitsgruppe Prof. Hillebrands

Welcome to the magnetism group!

We are dedicated to cutting-edge research in the field of magnonics and related areas combined with excellent teaching.

Magnonics is a subfield of spintronics, which addresses the utilization of the spin degree of freedom for applications in information and communication technologies. We study „magnetic waves“, which are spin waves and their quanta called magnons, and we address new fundamental phenomena and their potential for applications. A particular focus is on macroscopic quantum phenomena such as supercurrents and their utilization, as well as on the development of magnonic devices for the information technology.

Our research is embedded in the Collaborative Research Center 173 „Spin+X“ funded by the Deutsche Forschungsgemeinschaft, as well as by several national, European and international projects. We offer opportunities for qualification in the frames of student assistantships, bachelor, master diploma and PhD projects in an international environment.

News

02-2024

Our article "Persistent magnetic coherence in magnets" has been published in Nature Materials

When excited, the magnetization in a magnet precesses around the field on a timescale governed by viscous magnetization damping, after which any information carried by the initial actuation seems to be lost. This damping appears to be a fundamental bottleneck for the use of magnets in information processing. However, here we demonstrate the recall of the magnetization-precession phase after times that exceed the damping timescale by two orders of magnitude using dedicated two-colour microwave pump–probe experiments for an YIG microstructured film. Time-resolved magnetization state tomography confirms the persistent magnetic coherence by revealing a double-exponential decay of magnetization correlation. We attribute persistent magnetic coherence to a feedback effect, that is, coherent coupling of the uniform precession with long-lived excitations at the minima of the spin-wave dispersion relation. Our finding liberates magnetic systems from the strong damping in nanostructures that has limited their use in coherent information storage and processing.
See Publication

01-2024

Our papers "Bose-Einstein condensation in systems with flux equilibrium" and "Towards an experimental proof of the magnonic Aharonov-Casher effect" have been selected for Editors’s Suggestions in Physical Review B

Quasiparticles, created in dissipative nonlinear wave systems by external excitation, can form a Bose-Einstein condensate. In this article, we describe the physical phenomena and conditions leading to condensation in various regimes of external excitation from weak and stationary to ultrastrong pumping. We have developed a stationary nonlinear theory of kinetic instability for the latter, supported by the experimental data for magnons, parametrically pumped in roomtemperature films of yttrium iron garnet.

Phys. Rev. B 109, 014301 (2024)

The Aharonov-Casher effect is the accumulation of the wave function phase when a particle with magnetic moment passes through an electric field. This phenomenon is observed for real particles and predicted for quasiparticles such as magnons. In this letter, we investigate the impact of a strong electric field on the phase of dipolar spin waves exited in a ferromagnetic yttrium iron garnet (YIG) film and report the experimental results in favor of the magnonic Aharonov-Casher effect.

Phys. Rev. B 108, L220404 (2023)

Recent Publications

Persistent magnetic coherence in magnets
T. Makiuchi, T. Hioki, H. Shimizu, K. Hoshi, M. Elyasi, K. Yamamoto, N. Yokoi, A. A. Serga, B. Hillebrands, G. E. W. Bauer, and E. Saitoh
Nature Materials (2024)

Anisotropy-assisted magnon condensation in ferromagnetic thin films
T. Frostad, P. Pirro, A.A. Serga, B. Hillebrands, A. Brataas, and A. Qaiumzadeh
Phys. Rev. Res. 6, L012011 (2024)

Bose–Einstein condensation in systems with flux equilibrium
V. S. L’vov, A. Pomyalov, S. V. Nazarenko, D. A. Bozhko, A. J. E. Kreil, B. Hillebrands, and A. A. Serga
Phys. Rev. B 109, 014301 (2024)

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