Seminar Announcement: Spin-Wave Spectrum Analysis in Ferromagnetic Disks

The SPINTEC laboratory will host a seminar on February 6, 2026, featuring Kei Yamamoto, a visiting researcher from the Advanced Science Research Center at the Japan Atomic Energy Agency. The presentation, titled "Spin-wave spectrum in a ferromagnetic disk," will begin at 11:00.

Event Details:

* Location: IRIG/SPINTEC, Auditorium 445, CEA Building 10.05 in Grenoble. Important: Physical access requires an entry authorization, which must be requested by January 27, 2026, via email at admin.spintec@cea.fr.

* Virtual Access: The seminar will also be streamed via Zoom.

* Link: https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09

* Meeting ID: 987 6986 7024

* Passcode: 025918

Seminar Focus:

The talk will address a core challenge in spintronics: how the transfer of angular momentum in its various forms leads to the loss of information carried by dynamic spin polarizations. Yamamoto will present detailed microwave spectrum measurements of magnetic excitations within a Yttrium Iron Garnet (YIG) disk.

A key part of the discussion will focus on interpreting the complex array of observed spectral lines and their dependence on magnetic fields. The analysis leverages the axial symmetry of the experimental setup, which allows spin wave modes to be classified by their conserved total angular momentum.

The measured frequency spectrum in a magnetically saturated state will be compared against analytical models—specifically, pure exchange and pure dipolar models—under conditions where different types of spectral degeneracy are expected. The experimental data reveals splittings within these theoretically degenerate modes. Yamamoto will explore potential interpretations of these splittings in the context of angular momentum transfer between different physical forms.

Speaker Background:

Kei Yamamoto is a theoretical physicist specializing in the dynamical properties of magnetic materials, applying theoretical and mathematical frameworks informed by his background in high-energy physics. He earned his PhD in General Relativity and Cosmology from the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, UK. He currently holds the position of Assistant Principal Researcher at the Japan Atomic Energy Agency's Advanced Science Research Center. His publication record is accessible via Web of Science (Author ID: OGR-4892-2025).

We are pleased to welcome Kei YAMAMOTO from Advanced Science Research Center, Japan Atomic Energy Agency. He is a visiting researcher in SPINTEC for the past few months and will give us a seminar on Friday February 06th 2026 at 11:00 entitled : Spin-wave spectrum in a ferromagnetic disk

Place : IRIG/SPINTEC, auditorium 445 CEA Building 10.05 (presential access to the conference room at CEA in Grenoble requires an entry authorization. Request it before January 27th at admin.spintec@cea.fr)

video conference : https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09

Meeting ID: 987 6986 7024

Passcode: 025918

Abstract : Angular momentum transfer in all forms contributes to the loss of information carried by dynamical spin polarisations and constitutes an important fundamental problem in spintronics. In this talk, we present a detailed microwave spectrum measurement of magnetic excitations in an Yttrium Iron Garnet disk, and how one can make sense of the multitudes of spectral lines and their magnetic field dependence theoretically. We explain how the axial symmetry of the setup leads to labelling of modes in terms of the conserved total angular momentum of the spin waves, The frequency spectrum in the saturated state is compared to analytical solutions for pure exchange as well as pure dipolar models under certain limits where different types of spectral degeneracy occur. The experimental result shows splittings of those degenerate modes, and we discuss possible interpretations in relation to angular momentum transfer between its different forms.

Biography : biography: Kei Yamamoto is a theoretical physicist working on theoretical and mathematical aspects of understanding dynamical properties of magnetic materials, leveraging his background in high energy physics. He received his PhD in General Relativity and Cosmology from the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK, and currently works as an Assistant Principal Researcher in Advanced Science Research Center, Japan Atomic Energy Agency.

bibliography : https://www.webofscience.com/wos/author/record/OGR-4892-2025

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