Vážené kolegyne a kolegovia,
radi by sme Vás pozvali na ďalší z cyklu ústavných seminárov. Seminár sa uskutoční vo veľkej zasadačke (miestnosť 101) v STREDU 16. 9. 2026 o 10:00 a tentokrát bude prezentovať:
Assoc. Professor Satoshi Tomita
Tohoku University, Sendai, Japan
Magnetic Metamaterials: From Static to Dynamic
Abstrakt:
In this seminar, I will introduce our recent progress in magnetic metamaterials research. In the first part, our work on static magnetic metamaterials will be discussed [1]. In particular, I will focus on a magnetochiral metamolecule consisting of a magnetic YIG rod embedded in a Cu chiral helix. This metamolecule supports a nonreciprocal magnon-polariton, in which magnons in the YIG are ultrastrongly coupled to microwave photons at GHz frequencies captured in the Cu helix cavity at room temperature [2-3]. I will also introduce a magnetochiral metasurface operating at GHz frequencies [4]. In the second part, I will present our brand-new research on dynamic magnetic metamaterials. In these metamaterials, the magnetic permeability of Permalloy is dynamically modulated at GHz frequencies [5-7]. The time-varying permeability gives rise to microwave frequency conversion through nonlinear magnetization dynamics [7]. This work opens a new direction for magnetic metamaterials, in which their electromagnetic properties can be dynamically controlled in time.
[1] ST et al., „Metamaterials with magnetism and chirality“, J. Phys. D: Appl. Phys. 51, 083001 (2018).
[2] K. Mita et al., „Ultrastrongly coupled and directionally nonreciprocal magnon polaritons in magnetochiral metamolecules“, Phys. Rev. Appl. 23, L011004 (2025).
[3] K. Mita et al., „Microwave one-way transparency by large synthetic motion of magnetochiral polaritons in metamolecules“, Phy. Rev. B 113, L121406 (2026).
[4] T. Kodama et al., „Pure moving optical media consisting of magnetochiral metasurfaces“, Opt. Mater. Expr. 14, 2499 (2024).
[5] T. Kodama et al., „Spin-current Driven Permeability Variation for Time-varying Magnetic Metamaterials“, Phys. Rev. Appl. 19, 044080 (2023).
[6] T. Kodama et al., „Direct observation of current-induced nonlinear spin torque in Pt-Py Bilayers“, Phys. Rev. B 109, 214419 (2024).
[7] T. Kodama et al., „Magnetic permeability time-varying metamaterials at microwave frequencies“, Opt. Mater. Expr. 16, 2875 (2026).
Tešíme sa na Vás.