On Tuesday, October 17^th 2023, we have the pleasure to welcome in SPINTEC Thierry Valet. He will give us a seminar at 14:00 entitled :

Magnon Angular Momenta

Place : IRIG/SPINTEC, auditorium 445 CEA Building 10.05 (access to CEA (*))

Zoom Link : https://cnrs.zoom.us/j/94159711060?pwd=SFNxRzhYcVZvOCtLOFE1R0s5RXcrUT09
Meeting ID: 941 5971 1060
Passcode: EUU5uB

Abstract : The spin and orbital angular momenta carried by different types of waves e.g., electromagnetic, elastic, fluid or even gravitational waves, have been increasingly recognized as properties of both fundamental and practical importance over the recent decades, specially in the case of light waves [1]. It was theoretically established long ago [2] that cylindrical spin-waves, in a uniformly saturated infinite ferromagnet, carry a conserved and quantized total angular momentum, with the dynamic dipole-dipole interaction inducing magnon spin-orbit coupling (mSOC); and in recent years experimental evidences of angular momentum transfer between spin-waves and optical vortices [3, 4] or elastic waves [5, 6] have emerged. In this talk, we will discuss : (i) how the spin and orbital angular momenta of spin-waves are well defined quantities in a broad class of finite systems i.e., axisymmetric ferromagnets, which includes systems of special experimental and technological relevance such as YIG spheres and mesoscopic thin film disks, (ii) how the cylindrical symmetry enables the development of a general formal theory of mSOC, and of numerical micromagnetic solvers exhibiting remarkable accuracy and performance, and finally (iii) how magnetic resonance force microscopy measurements of a micron sized YIG disk quantitatively agree with the predicted spectral signature of mSOC in this system.

1. Franke-Arnold, S. Nat. Rev. Phys. 2022, 4, 361.
2. Tsukernik, V. JETP 1966, 23, [Zh. Eksp. Teor. Fiz., 50(6), 1631 (1966)], 1085.
   Osada, A.; Hisatomi, R.; Noguchi, A.; Tabuchi, Y.; Yamazaki, R.; Usami, K.; Sadgrove, M.;
3. Yalla, R.; Nomura, M.; Nakamura, Y. Phys. Rev. Lett. 2016, 116, 223601.
4. Sharma, S.; Blanter, Y. M.; Bauer, G. E. W. Phys. Rev. B 2017, 96, 094412.
5. An, K. et al. Phys. Rev. B 2020, 101, 060407.
6. Xu, M.; Yamamoto, K.; Puebla, J.; Baumgaertl, K.; Rana, B.; Miura, K.; Takahashi, H.; Grundler,
7. D.; Maekawa, S.; Otani, Y. Science Advances 2020, 6, eabb1724.

(*) Access to CEA requires an entry authorization. request it sufficiently in advance : before October 07^th  at admin.spintec@cea.fr