講演情報
[23a-A201-9]Magnon-magnon coupling in synthetic ferrimagnets
〇(P)Aakanksha Sud3,1, Kei Yamamoto2, Kazuya Suzuki2,3, Shigemi Mizukami1,3,5, Hidekazu Kurebayashi3,1,4 (1.Tohoku Univ., 2.JAEA, 3.WPI-AIMR, 4.UCL, 5.CSIS)
キーワード：
Hybrid Magnonics、synthetic ferrimagnet、magnon-magnon coupling
Magnons are collective excitations of magnetically ordered materials. Magnons have potential for information processing and transduction because of their numerous capabilities for example – highly tunable dispersion, microwave integration, ability to interact with various excitations for example - microwave and optical photons, phonons. Of particular importance is tuning the interaction/coupling between different excitation. When the energy transfer rate of the two interacting modes surpasses the relaxation rates of individual excitation modes, the coherent coupling of the two excitations can be measured in spectra, as an avoided crossing. The coupling strength is a tunable parameter that strongly depends on magnetic parameters and magnetic field/direction.In this work, we present a systematic study of the magnon-magnon coupling in synthetic ferrimagnets. In previous work, we have shown that the two modes do not hybridise in experimental conditions where the external magnetic field is applied within the in-plane. This can be explained by their even (optical) and odd (acoustic) nature with respect to the symmetry operation of 180 degree rotation about the applied field and inter-layer moment exchange. When two magnetic layers are not identical, the even/odd nature to the symmetry operation is broken, with the spectra showing an avoided crossing. We grew a series of multilayers with different magnetic parameters and measured their frequency spectra so that we can compare the gap size in experiments with our theoretical calculations based on coupled Landau-Lifshitz-Gilbert equation at macroscopic limit in order to understand underlying mechanisms. For example, our calculations reveal dissimilar roles of bilinear and bi-quadratic exchange interactions for the size of the gap. This study sheds light on the control of magnon-magnon interactions that can be used for magnonic signal processing devices