Jean-Paul ADAM

Jean-Paul ADAM

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Jean-Paul ADAM · MMM 2020

E4-11 Electrical spectroscopy of forward volume spin waves in perpendicularly magnetized materials

Authors: M. Sushruth, U. Bhaskar, T. Devolder, J. Adam, Universite Paris-Saclay, Saint-Aubin, Île-de-France, FRANCE|M.G. Grassi, D. Stoeffler, Y. Henry, M. Bailleul, Universite de Strasbourg, Strasbourg, Alsace, FRANCE|K. Ait-Oukaci, D. Lacour, M. Hehn, Institut Jean Lamour, Nancy, Grand Est, FRANCE|K. Ait-Oukaci, Synchrotron SOLEIL, Gif-sur-Yvette, Ile-de-France, FRANCE|

Abstract Body: Spin waves (SWs) are attractive for future wave-based-computing applications since they have easy-to-tune wavelengths from the macroscopic scale to the sub-micron scale at GHz frequencies. Information can be stored in the amplitude and phase of the SWs and transported through a thin magnetic material conduit. Isotropic SWs like the forward volume spin waves (FVSW) enable for SW based transmission, and processing of information in any arbitrary direction such as logic operations 1. And, materials with both a perpendicular magnetic anisotropy (PMA) and a large magnetization-thickness product would be much preferred for FVSW applications 2. We study the potential of all-electrical inductive techniques for the spectroscopy of propagating FVSW and we apply this to the case of perpendicularly magnetized Co/Ni multilayers. We develop a one-dimensional model to account for the electrical signature of spin-wave reflection and transmission between inductive antennas and validate it with experiments. We describe the influence of the antennae geometry and of the material parameters on the lineshape of the inductive signals. For a finite damping, the broadband character of the antenna emission in the wave vector space imposes to take into account the growing decoherence of the magnetisation waves upon their spatial propagation. The transmission signal results from two contributions: (i) from propagating spin-waves leading to an oscillatory phase of the broadband transmission coefficient, and (ii) from the distant induction of ferromagnetic resonance because of the long-range stray fields of realistic antennas. Depending on the ratio of these two contributions, the transmitted signal decay may not be exponential with the propagation distance and the oscillatory character of the spin-wave phase may be hidden. Our model and its experimental validation (Fig. 1) allow to define geometrical and material specifications to be met to enable the use of forward volume spin waves as efficient information carriers.References: 1 S. Klingler et al., Applied Physics Letters, Vol. 106, p. 212406 (2015) 2 J. Han et al., Science, Vol. 366, p. 1121-1125 (2019)