All-optical observation and reconstruction of spin wave dispersion

• Published in: Nature communications Vol. 8; no. 1; p. 15859
• Main Authors: Hashimoto, Yusuke, Daimon, Shunsuke, Iguchi, Ryo, Oikawa, Yasuyuki, Shen, Ka, Sato, Koji, Bossini, Davide, Tabuchi, Yutaka, Satoh, Takuya, Hillebrands, Burkard, Bauer, Gerrit E. W., Johansen, Tom H., Kirilyuk, Andrei, Rasing, Theo, Saitoh, Eiji
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.06.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 132/122; 140/125; 639/301/119/1001; 639/301/930/12; 639/766/119/997; Electrons; Fourier transforms; Humanities and Social Sciences; Materials research; Methods; multidisciplinary; Neutrons; Power; Science; Science (multidisciplinary); Spectrum analysis; Tomography; Netherlands; Japan
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15859

To know the properties of a particle or a wave, one should measure how its energy changes with its momentum. The relation between them is called the dispersion relation, which encodes essential information of the kinetics. In a magnet, the wave motion of atomic spins serves as an elementary excitation, called a spin wave, and behaves like a fictitious particle. Although the dispersion relation of spin waves governs many of the magnetic properties, observation of their entire dispersion is one of the challenges today. Spin waves whose dispersion is dominated by magnetostatic interaction are called pure-magnetostatic waves, which are still missing despite of their practical importance. Here, we report observation of the band dispersion relation of pure-magnetostatic waves by developing a table-top all-optical spectroscopy named spin-wave tomography. The result unmasks characteristics of pure-magnetostatic waves. We also demonstrate time-resolved measurements, which reveal coherent energy transfer between spin waves and lattice vibrations. Observation of the entire dispersion relation for spin waves remains a challenge which prevents the full understanding of many intriguing magnetic properties. Here, the authors develop a table-top all-optical approach to map out the dispersion curve of pure-magnetostatic waves in magnetic films.