2020/04/01
Keio University
Japan Science and Technology Agency (JST)
Shoma Tatsuno, a first-year master's student at the Graduate School of Science and Technology, Keio University, and Professor Yukio Nozaki of the Faculty of Science and Technology have discovered that in a composite material combining a magnet and a semiconductor, the amplitude of "spin waves," which are waves of magnetism, can be significantly modulated depending on the direction of sound wave injection and the direction of magnetization.
With conventional methods, when the magnet's thickness is reduced to the nanometer scale, the amplitudes of spin waves propagating in the forward and backward directions become equal, making it difficult to achieve rectification of spin waves.
This research group fabricated a nickel/silicon composite material (composite material) by combining a 20-nanometer-thick thin-film nickel magnet and a 400-nanometer semiconductor silicon, and demonstrated that the amplitude of backward-propagating spin waves can be reduced to less than one-twelfth of that in the forward direction.
The new composite material, for which the giant nonreciprocity of spin waves was demonstrated in this study, is expected to significantly advance the development of spin-wave diodes, which are essential for the realization of spin-wave devices that use the propagation and interference of spin waves for logical operations.
The results of this research were published online in the American Physical Society journal "Physical Review Applied" on March 31, 2020 (U.S. Eastern Time).
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