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A new class of information technology, called magnonics, has been employed to develop several information-processing functionalities, such as logic gates, majority gates, and multiplexers. However, the application of these functionalities has been limited because the transmission loss of spin-wave signals makes combining these functionalities challenging. A promising technique called spin-wave soliton train was developed by experimental pioneers, however, the problem of information density was not yet overcome. In this study, a generation method of soliton train was revisited, and a 10 times larger density of spin-wave soliton train was achieved in time-domain electric experiments.

We performed a propagating spin-wave spectroscopy for backward spin-waves in ferromagnetic metallic microstructures in the presence of electric-current. Even with the smaller current injection of A m−2 into ferromagnetic microwires, the backward spin-waves exhibit a gigantic 200 MHz frequency shift and a 15% amplitude change, showing 60 times larger modulation compared to previous reports. Systematic experiments by measuring dependences on a film thickness of mirowire, on the wave-vector of spin-wave, and on the magnitude of bias field, we revealed that for the backward spin-waves a distribution of internal magnetic field generated by electric-current efficiently modulates the frequency and amplitude of spin-waves. The gigantic frequency and amplitude changes were reproduced by a micromagnetics simulation, predicting that the current-injection of A m−2 allows 3 GHz frequency shift. The effective coupling between electric-current and backward spin-waves has a potential to build up a logic control method which encodes signals into the phase and amplitude of spin-waves. The metallic magnonics cooperating with electronics could suggest highly integrated magnonic circuits both in Boolean and non-Boolean principles.

We measured magnon densities during spin-wave interference using microfocused Brillouin light scattering spectroscopy. Spatial mapping of the magnon density revealed that the spin-wave interference is confined in the central region of the microwire and indicated the contribution of higher-order transverse quantized modes than those reported to date. A micromagnetic simulation revealed transverse 100 nm interference patterns, which affect the signal-to-noise ratio of magnonic logic operation. These results will provide a way to design integrated magnonic devices such as all-magnon transistors.

We demonstrate the time-resolved real-space observation of vortex gyration in a magnetic circular disc by X-ray magnetic circular dichroism photoemission microscopy at the SPring-8 beamline BL25SU, both with and without an additional structure called a pair tag, which serves to control the magnetic curling direction. By comparing the gyration orbits of the vortices, we found that the gyration properties are dependent on the presence of the additional structure in spite of the discs having the same diameter. Furthermore, we reproduced the vortex gyration by micromagnetic simulation. The confinement potential of the vortex can be controlled by the additional structure.

Antivortex creation in a cross-shaped wire was demonstrated by using magnetoresistance and magnetic force microscopy measurements. The magnetization process was stochastic and exhibited a wide variety of magnetoresistance curves. By developing a conventional method, we have achieved electrical determination criteria to distinguish antivortex creation from many other magnetization states. The electrical criteria provide a simple method without large-scale apparatus and promote further experiments such as spin-current driven antivortex dynamics.

Spin-wave logic operation in a ferromagnetic thin film was investigated by using a three-antenna device. Binary output 1/0 signals were realized with the constructive and destructive spin-wave interference signals. It was found that the configuration of the RF antenna determines the phase of the input spin wave, which provides a control method of logic operation in spin-wave devices.