Fig. 2: Physical principle of the phonon-magnon reservoir.
From: On-chip phonon-magnon reservoir for neuromorphic computing
a Calculated dependences of the frequencies of the nanograting magnon modes on magnetic field. Blue solid lines show the 6 lowest modes (forming the S-band). The external magnetic field, B, is applied in the layer plane at 45o angle relative to the NG edge. The spectral range of the 1st order W-band is shown by the pink dashed rectangle. The vertical dashed line shows the magnetic field strength at which the spectral centres of the S- and W-bands coincide. b Calculated spatial profiles of the 22 W-modes (normalized absolute value of displacement vector, exaggerated for clarity) and 6 lowest S-modes in the ferromagnetic layer (z-projection of the normalized magnetization). c Coordinate system and relative positions of the write and read spots in the experiments. d Noise-free readout signals measured for three values of B at 20-µm distance between the write and read spots. e Colour map showing the field dependence of the spectral amplitude obtained by a fast Fourier transform of the readout signals measured at X0 = 20 µm. The vertical dashed line shows the magnetic field strength, at which the magnon readout demonstrates the most complex waveform. The horizontal dashed lines indicate the calculated spectral position of the guided phonon W-band. f, g Typical magnon noise-free readouts measured at various horizontal (f) and vertical (g) relative shifts of the write and read spots. Left panels show the transient signals, right panels the respective fast Fourier transforms. Time t = 0 corresponds to the moment when the input laser pulse hits the ferromagnetic layer.
