Magnonic Holographic Memory: From Proposal to Device

In this paper, we present recent developments in magnonic holographic memory devices exploiting spin waves for information transfer. The devices comprise a magnetic matrix and spin wave-generating/detecting elements placed on the edges of the waveguides. The matrix consists of a grid of magnetic waveguides connected via cross junctions. Magnetic memory elements are incorporated within the junction, while the read-in and read-out are accomplished by the spin waves propagating through the waveguides. We present the experimental data on spin-wave propagation through NiFe and yttrium iron garnet Y₃Fe₂(FeO₄)₃ (YIG) magnetic crosses. The obtained experimental data show prominent spin-wave signal modulation (up to 20 dB for NiFe and 35 dB for YIG) by the external magnetic field, where both the strength and the direction of the magnetic field define the transport between the cross arms. We also present the experimental data showing parallel read-out of two magnetic memory elements via spin-wave interference. The recognition between the four possible memory states is achieved via proper adjustment of the phases of the interfering spin waves. All experiments are done at room temperature. Magnonic holographic devices aim to combine the advantages of magnetic data storage with wave-based information transfer. We present estimates on the spin-wave holographic devices performance, including power consumption and functional throughput. According to the estimates, the magnonic holographic devices may provide data processing rates higher than 1 × 10¹⁸ b/cm²/s while consuming 0.15 mW. Technological challenges and fundamental physical limits of this approach are also discussed.