Biologically encoded magnonics

Abstract

Spin wave logic circuits using quantum oscillations of spins (magnons) as carriers of information have been proposed for next generation computing with reduced energy demands and the benefit of easy parallelization. Current realizations of magnonic devices have micrometer sized patterns. Here we demonstrate the feasibility of biogenic nanoparticle chains as the first step to truly nanoscale magnonics at room temperature. Our measurements on magnetosome chains (ca 12 magnetite crystals with 35 nm particle size each), combined with micromagnetic simulations, show that the topology of the magnon bands, namely anisotropy, band deformation, and band gaps are determined by local arrangement and orientation of particles, which in turn depends on the genotype of the bacteria. Our biomagnonic approach offers the exciting prospect of genetically engineering magnonic quantum states in nanoconfined geometries. By connecting mutants of magnetotactic bacteria with different arrangements of magnetite crystals, novel architectures for magnonic computing may be (self-) assembled.

Controlling the Oxidation of Magnetic and Electrically Conductive Solid-Solution Iron-Rhodium Nanoparticles Synthesized by Laser Ablation in Liquids

“…The oxidation of the particles takes place within the first 6-10 h after removal of acetone until a passivating layer is formed, similar to the one observed in Fe50Rh50 thin films [64]. Further studies of magnetization dynamics in array of nanoparticles including mapping of microwave excitations in the particles of different size are possible using spatially resolved FMR as well as Brillouin light scattering (BLS) [65][66][67]. The total magnetic anisotropy of nanoparticles given by a combination of shape, magnetocrystalline, including surface anisotropy contributions, has been shown to be effectively describable by a uniaxial anisotropy field B A = 2K e f f M s , where K e f f is the effective anisotropy constant and M s is the saturation magnetization.…”

“…The oxidation of the particles takes place within the first 6-10 h after removal of acetone until a passivating layer is formed, similar to the one observed in Fe 50 Rh 50 thin films [64]. Further studies of magnetization dynamics in array of nanoparticles including mapping of microwave excitations in the particles of different size are possible using spatially resolved FMR as well as Brillouin light scattering (BLS) [65][66][67]. As an outlook for future applications, these particles with minimized oxidation are used for nanostrand formation in a transparent polymer (Figure 9) to combine the magnetic response and the electrical conductivity of the nanoalloy to tune the electrical conductivity of the polymer [11,68].…”

Spin- and Angle-Resolved Spectroscopy and Spin Waves in Biogenic Magnonic Systems

“…Zingsem et al, 2019 described the use of biogenic nanoparticle chains of bacteria Magnetospirillium gryphiswaldense (strain MSR-1, wildtype) to nanoscale magnonics at room-temperature [3]. The ferromagnetic resonance spectra (FMR) of the magnetosome chain shows magnonic band gaps and also that geometry of magnetosome chain, which depends on the genotype of the bacteria, determines band structure (confirming their magnonic nature).…”

“…Phase and amplitude are uniform within a given particle, with red hue indicating resonant response (90° phase relative to excitation) and cyan hue indicating opposite-toresonant response. Reprinted with permission from [3]. Copyright © 2019 Benjamin W. Zingsem et al…”

Electromagnonic crystals based on ferrite–ferroelectric–ferrite multilayers

“…Artificial magnetic materials with a spatial periodic modulation of their physical properties or geometry, known as magnonic crystals (MCs), are promising for a new microwave and spintronic devices [1–4]. These MCs possess desirable band gaps that appeared due to the Bragg reflection.…”