Breaking Space Inversion‐Symmetry to Obtain Asymmetric Spin‐Wave Excitation in Systems with Nonuniform Magnetic Exchange

Abstract

AbstractThe consequences of non‐uniform exchange in magnetic systems are reported. The quantum mechanical exchange interaction between spins is responsible for the phenomenon of magnetic order, and is generally considered to be uniform across bulk magnetic systems. Partly inspired by the Dzyaloshinskii‐Moriya interaction—also known as antisymmetric exchange—a linearly varying exchange interaction is used along a magnetic strip as a route to spatial inversion symmetry‐breaking. It is found that, in addition to asymmetric modes and localization, spatially varying exchange can be used to design nonreciprocal magnetic signal excitation at frequencies that are tunable. Moreover, the authors’ work predicts nonreciprocity to occur across a vast range of frequencies up to hundreds of GHz. Such spin wave engineering is a key area of ongoing research in the fields of magnonics and spintronics, which are expected to enable the next generation of wireless communication technology and information processing. Analogous nonreciprocity is expected to occur in other wave systems with gradient properties.