Exchange magnons are essential for unprecedented miniaturization of GHz electronics and magnon-based logic. However, their efficient excitation via microwave fields is still a challenge. Current methods including nanocontacts and grating couplers require advanced nanofabrication tools which limit the broad usage. Here, we report efficient emission and detection of exchange magnons using micron-sized coplanar waveguides (CPWs) into which we integrated ferromagnetic (m) layers. We excited magnons in a broad frequency band with wavelengths λ down to 100 nm propagating over macroscopic distances in thin yttrium iron garnet. Applying time-and spatially resolved Brillouin light scattering as well as micromagnetic simulations we evidence a significant wavelength conversion process near mCPWs via tunable inhomogeneous fields. We show how optimized mCPWs can form microwave-tomagnon transducers providing phase-coherent exchange magnons with λ of 37 nm. Without any nanofabrication they allow one to harvest the advantages of nanomagnonics by antenna designs exploited in conventional microwave circuits.

Topologically protected magnetic skyrmions have raised interest for future spintronics applications. One of the main challenges is the synthesis of room temperature skyrmion-hosting materials that are compatible with thin-film technology. We present an approach to produce strain-free epitaxial thin films of Co10–x Zn10–y Mn x+y using molecular beam epitaxy. Bulk Co10–x Zn10–y Mn x+y is known to host skyrmions at room temperature for specific composition ratios. Our substrate consists of graphene on oxidized silicon. The van der Waals interactions of the grown material with graphene prevents covalent bonding and corresponding strain. We show how defects in the graphene foster nucleation that results in three different kinds of morphologies: islands, columns, and merged films. Susceptibility measurements suggest a phase transition close to room temperature. We detect up to three spin waves resonances suggesting relatively low magnetic damping. This growth technique opens a new route for the integration of complex alloys and skyrmionic device concepts with silicon electronics.

Structural properties of various FeGex compounds are explored by Raman spectroscopy in order to provide reference Raman spectra, and enable fast and local phase determination in FeGe thin films.

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