Spin dynamics in laterally patterned magnetic landscapes with ferromagnetic/paramagnetic interfaces

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The transition metal alloys whose magnetic properties are sensitive to structural disordering offer a unique opportunity for fabrication of laterally patterned magnetic nanostructures. Such artificial magnetic landscapes with periodical distribution of adjacent ferromagnetic (FM) and paramagnetic (PM) areas are promising for exploitation of nanoscale spin-dependent phenomena. They can be created using ion beam irradiation of the Fe60Al40 alloy. This material is paramagnetic in the B2 structurally ordered state while the disordering and transition to A2 (or bcc) structure induces ferromagnetism, which makes it possible to perform lateral patterning via ion irradiation through mask templates. Within the suggested 36-months project we offer to investigate the magnetic state, magnetization reversal and spin dynamics of such FeAl-based lateral nanostructures and address the phenomena arising at periodical FM-PM interfaces. We offer to use a multifrequency Ferromagnetic Resonance (FMR) technique for the investigation of the spin dynamics. The first part of project is devoted to bilayer structures where understanding the properties of FeAl acting as spin sink and spin source in PM and FM states, correspondingly, will be achieved as well as the role of the magnetic interface will be analyzed. Then, laterally patterned nanostructures produced by ion irradiation through lithographic masks as well as self-assembled monolayers of polystyrene nanoparticles will be addressed. Analysis of static magnetic properties such as magnetization, coercivity, anisotropy depending on the structural and size parameters of embedded FM nanostructures will be performed in order to understand the results of the spin dynamics study. In particular, our research is aimed to the revealing of lateral spin pumping governed by the generation of an angular momentum current at the FM-PM interface, and spin-sink driven excitation of magnetic moment which was observed so far only in magnetic multilayers. We will perform a systematic study of magnetic damping in such novel systems with periodical modulation of magnetic properties within the thin films, taking into account the influence of two-magnon scattering processes. This project will shed some light to the specificity of phenomena occurring in lateral structures with vertical FM/PM interfaces and serve as a base for further exploitation of complex artificial magnetic landscapes in spintronics and magnonics.