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We experimentally demonstrate the operation of a Rowland-type concave grating for spin waves, with potential application as a microwave spectrometer. In this device geometry, spin waves are coherently excited on a diffraction grating and form an interference pattern that focuses spin waves to a point corresponding to their frequency. The diffraction grating was created by focused-ion-beam irradiation, which was found to locally eliminate the ferrimagnetic properties of YIG, without removing the material. We found that in our experiments spin waves were created by an indirect excitation mechanism, by exploiting nonlinear resonance between the grating and the coplanar waveguide. Although our demonstration does not include separation of multiple frequency components, since this is not possible if the nonlinear excitation mechanism is used, we believe that using linear excitation the same device geometry could be used as a spectrometer. Our work paves the way for complex spin-wave optic devices—chips that replicate the functionality of integrated optical devices on a chip-scale. [ABSTRACT FROM AUTHOR]

In this paper, we show the feasibility of tuning both the location of domain wall nucleation and the required nucleation field by changing the geometry of nanomagnets using shadowing effects. The perpendicular anisotropy is locally reduced by shadowing effects during sputter deposition. A 3-D model based on experimental measurements of fabricated nanomagnets has been developed. Experimental data from atomic force microscopy measurements and anisotropy measurements of fabricated Co/Pt-nanomagnets allow to realistically model the anisotropy and geometry of the nanomagnets. Micromagnetic simulations based on the developed 3-D model have been performed. It is shown that increasing the undercut in the resist decreases the switching field of the nanomagnets. By varying the tip geometry of the nanomagnet, the switching field can be further decreased, and subsequently, the nucleation point can be controlled, making this technique feasible for the use in perpendicular nanomagnetic logic circuitry. [ABSTRACT FROM AUTHOR]

In recent years magnetic skyrmions attracted great attention for the possibility to move them with low current density, their intrinsic stability and their robustness against defects and edge roughness compared to other magnetic textures. For applications, it is very important to be able to influence the behaviour of skyrmions locally. In this article, we present an evaluation on the effects of FIB Ga+ irradiation on skyrmion motion in W/CoFeB/MgO thin films. The influence of FIB irradiation is evaluated both, in terms of modification of the skyrmion Hall angle and the skyrmion velocity. An overview of the effects of the pulsing parameters on the skyrmion motion, shows low influence of the pulses rise-time and an external magnetic field. In addition the analysis after the irradiation shows that it influences notably the dynamics of skyrmions. In the irradiated zone the speed and angle of motion of these magnetic textures are strongly reduced. [ABSTRACT FROM AUTHOR]

• Single domain Co\Ni nano-magnets. • Shaping SFDs via local ion irradiation. • Nanosecond clocking of Co\Ni nano-magnets. • Time-dependence of coercivity. • Ga + ion dose dependent Coercive fields of single-domain Co\Ni nano-disks. Cobalt\Nickel multilayers with low perpendicular magnetic anisotropy are optimized for the lowest achievable coercivity while retaining the highest possible total magnetic moment, still supporting single-domain states. This optimization is done to achieve a vital clock-field reduction in nanomagnetic logic devices with perpendicular magnetic anisotropy, enabling highly efficient on-chip field clocking. It is shown that sub 10 mT coercivities are achievable utilizing a Ta 2 \Pt 1.5 [Co 0.2 \Ni 0.4 x8 stack in combination with precise manipulation of the anisotropy landscape via highly localized Ga + ion irradiation, in order to control the point of domain-wall nucleation. Statistical data is used to assess the Ga + ion dose-dependent coercivity and provide a detailed insight into the overall switching-field-distributions. Nanosecond field pulsing is used to assess the time-evolution of the nucleation fields, confirmed to be following the Arrhenius model at least down to pulse lengths of 10 ns, resulting in nucleation fields more than twice as high. The obtained findings are then applied to demonstrate the first pNML logic elements fulfilling the requirements for on-chip clocking schemes. [ABSTRACT FROM AUTHOR]

• Skyrmionic bubble like structures are artificially created. • Pt/Co/Ir and Pt/Co/W films are optimized for skyrmionic bubble like structures. • Focused ion beam irradiation is used to generate skyrmionic bubble like structures. • Focused ion beam irradiation locates and stabilizes the bubbles. • The created spin-textures show high stability and can be tuned in size. Skyrmions provide high potential for low power magnetic computing. However, we are lacking methods for the controlled nucleation of skyrmions in magnetic thin films. We present a procedure for a controlled generation of skyrmionic bubble like structures (SBSs) at well-defined spots by focused ion beam (FIB) irradiation of magnetic multilayers. Series of Pt/Co/Ir and Pt/Co/W multilayers with interfacial Dzyaloshinskii-Moriya interaction (iDMI) were sputtered and optimized with respect to the domain structure and development under magnetic field. Applying an external magnetic field pulse of specific strength to a sample in both the demagnetized domain state and the uniform ferromagnetic state results in the condensation and nucleation of bubbles, respectively. In multilayer films, SBSs form randomly across the sample. To control the bubble nucleation, we irradiate the multilayer stacks with 50 kV Ga + ions to alter the magnetic properties along a hexagonal grid. We observe nucleation and geometric confinement of bubbles within the center of the hexagons. The lowered anisotropy in irradiated regions forms potential barriers which stabilizes the bubbles at room temperature and zero field. FIB tuned magnetic thin films give an exciting platform to investigate the behavior of SBSs in a confined state and to study the possibilities of controlled field- and current-driven motion. [ABSTRACT FROM AUTHOR]