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Magnetic skyrmions are topologically protected spin textures with promising prospects for applications in data storage. They can form a lattice state due to competing magnetic interactions and are commonly found in a small region of the temperature—magnetic field phase diagram. Recent work has demonstrated that these magnetic quasi-particles fluctuate at the μeV energy scale. Here, we use a coherent x-ray correlation method at an x-ray free-electron laser to investigate these fluctuations in a magnetic phase coexistence region near a first-order transition boundary where fluctuations are not expected to play a major role. Surprisingly, we find that the relaxation of the intermediate scattering function at this transition differs significantly compared to that deep in the skyrmion lattice phase. The observation of a compressed exponential behavior suggests solid-like dynamics, often associated with jamming. We assign this behavior to disorder and the phase coexistence observed in a narrow field-window near the transition, which can cause fluctuations that lead to glassy behavior. [ABSTRACT FROM AUTHOR]

We have searched for a signature of nonlocal magnetization dynamics or magnetization dynamics driven by pure spin currents, in magnetically soft polycrystalline Ni81Fe19/Cu/Co93Zr7 trilayers using ferromagnetic resonance. An interface-related enhancement of damping is expected for each ferromagnetic layer when incorporated in a trilayer; the enhancement should be absent where layer resonances overlap. While size effects in Gilbert damping have been identified, we note that expectations specific to spin pumping are not confirmed. [ABSTRACT FROM AUTHOR]

We have investigated the microwave properties of monodisperse, superparamagnetic γ-Fe2O3 nanoparticle arrays using broadband ferromagnetic resonance. We identify a novel field for resonance relationship in the films. Compared with ferromagnetic films of equal magnetization, resonance frequencies are suppressed for in-plane magnetization and enhanced for out-of-plane magnetization, over the range of 0–8 Ghz. The behavior identified is that of a superparamagnetic thin film, where thin-film dipolar fields act on a gradually saturating magnetization described by the Langevin function. Resonance linewidths can be described by the natural thermal dispersion in properties of the system. [ABSTRACT FROM AUTHOR]

We use X-ray Excited Luminescence Microscopy to investigate the elemental and layer resolved magnetic reversal in an interlayer exchange coupled (IEC) epitaxial Fe/Cr wedge/Co heterostructure. The transition from strongly coupled parallel Co-Fe reversal for Cr thickness tCr<0.34 nm to weakly coupled layer independent reversal for tCr>1.5 nm is punctuated at 0.34

We present a compact sample holder equipped with electromagnets and high frequency transmission lines; the sample holder is intended for combined x-ray magnetic circular dichroism (XMCD) and ferromagnetic resonance measurements (FMR). Time-resolved measurements of resonant x-ray detected FMR during forced precession are enabled by use of a rf excitation that is phase-locked to the storage ring bunch clock. Several applications of the combined XMCD+FMR technique are presented, demonstrating the flexibility of the experimental design. [ABSTRACT FROM AUTHOR]

We demonstrate the potential of x-ray excited luminescence microscopy for full-field elemental and magnetic sensitive imaging using a commercially available optical microscope, mounted on preexisting synchrotron radiation (SR) beamline end stations. The principal components of the instrument will be described. Bench top measurements indicate that a resolution of 1 μm or better is possible; this value was degraded in practice due to vibrations and/or drift in the end station and associated manipulator. X-ray energy dependent measurements performed on model solar cell materials and lithographically patterned magnetic thin film structures reveal clear elemental and magnetic signatures. The merits of the apparatus will be discussed in terms of conventional SR imaging techniques. [ABSTRACT FROM AUTHOR]