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The article offers information on a study conducted by the authors on transfer of angular momentum in optical near-fields of optical antennas. Topics discussed include deviation of geometrical antenna from photoemission yield, confinement of near-field to antenna arms with reduced polarization, increased circular polarization in the center of antenna, and momentum transfer by transfer of spin polarized electrons.

Using a combination of photoemission electron microscopy and numerical simulations, we investigated the angular moment transfer in strongly enhanced optical near-fields of artificially fabricated optical antennas. The polarization dependence of the optical near-field enhancement has been measured in a maximum symmetric geometry, i.e., excitation by a normal incident planar wave. Finite-difference time-domain simulations for the realistic antenna geometries as determined by high-resolution electron microscopy reveal a very good agreement with experimental data. The agreement confirms that the geometrical asymmetries and inhomogeneities due to the nanoscale fabrication process preserve the circular polarization in the gap regions with strong near-field enhancement. [ABSTRACT FROM AUTHOR]

We investigate the phase separation of the solid solution CoTi(1− x )Mn x Sb into the two Heusler compounds CoTiSb and CoMnSb. Energy-dispersive X-ray spectroscopy measurements on the two-phase material reveal the presence of size- and shape-tunable CoTiSb regions in a CoMnSb matrix. We demonstrate that the formed phase and grain boundaries have a considerable influence on the phonon scattering processes, which leads to a reduction in the thermal conductivity by a factor of three compared to single-phase CoTiSb. [ABSTRACT FROM AUTHOR]

Detecting and identifying drones is of great interest due to the proliferation of highly manoeuverable drones with on-board sensors of increasing sensing capabilities. In this paper, we investigate the use of radars for tackling this problem. In particular, we focus on the problem of detecting rotary drones and distinguishing between single-propeller and multi-propeller drones using a micro-Doppler analysis. Two different radars were used, an ultra wideband (UWB) continuous wave (CW) C-band radar and an automotive frequency modulated continuous wave (FMCW) W-band radar, to collect micro-Doppler signatures of the drones. By taking a closer look at HElicopter Rotor Modulation (HERM) lines, the spool and chopping lines are identified for the first time in the context of drones to determine the number of propeller blades. Furthermore, a new multi-frequency analysis method using HERM lines is developed, which allows the detection of propeller rotation rates (spool and chopping frequencies) of single and multi-propeller drones. Therefore, the presented method is a promising technique to aid in the classification of drones. [ABSTRACT FROM AUTHOR]

A series of Al and MgO-capped Co2FeAl0.5Si0.5 epitaxial thin films grown on MgO with various levels of L21 ordering was obtained by in situ annealing. The films were studied by means of x-ray absorption spectroscopy, x-ray magnetic circular dichroism (XMCD), magneto-optical Kerr effect magnetometry, and Brillouin light scattering. We find the anisotropy constants decrease, while the spin wave stiffness increases as the samples are annealed to higher temperatures. The magnetization as determined by Brillouin light scattering reveals a maximum value at intermediate annealing temperatures. Surprisingly, the orbital-to-spin-moment ratio (as seen from XMCD) is essentially stable through the sample series and does not change upon annealing, despite the observed changes in anisotropy and exchange. [ABSTRACT FROM AUTHOR]

The interface and bulk magnetic properties of epitaxial thin films of the Heusler compounds Co2Cr0.6Fe0.4Al/Mg/AlOx and CoCr2Al/Mg/AlOx are investigated. We compare the magnetization measured by x-ray magnetic circular dichroism experiments in surface sensitive total electron yield mode (information depth of 2–3 nm) and in bulk sensitive transmission mode. The pronounced temperature dependence of the magnetoresistance of tunneling junctions with Heusler electrodes, which is often related to weakened interface magnetism, is discussed. Evidence is given that this explanation does not apply to the compounds investigated here. [ABSTRACT FROM AUTHOR]