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A periodic arrangement of chains of gold disks shows pronounced plasmonic grating resonances. These have a clear impact on the surface enhanced Raman-scattering (SERS) signal from 4-methylbenzenethiol molecules, which form self-assembled monolayers on the gold surface: Besides a clear polarization dependence, the SERS-spectra also exhibit a maximum when the excitation laser wavelength matches the plasmonic grating resonance. These features are explained by a combined near and far field coupling of the individual plasmonic dipoles allowing the design of optimized nanostructures for effective SERS substrates in the future. [ABSTRACT FROM AUTHOR]

(0001) GaN single crystals having a thickness of 3.4 mm and a density of in-grown dislocations of 3.5 x 106 cm-2 have been deformed at room temperature using a cube corner, a Berkovich and a Vickers indenter, respectively. Cube corner indentations were performed in a scanning electron microscope in order to observe the deformation in situ. Subsequently, cracks and dislocations at the indentations were investigated by means of optical microscopy, scanning electron microscopy in secondary electron contrast and cathodoluminescence imaging. The arrangement of dislocations is determined by the symmetry of the indented surface. In contrast, the formation of cracks depends on both the shape and the orientation of the indenter. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Structural modulations hosted by complex oxides are-beyond relative orientation changes of 'rigid units'-accompanied by characteristic distortions of coordination polyhedra. Electronic structure calculations in the local density approximation, performed at model clusters derived from positionally modulated structures, proved that the molecular-orbital structure also sensitively reflects such distortions. The latter crystal-field splitting of unoccupied states is accessible by high-resolution electron energy-loss near-edge structure (ELNES) spectroscopy. However, since ELNES spectra average over many different individual target-ion environments, the resulting ELNES possesses significantly broadened spectral features. In this contribution, such broadening is shown to dramatically influence the spectral shape of the Ti-L2,3 ELNES acquired at the strongly modulated fresnoite framework compound Sr2TiSi2O8. [ABSTRACT FROM AUTHOR]

We have performed a two-step liquid phase epitaxy yielding ensembles of SiGe/Si(001) dot molecules with a specific and unique number of dots. An undersaturation of the initial bismuth solution causes strain-induced pits in the epitaxial Si0.985Ge0.015 layer which are effectively preserved during subsequent Si0.68Ge0.32 dot growth at considerably lower temperatures. Since the latter process happens extremely close to thermodynamic equilibrium, we are able to interrupt it after the formation of ensembles of dimers, trimers or quadruplets, respectively. The crosslike ensemble symmetry is discussed in terms of strain energy distribution as revealed by finite element calculations. [ABSTRACT FROM AUTHOR]

We demonstrate spin pumping and inverse spin Hall effect (ISHE) in an all oxide heterostructure composed of two oxides with different respective crystal structures. Y3 Fe5 O12 (YIG) is used as a spin source, being a perfect candidate because of its low damping and insulating behavior. SrRuO3 (SRO), a perovskite oxide with metallic conductivity, serves as a spin sink. Spin pumping is shown by the increase of the damping in ferromagnetic resonance for the YIG in the presence of an SRO top layer and by the inverse spin Hall effect appearing in the SRO. Transmission electron microscopy shows that the growth of YIG is fully epitaxial, while the SRO grows in islands of several polycrystaline phases, a fact which strongly influences the measured ISHE. The magnetization of the YIG remains unaffected by the SRO layer while the SRO no longer shows the low temperature ferromagnetism typically observed in monocrystalline layers. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the infrared photoluminescence emission from Ge(Si) quantum dots coupled with collective Mie modes of silicon nanopillars. We show that the excitation of band edge dipolar modes of a linear nanopillar array results in strong reshaping of the photoluminescence spectra. Among other collective modes, the magnetic dipolar mode with the polarization along the array axis contributes the most to the emission spectrum, exhibiting an experimentally measured Q -factor of around 500 for an array of 11 pillars. The results belong to the first experimental evidence of light emission enhancement of quantum emitters applying collective Mie resonances in finite nanoresonators and therefore represent an important contribution to the new field of active all-dielectric meta-optics., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Transition-metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co-P films were deposited by using PH 3 plasma as the phosphorus source and an extra H 2 plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self-limited layer-by-layer growth, and the deposited Co-P films were highly pure and smooth. The Co-P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co-P films prepared by the traditional post-phosphorization method. Moreover, the deposition of ultrathin Co-P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three-dimensional (3D) architectures., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

Resonant dielectric nanostructures represent a promising platform for light manipulation at the nanoscale. In this paper, we describe an active photonic system based on Ge(Si) quantum dots coupled to silicon nanodisks. We show that Mie resonances govern the enhancement of the photoluminescent signal from embedded quantum dots due to a good spatial overlap of the emitter position with the electric field of Mie modes. We identify the coupling mechanism, which allows for engineering the resonant Mie modes through the interaction of several nanodisks. In particular, the mode hybridization in a nanodisk trimer results in an up to 10-fold enhancement of the luminescent signal due to the excitation of resonant antisymmetric magnetic and electric dipole modes.