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Reducing the material sizes to the nanometer length scale leads to drastic modifications of the propagating lattice excitations (phonons) and their interactions with electrons and magnons.

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We report a systematic lattice dynamics study of EuSi_{2} films and nanoislands by in situ nuclear inelastic scattering on ^{151}Eu and ab initio theory. The Eu-partial phonon density of states of the nanoislands exhibits anomalous excess of phonon states at low and high energies, not present in the bulk and at the EuSi_{2}(001) surface. We demonstrate that atomic vibrations along the island-substrate interface give rise to phonon states both at low and high energies, while atomic vibrations across the island-island interface result in localized high-energy phonon modes.

This corrects the article DOI: 10.1103/PhysRevLett.116.185501.

A portable ultrahigh-vacuum system optimized for in situ variable-temperature X-ray scattering and spectroscopy experiments at synchrotron radiation beamlines was constructed and brought into operation at the synchrotron radiation facility ANKA of the Karlsruhe Institute of Technology, Germany. Here the main features of the new instrument are described and its capabilities demonstrated. The surface morphology, structure and stoichiometry of EuSi2 nano-islands are determined by in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy. A size reduction of about a factor of two of the nano-islands due to silicide decomposition and Eu desorption is observed after sample annealing at 1270 K for 30 min.

The thermal stability of parallel, high aspect ratio DySi 2 nanowires and nanoislands self-organized on vicinal Si(001) is investigated as a function of the annealing temperature from room temperature up to 760°C by in situ grazing incidence small-angle X-ray scattering (GISAXS). A transformation of the nanoobjects has been observed above a temperature of 500°C. The nanowires collapse forming small islands, while the nanoislands grow in size due to Ostwald ripening. The formation of facets is observed during annealing. A comprehensive understanding of the surface morphology changes is obtained by complementing the in situ GISAXS experiment with atomic force microscopy measurements.

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