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This corrects the article DOI: 10.1103/PhysRevLett.116.185501.
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Comprehensive studies of lattice dynamics in the ferromagnetic semiconductor EuO have been performed by a combination of inelastic x-ray scattering, nuclear inelastic scattering, and ab initio calculations. A remarkably large broadening of the transverse acoustic phonons was discovered at temperatures above and below the Curie temperature T_{C}=69 K. This result indicates a surprisingly strong momentum-dependent spin-phonon coupling induced by the spin dynamics in EuO.
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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.
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The structural and magnetic properties of ultrathin FeO(111) films on Pt(111) with thicknesses from 1 to 16 monolayers (MLs) were studied using the nuclear inelastic scattering of synchrotron radiation. A distinct evolution of vibrational characteristics with thickness, revealed in the phonon density of states (PDOS), shows a textbook transition from 2D to 3D lattice dynamics. For the thinnest films of 1 and 2 ML, the low-energy part of the PDOS followed a linear âE dependence in energy that is characteristic for two-dimensional systems. This dependence gradually transforms with thickness to the bulk âE^{2} relationship. Density-functional theory phonon calculations perfectly reproduced the measured 1-ML PDOS within a simple model of a pseudomorphic FeO/Pt(111) interface. The calculations show that the 2D PDOS character is due to a weak coupling of the FeO film to the Pt(111) substrate. The evolution of the vibrational properties with an increasing thickness is closely related to a transient long-range magnetic order and stabilization of an unusual structural phase.
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The changes in crystal structure of LiFeSi(2)O(6) induced by the phase transition between the high-temperature C2/c and low-temperature P2(1)/c phase are studied using the density functional theory. For both monoclinic phases, the phonon dispersion curves and phonon density of states are calculated. The infrared absorption coefficients are obtained and analyzed in both structural phases of LiFeSi(2)O(6). The soft mode inducing the phase transition is revealed at the Z point of the Brillouin zone of the high-symmetry C2/c phase. The pressure dependence of the soft mode is studied and the mechanism of the structural phase transition in LiFeSi(2)O(6) is discussed.
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We compare the atomic dynamics of the glass to that of the relevant crystal. In the spectra of inelastic scattering, the boson peak of the glass appears higher than the transverse acoustic (TA) singularity of the crystal. However, the density of states shows that they have the same number of states. Increasing pressure causes the transformation of the boson peak of the glass towards the TA singularity of the crystal. Once corrected for the difference in the elastic medium, the boson peak matches the TA singularity in energy and height. This suggests the identical nature of the two features.
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Density functional theory was used to study structural and dynamical changes related to the magnetostructural phase transition in MnAs. The soft mode inducing the transition from the high-symmetry hexagonal to the low-symmetry orthorhombic phase was revealed. A giant coupling between the soft mode and magnetic moments was found and its crucial role in the magnetostructural transition was established. The estimated phonon contribution to the total entropy change has the opposite sign to the magnetic entropy change.
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Experimental and theoretical studies, of the Fe-partial phonon density of states (PDOS) for Fe52.5Cr47.5 alloy having alpha and sigma phases were carried out. The former using the nuclear resonant inelastic x-ray scattering method, and the latter with the direct one. Characteristic features of PDOS, which distinguish one phase from the other, were revealed and successfully reproduced by the theory. Data pertinent to the dynamics such as the Lamb-Mössbauer factor, f, the kinetic energy per atom, E(k), and the mean force constant, D, were directly derived, while vibrational specific heat at constant volume, C(V), and vibrational entropy, S were calculated using the Fe partial PDOS. Based on the values of f and C(V), we determined Debye temperatures, Theta(D). An excellent agreement for some quantities derived from experiment and first-principles theory, like C(V) and quite good ones for others like D and S were obtained.
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The structure and stability properties of wadsleyite II as the new phase of Mg(2)SiO(4) has been studied at high pressure by the DFT method. The pressure range corresponds to the transition zone in the Earth. At zero pressure the calculated lattice parameters of the wadsleyite II structure are a=5.749 Å, b=28.791 Å and c=8.289 Å with the density ρ=3406 kg m(-3). The third order Birch-Murnaghan equation of state has been determined for the structure with isothermal bulk moduli K(T)=160.1 GPa and K(T)'=4.3 at a pressure range up to 50 GPa. The elasticity tensor coefficients C(ij)(P), as well as the compressional and shear wave velocities and their pressure derivatives, have been calculated using the deformation method at a range of pressures up to 25 GPa. The results agree with the experimental data and structure properties of the wadsleyite II model. The properties of the wadsleyite II phase are very close to the wadsleyite phase.
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A polycrystalline sample of Tb(3)Cu(4)Si(4) was investigated by means of magnetometric, electrical resistivity, thermopower and heat capacity measurements. This paper also includes reanalyses of former neutron diffraction data. The compound crystallizes in a Gd(3)Cu(4)Ge(4)-type orthorhombic structure (Immm space group), in which the Tb ions occupy two inequivalent sites (2d and 4e). The bulk results indicate that these two magnetic sublattices order antiferromagnetically at different temperatures, in agreement with the neutron diffraction data.
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The phonon dispersion curves of the superconductor PuCoGa(5) were studied by inelastic x-ray scattering at room temperature. The experimental data agree well with ab initio lattice dynamics calculations. An accurate description of the phonon spectrum is obtained only when a local Coulomb repulsion U approximately equal 3 eV among 5f electrons is taken into account.
