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Optical and structural study of the pressure-induced phase transition of CdWO 4
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First-principles studies of the local structure and relaxor behavior of Pb ( Mg 1 / 3 Nb 2 / 3 ) O 3 – PbTiO 3 -derived ferroelectric perovskite solid solutions
We have investigated the effect of transition-metal dopants on the local structure of the prototypical 0.75Pb(Mg 1/3 Nb 2/3 )O 3 –0.25PbTiO 3 relaxor ferroelectric. We find that these dopants give rise to very different local structure and other physical properties. For example, when Mg is partially substituted by Cu or Zn, the displacement of Cu or Zn is much larger than that of Mg and is even comparable to that of Nb. The polarization of these systems is also increased, especially for the Cu-doped solution, due to the large polarizability of Cu and Zn. As a result, the predicted maximum dielectric constant temperatures T m are increased. On the other hand, the replacement of a Ti atom with a Mo or Tc atom dramatically decreases the displacements of the cations and the polarization, and thus, the T m values are also substantially decreased. Here, the higher T m cannot be explained by the conventional argument based on the ionic radii of the cations. Furthermore, we find that Cu, Mo, or Tc doping increases the cation displacement disorder. Here, the effect of the dopants on the temperature dispersion ΔT m , which is the change in T m for different frequencies, is also discussed. Our findings lay the foundation for further investigations of unexplored dopants.
Rotationally invariant slave-boson and density matrix embedding theory: Unified framework and comparative study on the one-dimensional and two-dimensional Hubbard model [Rotationally invariant slave-boson and density matrix embedding theory: A unified framework and a comparative study on the 1D and 2D Hubbard Model]
We present detailed benchmark ground-state calculations of the one- and two-dimensional Hubbard model utilizing the cluster extensions of the rotationally invariant slave-boson mean-field theory and the density matrix embedding theory. Our analysis shows that the overall accuracy and the performance of these two methods are very similar. Furthermore, we propose a unified computational framework that allows us to implement both of these techniques on the same footing. In conclusion, this provides us with a different line of interpretation and paves the ways for developing systematically distinct generalizations of these complementary approaches.
Disentangling transient charge order from structural dynamics contributions during coherent atomic motion studied by ultrafast resonant x-ray diffraction [Disentangling charge and structural contributions during coherent atomic motions studied by ultrafast resonant x-ray diffraction]
We report on the ultrafast dynamics of charge order and structural response during the photoinduced suppression of charge and orbital order in a mixed-valence manganite. Employing femtosecond time-resolved resonant x-ray diffraction below and at the Mn K absorption edge, we present a method to disentangle the transient charge order and structural dynamics in thin films of Pr 0.5 Ca 0.5 MnO 3 . Based on the static resonant scattering spectra, we extract the dispersion correction of charge-ordered Mn 3+ and Mn 4+ ions, allowing us to separate the transient contributions of purely charge order from structural contributions to the scattering amplitude after optical excitation. Furthermore, our finding of a coherent structural mode at around 2.3THz, which primarily modulates the lattice but does not strongly affect the charge order, supports the picture of the charge order being the driving force of the combined charge, orbital, and structural transition.
Detailed study of the nuclear dependence of the EMC effect and short-range correlations
Not Available
Method for studying the rapidity fluctuation and de-correlation of harmonic flow in heavy-ion collisions
Not Available