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Université de Fribourg

Spontaneously orbital-selective superconductivity in a three-orbital Hubbard model

Ishigaki, Kosuke ; Nasu, Joji ; Koga, Akihisa ; Hoshino, Shintaro ; Werner, Philipp

In: Physical Review B, 2018, vol. 98, no. 23, p. 235120

We study a three-orbital Hubbard model with negative Hund's coupling in infinite dimensions, combining dynamical mean-field theory with continuous time quantum Monte Carlo simulations. This model, which is relevant for the description of alkali- doped fullerides, has previously been shown to exhibit a spontaneous orbital-selective Mott phase in the vicinity of the superconducting phase....

Université de Fribourg

Beyond the molecular movie: Dynamics of bands and bonds during a photoinduced phase transition

Nicholson, Christopher W. ; Lücke, A. ; Schmidt, W. G. ; Puppin, M. ; Rettig, L. ; Ernstorfer, R. ; Wolf, M.

In: Science, 2018, vol. 362, no. 6416, p. 821–825

Ultrafast nonequilibrium dynamics offer a route to study the microscopic interactions that govern macroscopic behavior. In particular, photoinduced phase transitions (PIPTs) in solids provide a test case for how forces, and the resulting atomic motion along a reaction coordinate, originate from a nonequilibrium population of excited electronic states. Using femtosecond photoemission, we...

Université de Fribourg

Quantum Boltzmann equation for strongly correlated systems: Comparison to dynamical mean field theory

Wais, Michael ; Eckstein, Martin ; Fischer, R. ; Werner, Philipp ; Battiato, M. ; Held, K.

In: Physical Review B, 2018, vol. 98, no. 13, p. 134312

We investigate the potential of a quantum Boltzmann equation without momentum conservation for description of strongly correlated electron systems out of equilibrium. In a spirit similar to dynamical mean field theory (DMFT), the momentum conservation of the electron-electron scattering is neglected, which yields a time-dependent occupation function for the equilibrium spectral function, even...

Université de Fribourg

Circularly polarized reflection from the scarab beetle Chalcothea smaragdina: light scattering by a dual photonic structure

McDonald, Luke T. ; Finlayson, Ewan D. ; Wilts, Bodo D. ; Vukusic, Pete

In: Interface Focus, 2017, vol. 7, no. 4, p. 20160129

Helicoidal architectures comprising various polysaccharides, such as chitin and cellulose, have been reported in biological systems. In some cases, these architectures exhibit stunning optical properties analogous to ordered cholesteric liquid crystal phases. In this work, we characterize the circularly polarized reflectance and optical scattering from the cuticle of the beetle Chalcothea...

Consortium of Swiss Academic Libraries

PAD: A New Interactive Knowledge-Based Analog Design Approach

Stefanovic, Danica ; Kayal, Maher ; Pastre, Marc

In: Analog Integrated Circuits and Signal Processing, 2005, vol. 42, no. 3, p. 291-299