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Université de Fribourg

The rise of angiosperms pushed conifers to decline during global cooling

Condamine, Fabien L. ; Silvestro, Daniele ; Koppelhus, Eva B. ; Antonelli, Alexandre

In: Proceedings of the National Academy of Sciences, 2020, vol. 117, no. 46, p. 28867–28875

Competition among species and entire clades can impact species diversification and extinction, which can shape macroevolutionary patterns. The fossil record shows successive biotic turnovers such that a dominant group is replaced by another. One striking example involves the decline of gymnosperms and the rapid diversification and ecological dominance of angiosperms in the Cretaceous. It is...

Université de Fribourg

Entropy and specific heat of the infinite-dimensional three-orbital Hubbard model

Yue, Changming ; Werner, Philipp

In: Physical Review B, 2020, vol. 102, no. 8, p. 085102

The Hund's coupling in multiorbital Hubbard systems induces spin freezing and associated Hund metal behavior. Using dynamical mean-field theory, we explore the effect of local moment formation, spin, and charge excitations on the entropy and specific heat of the three-orbital model. For fillings 2≲n<3 and low temperature, we demonstrate a substantial enhancement of the entropy in the...

Université de Fribourg

Light-induced evaporative cooling of holes in the Hubbard model

Werner, Philipp ; Eckstein, Martin ; Müller, Markus ; Refael, Gil

In: Nature Communications, 2019, vol. 10, no. 1, p. 5556

An elusive goal in the field of driven quantum matter is the induction of long-range order. Here, we propose a mechanism based on light-induced evaporative cooling of holes in a correlated fermionic system. Since the entropy of a filled narrow band grows rapidly with hole doping, the isentropic transfer of holes from a doped Mott insulator to such a band results in a drop of temperature....

Université de Fribourg

Entropy-cooled nonequilibrium states of the Hubbard model

Werner, Philipp ; Li, Jianju ; Golež, Denis ; Eckstein, Martin

In: Physical Review B, 2019, vol. 100, no. 15, p. 155130

We show that the recently proposed cooling-by-doping mechanism allows one to efficiently prepare interesting nonequilibrium states of the Hubbard model. Using nonequilibrium dynamical mean field theory and a particle-hole symmetric setup with dipolar excitations to full and empty bands we produce cold photodoped Mott insulating states with a sharp Drude peak in the optical conductivity, a ...

Consortium of Swiss Academic Libraries

Nonthermal particles and photons in starburst regions and superbubbles

Bykov, Andrei

In: The Astronomy and Astrophysics Review, 2014, vol. 22, no. 1, p. 1-54

Consortium of Swiss Academic Libraries

X-ray spectroscopy of stars

Güdel, Manuel ; Nazé, Yaël

In: The Astronomy and Astrophysics Review, 2009, vol. 17, no. 3, p. 309-408

Consortium of Swiss Academic Libraries

Properties of cosmological filaments extracted from Eulerian simulations

Gheller, C. ; Vazza, F. ; Favre, J. ; Brüggen, M.

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 453, no. 2, p. 1164-1185