Université de Fribourg

First-principles studies of spin-orbital physics in pyrochlore oxides

Shinaoka, Hiroshi ; Motome, Yukitoshi ; Miyake, Takashi ; Ishibashi, Shoji ; Werner, Philipp

In: Journal of Physics: Condensed Matter, 2019, vol. 31, no. 32, p. 323001

The pyrochlore oxides A2B2O7 exhibit a complex interplay between geometrical frustration, electronic correlations, and spin–orbit coupling (SOC), due to the lattice structure and active charge, spin, and orbital degrees of freedom. Understanding the properties of these materials is a theoretical challenge, because their intricate nature depends on material-specific details and quantum...

Université de Fribourg

Linear behavior of the optical conductivity and incoherent charge transport in ${\mathrm{BaCoS}}_{2}$

Santos-Cottin, D. ; Klein, Y. ; Werner, Philipp ; Miyake, Takashi ; Medici, L. de ; Gauzzi, A. ; Lobo, R. P. S. M. ; Casula, Michele

In: Physical Review Materials, 2018, vol. 2, no. 10, p. 105001

Optical conductivity measurements on a BaCoS2 single crystal unveil an unusual linear behavior over a broad spectral range. In the paramagnetic phase above 300 K, the spectrum shows no gap, which contradicts the previously proposed scenario of a charge-transfer Mott insulator. Ab initio dynamical mean field theory calculations including a retarded Hubbard interaction explain the data in terms...