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Université de Fribourg

${\eta}$-paired superconducting hidden phase in photodoped Mott insulators

Li, Jiajun ; Golez, Denis ; Werner, Philipp ; Eckstein, Martin

In: Physical Review B, 2020, vol. 102, no. 16, p. 165136

We show that a metastable η-pairing superconducting phase can be induced by photodoping doublons and holes into a strongly repulsive fermionic Hubbard model. The doublon-hole condensate originates from an intrinsic doublon-hole exchange interaction and does not rely on the symmetry of the half-filled Hubbard model. It extends over a wide range of doublon densities and effective temperatures....

Université de Fribourg

NESSi : The Non-Equilibrium Systems Simulation package

Schüler, Michael ; Golež, Denis ; Murakami, Yuta ; Bittner, Nikolaj ; Herrmann, Andreas ; U.R.Strand, Hugo ; Werner, Philipp ; Eckstein, Martin

In: Computer Physics Communications, 2020, vol. 257, no. 2020, p. 107484

The nonequilibrium dynamics of correlated many-particle systems is of interest in connection with pump–probe experiments on molecular systems and solids, as well as theoretical investigations of transport properties and relaxation processes. Nonequilibrium Green’s functions are a powerful tool to study interaction effects in quantum many-particle systems out of equilibrium, and to extract...

Université de Fribourg

Entropy and electronic orders of the three-orbital Hubbard model with antiferromagnetic Hund coupling

Yue, Changming ; Hoshino, Shintaro ; Werner, Philipp

In: Physical Review B, 2020, vol. 102, no. 19, p. 195103

An antiferromagnetic Hund coupling in multiorbital Hubbard systems induces orbital freezing and an associated superconducting instability, as well as unique composite orders in the case of an odd number of orbitals. While the rich phase diagram of the half-filled three-orbital model has recently been explored in detail, the properties of the doped system remain to be clarified. Here, we...

Université de Fribourg

Dynamical conductivity of lithium-intercalated hexagonal boron nitride films : A memory function approach

Rukelj, Zoran

In: Physical Review B, 2020, vol. 102, no. 20, p. 205108

This work is a study of dynamical conductivity of a quasi-two-dimensional heterostructure Li(BN)8. The conducting electrons have a free-electron-like parabolic dispersion and are assumed to scatter only on acoustic phonons. The approach used to derive the generalized Drude relation with frequency and temperature dependent relaxation consists of defining the induced current density as a...

Université de Fribourg

Nature of native atomic defects in ${\mathrm{ZrTe}}_{5}$ and their impact on the low-energy electronic structure

Salzmann, Björn ; Pulkkinen, Aki ; Hildebrand, Baptiste ; Jaouen, Thomas ; Zhang, S. N. ; Martino, E. ; Li, Q. ; Gu, G. ; Berger, Helmuth ; Yazyev, O. V. ; Akrap, Ana ; Monney, Claude

In: Physical Review Materials, 2020, vol. 4, no. 11, p. 114201

Over the past decades, investigations of the anomalous low-energy electronic properties of ZrTe5 have reached a wide array of conclusions. An open question is the growth method's impact on the stoichiometry of ZrTe5 samples, especially given the very small density of states near its chemical potential. Here we report on high- resolution scanning tunneling microscopy and spectroscopy...

Université de Fribourg

Misfit layer compounds: a platform for heavily doped 2D transition metal dichalcogenides

Leriche, Raphaël T. ; Palacio‐Morales, Alexandra ; Campetella, Marco ; Tresca, Cesare ; Sasaki, Shunsuke ; Brun, Christophe ; Debontridder, François ; David, Pascal ; Arfaoui, Imad ; Šofranko, Ondrej ; Samuely, Tomas ; Kremer, Geoffroy ; Monney, Claude ; Jaouen, Thomas ; Cario, Laurent ; Calandra, Matteo ; Cren, Tristan

In: Advanced Functional Materials, 2020, p. 2007706

Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double‐layer field‐effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈1 × 1014 cm−2, while a somewhat larger...

Université de Fribourg

Mean-field theory of inhomogeneous fluids

Tschopp, Salomée M. ; Vuijk, Hidde Derk ; Sharma, Abhinav ; Brader, Joseph M.

In: Physical Review E, 2020, vol. 102, no. 4, p. 042140

The Barker-Henderson perturbation theory is a bedrock of liquid-state physics, providing quantitative predictions for the bulk thermodynamic properties of realistic model systems. However, this successful method has not been exploited for the study of inhomogeneous systems. We develop and implement a first-principles “Barker- Henderson density functional,” thus providing a robust and...

Université de Fribourg

Carbon‐assisted stable silver nanostructures

Abdollahi, S. Narjes ; Ochoa Martínez, Efraín ; Kilchoer, Cédric ; Kremer, Geoffroy ; Jaouen, Thomas ; Aebi, Philipp ; Hellmann, Tim ; Mayer, Thomas ; Gu, Yibei ; Wiesner, Ulrich B. ; Steiner, Ullrich ; Wilts, Bodo D. ; Gunkel, Ilja

In: Advanced Materials Interfaces, 2020, vol. 7, no. 23, p. 2001227

Nanostructured silver stands out among other plasmonic materials because its optical losses are the lowest of all metals. However, nanostructured silver rapidly degrades under ambient conditions, preventing its direct use in most plasmonic applications. Here, a facile and robust method for the preparation of highly stable nanostructured silver morphologies is introduced. 3D nanostructured...

Université de Fribourg

How circular dichroism in time- and angle-resolved photoemission can be used to spectroscopically detect transient topological states in graphene

Schüler, Michael ; Giovannini, Umberto De ; Hübener, Hannes ; Rubio, Angel ; Sentef, Michael A. ; Devereaux, Thomas P. ; Werner, Philipp

In: Physical Review X, 2020, vol. 10, no. 4, p. 041013

Pumping graphene with circularly polarized light is the archetype of light-tailoring topological bands. Realizing the induced Floquet-Chern-insulator state and demonstrating clear experimental evidence for its topological nature has been a challenge, and it has become clear that scattering effects play a crucial role. We tackle this gap between theory and experiment by employing microscopic...

Université de Fribourg

Transition from light diffusion to localization in three-dimensional amorphous dielectric networks near the band edge

Haberko, Jakub ; Froufe-Pérez, Luis S. ; Scheffold, Frank

In: Nature Communications, 2020, vol. 11, no. 1, p. 4867

AbstractLocalization of light is the photon analog of electron localization in disordered lattices, for whose discovery Anderson received the Nobel prize in 1977. The question about its existence in open three-dimensional materials has eluded an experimental and full theoretical verification for decades. Here we study numerically electromagnetic vector wave transmittance through realistic...