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Electronic Structure and Properties of Superconducting Materials with Simple Fermi Surfaces

Jarlborg, T.

In: Journal of Superconductivity and Novel Magnetism, 2015, vol. 28, no. 4, p. 1231-1236

Université de Fribourg

Unveiling the Semimetallic Nature of 1$T$-TiSe$_2$ by Doping its Charge Density Wave

Jaouen, Thomas ; Rumo, Maxime ; Hildebrand, Baptiste ; Mottas, Marie-Laure ; Nicholson, Christopher W. ; Kremer, Geoffroy ; Salzmann, Björn ; Vanini, Fabiano ; Barreteau, C. ; Giannini, E. ; Beck, Hans-Peter ; Aebi, Philipp ; Monney, Claude

The semimetallic or semiconducting nature of the transition metal dichalcogenide 1$T$-TiSe$_2$ remains under debate after many decades mainly due to the fluctuating nature of its 2 x 2 x 2 charge-density-wave (CDW) phase at room- temperature. In this letter, using angle-resolved photoemission spectroscopy, we unambiguously demonstrate that the 1$T$-TiSe$_2$ normal state is semimetallic with ...

Université de Fribourg

Formation and Reactivity of [(tacn)-N-CO-Re(III)Br(CO)(2)](+) in Water : a Theoretical and Experimental Study

Zobi, Fabio ; Blacque, Olivier ; Steyl, Gideon ; Spingler, Bernhard ; Alberto, Roger

In: Inorganic Chemistry, 2009, vol. 48, no. 11, p. 4963-4970

The chemistry of [(tacn)-N-CO-Re(III)(CO)(2)Br]X (X = Cl or Br), obtained in good yield from the reaction of fac-[(tacn)Re(I)(CO)(3)]Br (1, tacn = 1,4,7- triazacyclononane) with X(2) in water, is described. The [(tacn)-N-CO-Re(III)(CO) (2)Br]X complex (2 with X = Br(-); 2a with X = BrCl(2)(-)), which we have previously communicated, is characterized by an unusual three-membered ring acyl amide...

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

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

Monolithic resorcinol–formaldehyde alcogels and their corresponding nitrogen-doped activated carbons

Civioc, Romain ; Lattuada, Marco ; Koebel, Matthias M. ; Galmarini, Sandra

In: Journal of Sol-Gel Science and Technology, 2020, vol. 95, no. 3, p. 719–732

Here we report the adaptation of formaldehyde crosslinked phenolic resin-based aerogel and xerogel synthesis to ethanol-based solvent systems. Three specific formulations, namely one resorcinol–formaldehyde (RF) and two resorcinol– melamine–formaldehyde (RMF) systems were studied. As-prepared resins were characterized in terms of envelope and skeletal density. Furthermore, resin samples ...

Université de Fribourg

Ab initio description of the ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+{\delta}}$ electronic structure

Nokelainen, Johannes ; Lane, Christopher ; Markiewicz, Robert S. ; Barbiellini, Bernardo ; Pulkkinen, Aki ; Singh, Bahadur ; Sun, Jianwei ; Pussi, Katariina ; Bansil, Arun

In: Physical Review B, 2020, vol. 101, no. 21, p. 214523

Bi-based cuprate superconductors are important materials for both fundamental research and applications. As in other cuprates, the superconducting phase in the Bi compounds lies close to an antiferromagnetic phase. Our density functional theory calculations based on the strongly-constrained-and- appropriately-normed exchange correlation functional in ...

Université de Fribourg

Superconductivity-induced transverse plasma mode and phonon anomaly in the $c$-axis response of the bilayer compound ${\mathrm{RbCa}}_{2}{\mathrm{Fe}}_{4}{\mathrm{As}}_{4}{\mathrm{F}}_{2}$

Xu, Bing ; Munzar, Dominik ; Dubroka, Adam ; Sheveleva, Evgeniia ; Lyzwa, Fryderyk ; Maršík, Premysl ; Wang, C. N. ; Wang, Z. C. ; Cao, G. H. ; Bernhard, Christian

In: Physical Review B, 2020, vol. 101, no. 21, p. 214512

We studied the infrared response of polycrystalline samples of the iron arsenide superconductor (Rb,Cs)Ca2Fe4As4F2 (Rb,Cs-12442), which has a bilayer structure similar to the high-Tc cuprates YBa2Cu3O7 (YBCO) and Bi2Sr2CaCu2O8. The c-axis reflectivity spectra Rc have been derived from the reflectivity spectra of the polycrystalline samples Rpoly and the in-plane spectrum of a corresponding...

Université de Fribourg

Magneto-transport in La2/3Sr1/3MnO3/YBa2Cu3O7/Alq3/Co spin-valves

Cerreta, Andrea ; Gaina, Roxana ; Nuccio, Laura ; Marozau, Ivan ; Sen, Kaushik ; De Andrés Prada, Roberto ; Sarkar, Subhrangsu ; Bernhard, Christian

In: EPL (Europhysics Letters), 2020, vol. 129, no. 3, p. 37002

We studied how an additional layer of the high superconductor YBCO affects the magneto-transport across a LSMO/Alq3/Co spin-valve structure. We found that up to a thickness of at least 10 nm the YBCO layer on top of LSMO hardly changes the spin-valve effect, since the device resistance still depends on the relative orientation of the LSMO and Co magnetization. The spin-valve effect persists...