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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

Long-ranged Cu-based order with $$d_{z^2}$$ orbital character at a YBa2Cu3O7/ manganite interface

Gaina, Roxana ; Nicholson, Christopher W. ; Rumo, Maxime ; Sarkar, Subhrangsu ; Khmaladze, Jarji ; Paris, Eugenio ; Tseng, Yi ; Zhang, Wenliang ; Asmara, Teguh C. ; McNally, Daniel ; Piamonteze, Cinthia ; Weschke, Eugen ; Schmitt, Thorsten ; Monney, Claude ; Bernhard, Christian

In: npj Quantum Materials, 2021, vol. 6, no. 1, p. 12

The interplay of nearly degenerate orders in quantum materials can lead to a myriad of emergent phases. A prominent case is that of the high-Tc cuprates for which the relationship between superconductivity and a short-ranged, incommensurate charge density wave in the CuO2 planes involving the dx2−y2 orbitals (Cu-CDW) is a subject of great current interest. Strong modifications of the...

Université de Fribourg

Muon spin rotation and infrared spectroscopy study of Ba$_{1-x}$Na$_{x}$Fe$_{2}$As$_{2}$

Sheveleva, Evgeniia ; Xu, Bing ; Marsik, Premysl ; Lyzwa, Fryderyk ; Mallett, Benjamin P. P. ; Willa, K. ; Meingast, C. ; Wolf, Th. ; Shevtsova, T. ; Pashkevich, Yu. G. ; Bernhard, Christian

In: Physical Review B, 2020, vol. 101, no. 22, p. 224515

The magnetic and superconducting properties of a series of underdoped Ba 1 − x Na x Fe 2 As 2 (BNFA) single crystals with 0.19 ≤ x ≤ 0.34 have been investigated with the complementary muon-spin-rotation ( μ SR ) and infrared spectroscopy techniques. The focus has been on the different antiferromagnetic states in the underdoped regime and their competition with superconductivity,...

Université de Fribourg

Superconducting and antiferromagnetic properties of dual-phase V3Ga

Jamer, Michelle E. ; Wilfong, Brandon ; Buchelnikov, Vasiliy D. ; Sokolovskiy, Vladimir V. ; Miroshkina, Olga N. ; Zagrebin, Mikhail A. ; Baigutlin, Danil R. ; Naphy, Jared ; Assaf, Badih A. ; Lewis, Laura H. ; Pulkkinen, Aki ; Barbiellini, Bernardo ; Bansil, Arun ; Heiman, Don

In: Applied Physics Letters, 2020, vol. 117, no. 6, p. 062401

The binary compound V3Ga can exhibit two near-equilibrium phases, the A15 structure that is superconducting and the Heusler D03 structure that is semiconducting and antiferromagnetic. Density functional theory calculations show that these two phases are nearly degenerate, being separated in energy by only ±10 meV/atom. Our magnetization measurements on bulk-grown samples show ...

Université de Fribourg

Superconducting optical response of photodoped Mott insulators

Li, J. ; Golez, D. ; Werner, Philipp ; Eckstein, M.

In: Modern Physics Letters B, 2020, vol. 34, no. 19n20, p. 2040054

Ultrafast laser pulses can redistribute charges in Mott insulators on extremely short time scales, leading to the fast generation of photocarriers. It has recently been demonstrated that these photocarriers can form a novel η-paired condensate at low temperatures, featuring a staggered superconducting pairing field. In this conference paper, we discuss the origin of the η-paired hidden...

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

Infrared spectroscopy study of the in-plane response of ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6.6}$ in magnetic fields up to 30 Tesla

Lyzwa, Fryderyk ; Xu, Bing ; Maršík, Premysl ; Sheveleva, Evgeniia ; Crassee, I. ; Orlita, M. ; Bernhard, Christian

In: Physical Review Research, 2020, vol. 2, no. 2, p. 023218

With terahertz and infrared spectroscopy we studied the in-plane response of an underdoped, twinned YBa2Cu3O6.6 single crystal with Tc=58(1)K in high magnetic fields up to B=30 Tesla (T) applied along the c axis. Our goal was to investigate the field-induced suppression of superconductivity and to observe the signatures of the three-dimensional (3D) incommensurate copper charge density wave...

Université de Fribourg

Backfolded acoustic phonons as ultrasonic probes in metal-oxide superlattices

Lyzwa, Fryderyk ; Chan, A. ; Khmaladze, Jarji ; Fürsich, K. ; Keimer, B. ; Bernhard, Christian ; Minola, M. ; Mallett, Benjamin P. P.

In: Physical Review Materials, 2020, vol. 4, no. 4, p. 043606

Ultrasonics have been an incisive probe of internal interfaces in a wide variety of systems ranging from stars to solids. For thin-film structures, however, ultrasound is largely ineffective because the signal is dominated by the substrate. Using confocal Raman spectromicroscopy, we show that multiple reflection of sound waves at internal interfaces of a metal-oxide superlattice generates...