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

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...

Université de Fribourg

Granular superconductivity and charge/orbital order in YBa 2 Cu 3 O 7 /manganite trilayers

Khmaladze, Jarji ; Sarkar, Subhrangsu ; Soulier, Mathias ; Lyzwa, Fryderyk ; Prada, R. de Andres ; Perret, Edith ; Mallett, Benjamin P. P. ; Minola, M. ; Keimer, B. ; Bernhard, Christian

In: Physical Review Materials, 2019, vol. 3, no. 8, p. 084801

We studied how the electronic, superconducting, and magnetic properties of YBa2Cu3O7/Nd1−x(Ca1−ySry )xMnO3 multilayers depend on the tolerance factor and the hole doping of the manganite. In particular, we investigated the granular superconducting state and the related magnetic-field-driven insulator-to- superconductor transition that was previously discovered in corresponding multilayers...

Université de Fribourg

Coupled Cu and Mn charge and orbital orders in YBa₂Cu₃O₇/Nd 0.65 (Ca 1-y Sr y ) 0.35 MnO₃ multilayers

Perret, Edith ; Monney, Claude ; Johnston, S. ; Khmaladze, Jarji ; Lyzwa, Fryderyk ; Gaina, Roxana ; Dantz, M. ; Pelliciari, Jonathan ; Piamonteze, C. ; Mallett, B.P.P. ; Minola, M. ; Keimer, B. ; Schmitt, Thorsten ; Bernhard, Christian

In: Communications Physics, 2018, vol. 1, no. 1, p. 45

The observation of a charge density wave in the underdoped cuprate high Tc superconductors (Cu-CDW) raised a debate about its relationship with superconductivity. In bulk YBa2Cu3O7−δ the Cu-CDW is incipient and mainly pinned by defects. Nevertheless, a large magnetic field can induce a true long-range Cu- CDW order as it suppresses superconductivity. An enhanced Cu-CDW order was also ...

Université de Fribourg

Structural, magnetic and electronic properties of pulsed-laser-deposition grown SrFeO 3− δ thin films and SrFeO 3− δ /La 2/3 Ca 1/3 MnO 3 multilayers

Perret, Edith ; Sen, Kaushik ; Khmaladze, Jarji ; Mallett, Benjamin P. P. ; Yazdi-Rizi, Meghdad ; Maršík, Premysl ; Das, Saikat ; Marozau, Ivan ; Uribe-Laverde, Miguel Angel ; Andrés Prada, R. de ; Strempfer, J. ; Döbeli, Max ; Biškup, N. ; Varela, M. ; Mathis, Y.-L. ; Bernhard, Christian

In: Journal of Physics: Condensed Matter, 2017, vol. 29, no. 49, p. 495601

We studied the structural, magnetic and electronic properties of ${\rm SrFeO}_{3- \delta}$ (SFO) thin films and ${\rm SrFeO}_{3-\delta}$ /${\rm La}_{2/3}$ ${\rm Ca}_{1/3}$ MnO3 (LCMO) superlattices that have been grown with pulsed laser deposition (PLD) on ${\rm La}_{0.3}$ ${\rm Sr}_{0.7}$ ${\rm Al}_{0.65}$ ${\rm Ta}_{0.35}$ ${\rm O}_{3}$ (LSAT) substrates. X-ray reflectometry and scanning ...

Université de Fribourg

Granular superconductivity and magnetic-field-driven recovery of macroscopic coherence in a cuprate/manganite multilayer

Mallett, Benjamin P. P. ; Khmaladze, Jarji ; Marsik, Premysl ; Perret, Edith ; Cerreta, A. ; Orlita, M. ; Biškup, N. ; Varela, M. ; Bernhard, Christian

In: Physical Review B, 2016, vol. 94, no. 18, p. 180503

We show that in Pr0.5La0.2Ca0.3MnO3/YBa2Cu3O7 (PLCMO/YBCO) multilayers the low temperature state of YBCO is very resistive and resembles that of a granular superconductor or a frustrated Josephson-junction network. Notably, a coherent superconducting response can be restored with a large magnetic field which also suppresses the charge-orbital order in PLCMO. This coincidence suggests that the...

Université de Fribourg

Terahertz ellipsometry study of the soft mode behavior in ultrathin SrTiO films

Marsik, Premysl ; Sen, Kaushik ; Khmaladze, Jarji ; Yazdi-Rizi, Meghdad ; Mallett, Benjamin P. P. ; Bernhard, Christian

In: Applied Physics Letters, 2016, vol. 108, no. 5, p. 052901

We present a combined study with time-domain terahertz and conventional far-infrared ellipsometry of the temperature dependent optical response of SrTiO₃thin films (82 and 8.5 nm) that are grown by pulsed-laser deposition on (La0.3Sr0.7) (Al0.65Ta0.35)O₃ (LSAT) substrates. We demonstrate that terahertz ellipsometry is very sensitive to the optical...