Université de Fribourg

Element-specific magnetization redistribution at ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}/{\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ interfaces

Alberca, Aurora ; Uribe-Laverde, Miguel Angel ; Windsor, Y. W. ; Ramakrishnan, M. ; Rettig, L. ; Marozau, Ivan ; Tonnerre, J-M. ; Stahn, J. ; Staub, U. ; Bernhard, Christian

In: Physical Review B, 2015, vol. 92, no. 17, p. 174415

We study the element-specific magnetic depth profiles of a YBa2Cu3O7/La2/3Ca1/3MnO3 (YBCO/LCMO) superlattice using soft x-ray resonant magnetic reflectometry (XRMR). This allows us to study the magnetic proximity effect (MPE) that is observed at the YBCO/LCMO interface, characterized by the occurrence of a depleted layer on the manganite side and an induced magnetization in the YBCO. Using the...

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...

Université de Fribourg

Structural, magnetic, and superconducting properties of pulsed-laser-deposition-grown ${\text{La}}_{1.85}$${\text{Sr}}_{0.15}$${\text{CuO}}_{4}$/${\text{La}}_{2/3}$${\text{Ca}}_{1/3}$${\text{MnO}}_{3}$ superlattices on (001)-oriented ${\text{LaSrAlO}}_{4}$ substrates

Das, Saikat ; Sen, Kaushik ; Marozau, Ivan ; Uribe-Laverde, Miguel Angel ; Biskup, N. ; Varela, M. ; Khaydukov, Y. ; Soltwedel, O. ; Keller, T. ; Döbeli, M. ; Schneider, C. W. ; Bernhard, Christian

In: Physical Review B, 2014, vol. 89, no. 9, p. 094511

Epitaxial La1.85Sr0.15CuO4/La2/3Ca1/3MnO3 (LSCO/LCMO) superlattices on (001)-oriented LaSrAlO4 substrates have been grown with pulsed laser deposition technique. Their structural, magnetic, and superconducting properties have been determined with in situ reflection high-energy electron diffraction, x-ray diffraction, specular neutron reflectometry, scanning transmission electron microscopy,...

Université de Fribourg

High bias anomaly in YBa₂Cu₃O7−x/LaMnO₃₊/YBa₂Cu₃O7−x superconductor/ferromagnetic insulator/superconductor junctions: Evidence for a long-range superconducting proximity effect through the conduction band of a ferromagnetic insulator

Golod, T. ; Rydh, A. ; Krasnov, V. M. ; Marozau, Ivan ; Uribe-Laverde, Miguel Angel ; Satapathy, Dillip Kumar ; Wagner, Th. ; Bernhard, Christian

In: Physical Review B, 2013, vol. 87, no. 13, p. 134520

We study the perpendicular transport characteristics of small superconductor/ferromagnetic insulator/superconductor (YBa₂Cu₃O7−x/LaMnO₃₊/YBa₂Cu₃O7−x) tunnel junctions. At a large bias voltage V∼1 V we observe a steplike onset of excess current that occurs below the superconducting transition temperature Tc and is easily suppressed by a...

Université de Fribourg

Influence of La and Mn vacancies on the electronic and magnetic properties of LaMnO₃ thin films grown by pulsed laser deposition

Marozau, Ivan ; Das, Proloy T. ; Döbeli, Max ; Storey, James G. ; Uribe-Laverde, Miguel A. ; Das, Saikat ; Wang, Chennan ; Rössle, Matthias ; Bernhard, Christian

In: Physical Review B, 2014, vol. 89, no. 17, p. 174422

With pulsed laser deposition, we have grown c axis oriented thin films of the nominal composition LaMnO3 (LMO) on LSAT(001) substrates. We find that, depending on the oxygen background pressure during growth, the LMO films contain sizeable amounts of La and/or Mn vacancies that strongly influence their electronic and magnetic properties. Specifically, we show that the Mn/La ratio can be...

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

Optical probe of ferroelectric order in bulk and thin-film perovskite titanates

Rössle, Matthias ; Wang, Chen Nan ; Maršík, Premysl ; Yazdi-Rizi, M. ; Kim, Kyung Wan ; Dubroka, Adam ; Marozau, Ivan ; Schneider, C. W. ; Humlíček, J. ; Baeriswyl, Dionys ; Bernhard, Christian

In: Physical Review B, 2013, vol. 88, no. 10, p. 104110

We have measured the temperature dependence of the direct band gap Eg in SrTiO₃ and BaTiO₃ and related materials with quantum-paraelectric and ferroelectric properties using optical spectroscopy. We show that Eg exhibits an anomalous temperature dependence with pronounced changes in the vicinity of the ferroelectric transition that can be...

Université de Fribourg

X-ray absorption study of the ferromagnetic Cu moment at the ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}/{\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ interface and variation of its exchange interaction with the Mn moment

Sen, Kaushik ; Perret, Edith ; Alberca, Aurora ; Uribe-Laverde, Miguel Angel ; Marozau, Ivan ; Yazdi-Rizi, M. ; Mallett, Benjamin P. P. ; Maršík, Premysl ; Piamonteze, C. ; Khaydukov, Yu N. ; Döbeli, Max ; Keller, T. ; Biškup, N. ; Varela, M. ; Vašátko, J. ; Munzar, Dominik ; Bernhard, Christian

In: Physical Review B, 2016, vol. 93, no. 20, p. 205131

With x-ray absorption spectroscopy and polarized neutron reflectometry we studied how the magnetic proximity effect at the interface between the cuprate high-TC superconductor YBa2Cu3O7 (YBCO) and the ferromagnet La2/3Ca1/3MnO3 (LCMO) is related to the electronic and magnetic properties of the LCMO layers. In particular, we explored how the magnitude of the ferromagnetic Cu moment on the YBCO...

Université de Fribourg

X-ray absorption spectroscopy study of the electronic and magnetic proximity effects in ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}/{\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ and ${\mathrm{La}}_{2$-${}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}/{\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ multilayers

Uribe-Laverde, Miguel Angel ; Das, Saikat ; Sen, Kaushik ; Marozau, Ivan ; Perret, E. ; Alberca, A. ; Heidler, J. ; Piamonteze, C. ; Merz, M. ; Nagel, P. ; Schuppler, S. ; Munzar, Dominik ; Bernhard, Christian

In: Physical Review B, 2014, vol. 90, no. 20, p. 205135

With x-ray absorption spectroscopy we investigated the orbital reconstruction and the induced ferromagnetic moment of the interfacial Cu atoms in YBa2Cu3O7/La2/3Ca1/3MnO3 (YBCO/LCMO) and La2−xSrxCuO4/La2/3Ca1/3MnO3 (LSCO/LCMO) multilayers. We demonstrate that these electronic and magnetic proximity effects are coupled and are common to these cuprate/manganite multilayers. Moreover, we show that...

Université de Fribourg

Depth profile of the ferromagnetic order in a YBa₂Cu₃O₇/La2/3Ca1/3MnO₃ superlattice on a LSAT substrate: A polarized neutron reflectometry study

Uribe-Laverde, Miguel Angel ; Satapathy, Dillip Kumar ; Marozau, Ivan ; Malik, Vivek Kumar ; Das, Saikat ; Sen, Kaushik ; Stahn, J. ; Rühm, A. ; Kim, Joo Young ; Keller, T. ; Devishvili, A. ; Toperverg, B. P. ; Bernhard, Christian

In: Physical Review B - Condensed Matter and Materials Physics, 2013, vol. 87, no. 11, p. 115105

Using polarized neutron reflectometry (PNR) we have investigated a [YBa₂Cu₃O₇(10 nm)/La2/3Ca1/3MnO₃(9 nm)]₁₀ (YBCO/LCMO) superlattice grown by pulsed laser deposition on a La0.3Sr0.7Al0.65Ta0.35O₃ (LSAT) substrate. Due to the high structural quality of the superlattice and the substrate, the specular reflectivity...