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 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

Superconductivity and charge-carrier localization in ultrathin ${\mathrm{La}}_{1.85}{\mathrm{Sr}}_{0.15}{\mathrm{CuO}}_{4}/{\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ bilayers

Sen, Kaushik ; Maršík, Premysl ; Das, Saikat ; Perret, E. ; Andres Prada, R. de ; Alberca, Aurora ; Biškup, N. ; Varela, M. ; Bernhard, Christian

In: Physical Review B, 2017, vol. 95, no. 21, p. 214506

La1.85Sr0.15CuO4/La2CuO4 (LSCO15/LCO) bilayers with a precisely controlled thickness of N unit cells (UCs) of the former and M UCs of the latter ([LSCO15_N/LCO_M]) were grown on (001)-oriented SrLaAlO4 (SLAO) substrates with pulsed laser deposition (PLD). X-ray diffraction and reciprocal space map (RSM) studies confirmed the epitaxial growth of the bilayers and showed that a [LSCO15_2/LCO_2]...

Université de Fribourg

Infrared ellipsometry study of photogenerated charge carriers at the (001) and (110) surfaces of $\mathrm{SrTi}{\mathrm{O}}_{3}$ crystals and at the interface of the corresponding $\mathrm{LaAl}{\mathrm{O}}_{3}/\mathrm{SrTi}{\mathrm{O}}_{3}$ heterostructures

Yazdi-Rizi, Meghdad ; Maršík, Premysl ; Mallett, Benjamin P. P. ; Sen, Kaushik ; Cerreta, A. ; Dubroka, Adam ; Scigaj, M. ; Sánchez, F. ; Herranz, G. ; Bernhard, Christian

In: Physical Review B, 2017, vol. 95, no. 19, p. 195107

With infrared (IR) ellipsometry and dc resistance measurements, we investigated the photodoping at the (001) and (110) surfaces of SrTiO3 (STO) single crystals and at the corresponding interfaces of LaAlO3/SrTiO3 (LAO/STO) heterostructures. In the bare STO crystals, we find that the photogenerated charge carriers, which accumulate near the (001) surface, have a similar depth profile and sheet...

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...

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

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

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...