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

Coexisting multiple order parameters in single-layer LuMnO3 films

Schneider, Christof W. ; Mukherjee, Saumya ; Shimamoto, Kenta ; Das, Saikat ; Luetkens, Hubertus ; White, Jonathan S. ; Bator, Matthias ; Hu, Yi ; Stahn, Jochen ; Prokscha, Thomas ; Suter, Andreas ; Salman, Zaher ; Kenzelmann, Michel ; Lippert, Thomas ; Niedermayer, Christof

In: Physical Review B, 2016, vol. 94, no. 5, p. 054423

Magnetoelectric multiferroics hold great promise for electrical control of magnetism or magnetic control of ferroelectricity. However, single phase ferroelectric materials with a sizeable ferromagnetic magnetization are rare. Here, we demonstrate that a single- phase orthorhombic LuMnO3 thin film features coexisting magnetic and ferroelectric orders. The temperature dependence of the...

Université de Fribourg

Atomic-resolution studies of epitaxial strain release mechanisms in $\mathrm{L}{\mathrm{a}}_{1.85}\mathrm{S}{\mathrm{r}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4}/\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{C}{\mathrm{a}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}$ superlattices

Biškup, N. ; Das, Saikat ; Gonzalez-Calbet, J. M. ; Bernhard, Christian ; Varela, M.

In: Physical Review B, 2015, vol. 91, no. 20, p. 205132

In this paper we present an atomic-resolution electron microscopy study of superlattices (SLs) where the colossal magnetoresistant manganite La0.67Ca0.33MnO3 (LCMO) and the high critical temperature superconducting cuprate La1.85Sr0.15CuO4 (LSCO) are combined. Although good quality epitaxial growth can be achieved, both the choice of substrate and the relatively large lattice mismatch between...

Université de Fribourg

Effect of combined addition of graphene oxide and citric acid on superconducting properties of MgB₂Effect of combined addition of graphene oxide and citric acid on superconducting properties of MgB₂

Sudesh ; Das, Saikat ; Bernhard, Christian ; Varma, G. D.

In: Physica C: Superconductivity and its Applications, 2015, vol. 509, p. 49–55

In the present work, polycrystalline samples with compositions MgB₂ + 3wt% GO + x wt% C₆H₈O₇ (x = 0, 5 and 10) have been synthesized to study the effect of combined addition of graphene oxide (GO) and citric acid (C₆H₈O₇) on superconducting properties of MgB₂. X-ray diffraction studies show the formation of hexagonal crystal structure of MgB₂ with space...

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

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 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

Strain-induced ferromagnetism in antiferromagnetic LuMnO₃ thin films

White, J. S. ; Bator, M. ; Hu, Yanqing ; Luetkens, H. ; Stahn, J. ; Capelli, S. ; Das, Saikat ; Döbeli, M. ; Lippert, Th. ; Malik, Vivek Kumar ; Martynczuk, J. ; Wokaun, A. ; Kenzelmann, M. ; Niedermayer, Ch. ; Schneider, C. W.

In: Physical Review Letters, 2013, vol. 111, no. 3, p. 037201

Single phase and strained LuMnO₃ thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the...

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