Suppression of Superconductivity in YBCO/LCMO Superlattices

The competition of superconductivity and magnetism in superlattices composed of alternating YBa$_2$Cu$_3$O$_{7-d}$ and La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ thin films is investigated using low-energy optical spectroscopy. The thickness of the superconducting YBCO layers is varied from 30 nm to 20 nm while the thickness of the magnetic LCMO layers is kept constant at 20 nm. We clearly observe that the superconducting condensate density in the superconducting state of superlattice is drastically reduced by the magnetic subsystem which may be connected with proximity effects that distort the gap symmetry and thus suppress superconductivity.Comment: 4 pages, 4 figure

Thin Films and Heterostructures of Layered Oxides: Preparation and Properties

A brief overview of the deposition and properties of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ (YBCO) based heterostructures is presented. Emphasis is placed on the assessment of the deposition process and the properties of practical thin films and heterostructures of layered oxides. Besides a reference to the literature we present our recent results concerning deposition, structural and magnetic properties of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ /RE$\text{}_{1-x}$A$\text{}_{x}$MnO$\text{}_{3}$ (YBCO/REMO) heterostructures

Magnetism and Superconductivity in Nd0.81\text{}_{0.81}Sr0.19\text{}_{0.19}MnO3\text{}_{3}/YBa2\text{}_{2}Cu3\text{}_{3}O7\text{}_{7} Superlattices

We report on the growth, structural and magnetic characterization of Nd$\text{}_{0.81}$Sr$\text{}_{0.19}$MnO$\text{}_{3}$/YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ (NSMO/YBCO) superlattices. The NSMO system for the doping level of x=0.19 is a ferromagnetic insulator. Multilayers with a fixed NSMO thickness of 13 unit cells and a varying YBCO layer thickness from 2 unit cells to 6 unit cells were sputtered on LaAlO$\text{}_{3}$ substrates. An onset of superconducting transition is seen starting from the multilayer with 3 unit cells of YBCO layer thickness. Hysteresis loops recorded above and below the superconducting transition show a signature of interlayer exchange coupling

Structural Properties of Co and CoFe Electrodes Forming a Magnetic Tunnel Junction

The M$\text{}_{1}$/MgO/M$\text{}_{2}$ trilayer tunnel magnetoresistance systems are studied by means of X-ray diffraction, NMR, and transmission electron microscopy techniques. As M$\text{}_{1}$ and M$\text{}_{2}$ electrodes we used Co, Fe, and CoFe layers. The growth mechanism and structural quality of both electrodes and of the epitaxial MgO barrier forming the magnetic tunnel junctions are experimentally examined. It is shown that the crystallographic coherence of magnetic tunnel junctions across the MgO barrier is significantly disturbed by imperfect crystal structure of magnetic electrodes. The NMR results indicate a difference in short-range order between bottom and top electrodes

Structural Properties of Co and CoFe Electrodes Forming a Magnetic Tunnel Junction

The M$\text{}_{1}$/MgO/M$\text{}_{2}$ trilayer tunnel magnetoresistance systems are studied by means of X-ray diffraction, NMR, and transmission electron microscopy techniques. As M$\text{}_{1}$ and M$\text{}_{2}$ electrodes we used Co, Fe, and CoFe layers. The growth mechanism and structural quality of both electrodes and of the epitaxial MgO barrier forming the magnetic tunnel junctions are experimentally examined. It is shown that the crystallographic coherence of magnetic tunnel junctions across the MgO barrier is significantly disturbed by imperfect crystal structure of magnetic electrodes. The NMR results indicate a difference in short-range order between bottom and top electrodes

Superconductivity and Magnetism in Nd 0.5

We report the synthesis and characterization of Nd$\text{}_{0.5}$Sr$\text{}_{0.5}$MnO$\text{}_{3}$/YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ superlattices. X-ray diffraction studies show that the superlattices are [001] oriented. We observe that the magnetic ground state of Nd$\text{}_{0.5}$Sr$\text{}_{0.5}$MnO$\text{}_{3}$ system in a multilayered structure is strongly dependent on the substrate

Superconductivity and Magnetism in Nd0.5\text{}_{0.5}Sr0.5\text{}_{0.5}MnO3\text{}_{3}/YBa2\text{}_{2}Cu3\text{}_{3}O7\text{}_{7} Superlattices

We report the synthesis and characterization of Nd$\text{}_{0.5}$Sr$\text{}_{0.5}$MnO$\text{}_{3}$/YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ superlattices. X-ray diffraction studies show that the superlattices are [001] oriented. We observe that the magnetic ground state of Nd$\text{}_{0.5}$Sr$\text{}_{0.5}$MnO$\text{}_{3}$ system in a multilayered structure is strongly dependent on the substrate