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

Magneto-Optics of Spontaneous and Field Induced Vortices in Twinned YBa2\text{}_{2}Cu3\text{}_{3}O7−δ\text{}_{7-δ}/La1−x\text{}_{1-x}Srx\text{}_{x}MnO3\text{}_{3} Bilayers

The electromagnetic coupling between the magnetic and the superconducting layers in perovskite heterostructures is investigated by means of the magneto-optical technique. The quantitative imaging of the magnetic field distribution allows the high-resolution reconstruction of local supercurrent density. Two phenomena arising from the coupling between manganite layer and the YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ superconducting film deposited on top are addressed, i.e., the local effects of the electronic coupling between the compounds and the interaction between the manganite magnetic moments and the vortices in the superconductor. The first issue can be quantified in terms of the local superfluid density depression/enhancement in correspondence to the underlying magnetic structure, both domains and domain walls (in dependence on the orientation and sign of the local magnetization) and of the spontaneous, macroscopic screening current loops generated by the manganite domain walls. The interaction between the local manganite magnetization and the superconducting vortices is also influenced by structural defects because they modulate the magnetic pattern of the manganite. Different channelling phenomena in correspondence to the natural twin boundaries of the substrate, but locally magnetized by pinned domain walls of the manganite on their locations, are recognized

Magneto-Optics of Spontaneous and Field Induced Vortices in Twinned YBa 2

The electromagnetic coupling between the magnetic and the superconducting layers in perovskite heterostructures is investigated by means of the magneto-optical technique. The quantitative imaging of the magnetic field distribution allows the high-resolution reconstruction of local supercurrent density. Two phenomena arising from the coupling between manganite layer and the YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ superconducting film deposited on top are addressed, i.e., the local effects of the electronic coupling between the compounds and the interaction between the manganite magnetic moments and the vortices in the superconductor. The first issue can be quantified in terms of the local superfluid density depression/enhancement in correspondence to the underlying magnetic structure, both domains and domain walls (in dependence on the orientation and sign of the local magnetization) and of the spontaneous, macroscopic screening current loops generated by the manganite domain walls. The interaction between the local manganite magnetization and the superconducting vortices is also influenced by structural defects because they modulate the magnetic pattern of the manganite. Different channelling phenomena in correspondence to the natural twin boundaries of the substrate, but locally magnetized by pinned domain walls of the manganite on their locations, are recognized