Thomas Qureishy; Yue Zhao; Yan Xu
Abstract
Magneto-optical imaging of YBa2Cu3O7-δ films with high critical current density, synthesized by a cost-effective metal organic decomposition technique reveals inhomogeneous flux penetration in the specimens in the form of thin parallel lines. The origin of such a stripy pattern and its dependence ...
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Magneto-optical imaging of YBa2Cu3O7-δ films with high critical current density, synthesized by a cost-effective metal organic decomposition technique reveals inhomogeneous flux penetration in the specimens in the form of thin parallel lines. The origin of such a stripy pattern and its dependence on the sample preparation conditions and state of substrate is discussed. The stripes reflect accumulation of planar defects forming parallel lines of reduced in-plane critical current density, jc, perpendicular to planar defects and enhanced jc parallel to them. Such channel-like reduction and corresponding enhancement of jc is especially expressed in a sample deposited on vicinal substrate, which, as a consequence, demonstrates global temperature-dependent in-plane anisotropy with an anisotropy ratio up to 2.4. The directional enhancement of critical current density due to planar defects could be beneficial for practical use of superconducting films.
Sachin Pathak;Manish Sharma
Abstract
Arrays of magnetic nanowires electrodeposited into nano-channel templates have attracted a lot of attention and research efforts in recent years. They are a promising system for perpendicular magnetic recording media. A major issue regarding the fabrication of such nanowires is the interplay between ...
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Arrays of magnetic nanowires electrodeposited into nano-channel templates have attracted a lot of attention and research efforts in recent years. They are a promising system for perpendicular magnetic recording media. A major issue regarding the fabrication of such nanowires is the interplay between the structure and magnetic properties. In this paper template-assisted electrodeposition technique using a three-electrode electrochemical cell is used to produce high density cobalt nanomaterial arrays with cylindrical shapes. The morphology of the samples is investigated by means of Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The length and average diameter of Cobalt nanowire arrays was found 4–15 µm and ~300 nm, respectively. The structural characteristic of the samples is examined using XRD and EDX, which confirm the hexagonal closely packed cobalt array structures. Magnetic property measurements show the influence of morphology on the magnetic properties of the arrays. Magnetic characterizations were carried out by Magneto-optical Kerr Effect (MOKE) and Electron paramagnetic resonance (EPR). The experimental results suggest close agreement with the resonance field seen in micro-magnetic modelling. We have calculated the resonance field for single nanowires with different length and for an array of seven nanowires. It is shown that the resonance field varies with the length, the interaction strength and also the spacing of the nanowires.