TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)

In this paper, we describe a numerical method for an electromagnetic phenomenon in type-II superconductors containing pins. Models of type-II superconductors containing pins use the eddy current problem of Maxwell's equations together with nonlinear constitutive relationships between the electric field (E) and the current density (J). The E-J relationship must lead to basic phenomena of superconductors such as the zero-resistance, flux flow, flux creep, hysteresis and magnetization. As typical models of the E-J relationship in superconductors, the critical state model, the power law “n-value model” and the percolation model are presented. Additionally, as an example, we introduce a superconducting slab, a magnetic shielding type of superconducting fault current limiter and a screening field in a HTS pancake coil.

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BaHfO₃ nanorod doped SmBa₂Cu₃O_y films were deposited on LaAlO₃ (001) substrates using pulsed-laser deposition (PLD). An alternating target (ALT) technique was used as the BaHfO₃ supply method. Two films were grown at 910 and 830ºC using a conventional PLD technique. One film was grown at 750ºC (an upper layer) on a seed layer using a low temperature growth (LTG) technique. Nanorod morphologies were analyzed using a scanning transmission electron microscopy (STEM) with an energy dispersive X-ray spectroscopy. It was found that the nanorod morphology varied by changing the growth temperature and the underlying structure. It was found that the critical current properties qualitatively corresponded to the nanorod morphology. In the case of straight, continuous nanorods, a magnetic field for the maximum value of global pinning force and the matching field estimated by a plan-view STEM analysis were consistent. We discussed the parameters for the control of nanorod morphology including the growth temperature and the underlying structure which were confirmed as the parameters in this experiment.

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