LTG法を用いて作製したSm_<1+x>Ba_<2-x>Cu_3O_y薄膜の配向性と成長様式 Orientation and Crystal Growth Mode in Sm_<1+x>Ba_<2-x>Cu_3O_y Films Prepared by a Low Temperature Growth Technique
We have reported high-<i>J</i><sub>c</sub> Sm<sub>1+<i>x</i></sub>Ba<sub>2-<i>x</i></sub>Cu<sub>3</sub>O<sub><i>y</i></sub> (SmBCO) films prepared by a low-temperature growth (LTG) technique. Despite the low-substrate temperature, the LTG-SmBCO films showed complete <i>c</i>-axis orientation and cube-on-cube texture. In addition, the LTG-SmBCO films showed a <i>J</i><sub>c</sub> of 0.28 MA/cm<sup>2</sup> (77 K, <i>B</i>//<i>c</i>, <i>B</i>=5 T), because these included high-dislocation densities and nanosize low-<i>T</i><sub>c</sub> particles. In this study, we discuss the mechanism of <i>c</i>-axis orientation and crystal growth for high-<i>J</i><sub>c</sub> LTG-SmBCO films. We newly suggest a model for "Nucleated growth on <i>c</i>-axis oriented Seed layer (NCS)" to understand the <i>c</i>-axis orientation mechanism for LTG-SmBCO films. Based on the NCS model, when the LTG-SmBCO films nucleated on a seed layer have two-dimensional (2D) nuclei with a 1 unit SmBCO step cell height, the interfacial energy between the nucleus and the seed layer and the critical Gibbs free energy of the nucleus are lower than those of PLD-SmBCO films. Therefore, the LTG-SmBCO films show high crystal quality and a wide processing window for biaxial orientation. We suggest that the LTG technique is effective for not only increasing <i>J</i><sub>c</sub> in magnetic fields, but also improving the processing window and crystal quality.
- 低温工学 = Journal of the Cryogenic Society of Japan
低温工学 = Journal of the Cryogenic Society of Japan 42(2), 47-55, 2007-02-25
CRYOGENICS AND SUPERCONDUCTIVITY SOCIETY OF JAPAN