Biaxial texture establishment and evolution in IBAD-MgO films under different ion-to-atom ratios

MgO is a critical layer for the high-temperature superconducting coated conductor whose quality and performance greatly depend on the texturization of the MgO layer. In this paper, we have successfully grown MgO thin films on Y2O3 seed layers by the ion beam-assisted deposition (IBAD) method and systematically investigated the effects of ion-to-atom ratios (IARs) on the texture evolution of MgO films. It was found that better textured IBAD-MgO films could be obtained at thinner thickness with the increase of IAR. At low IARs of 0.2, 0.34, and 0.47, biaxial texture without c-axis tilting features could be observed in MgO films with thicknesses up to 50-60 nm, which is the highest value in our study. On the other hand, for high IARs of 0.66 and 0.79, the biaxial texture of MgO films was optimized at 13 nm and 7 nm, but completely disappeared at 26 nm and 12 nm, respectively. The differentiation in the texture evolution process under different IARs provides a crucial reference for elucidating the growth mechanism of IBAD-MgO. Moreover, these unambiguous experimental results also provide an excellent reference for the industrial production of HTS-coated conductors.