Growth of (Cu,C)Ba₂Ca₂Cu₃O_9±δ thin films on flexible Hastelloy tapes

Abstract The applications of superconducting cable or magnet require that the superconductors are made into wires or tapes. For cuprate superconductors, this is a big challenge because of the friability and short coherence length of the materials; weak links are easy to be formed at the grain boundaries hindering the flowing of the supercurrent. One of the ways is to fabricate superconducting films on flexible metallic tapes with oxide buffer layers. The successful one so far is the REBa 2 Cu 3 O 7 (RE = rare earth elements) films in tape form, as called the coated conductors. While the superconducting transition temperature of REBCO system is limited to around 90 K. Here we report the successful fabrication of another new non-toxic superconducting film, namely (Cu,C)Ba 2 Ca 2 Cu 3 O <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>9</mml:mn> <mml:mo>±</mml:mo> <mml:mi>δ</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> on these flexible metallic tapes with LaMnO 3 and CeO 2 as the top buffer layers. The onset superconducting transition occurs at 112 and 110 K, and the zero-resistance transition temperatures are about 96 and 98 K, respectively. The temperature dependent resistivity under magnetic fields in different directions reveals a relatively small anisotropy. Further optimization of the films will improve the zero resistance transition temperature, thus can also improve the characteristic properties for applications. Our results show that the (Cu,C)Ba 2 Ca 2 Cu 3 O <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>9</mml:mn> <mml:mo>±</mml:mo> <mml:mi>δ</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> is a promising candidate material for the high power applications in liquid nitrogen temperature region.