Enhancement of self-field critical current density by several-tens-MeV ion irradiation in YBa₂Cu₃O₇ films prepared by fluorine-free metal-organic deposition

Abstract

An up-to 63% enhancement in critical current density (Jc) was achieved for 1-μm-thick YBa2Cu3O7 (YBCO) films at self-field at 77 K by irradiation with 24-84 MeV Au ions. This enhancement is highly unusual, since in YBCO films, Jc at self-field (Jc sf) is generally insensitive to ion irradiation, unlike Jc in magnetic fields. Our observed film-thickness dependence of the irradiation effect and our microstructure imaging indicate that this rare observation is attributed to an extremely “clean” (i.e., less-disordered) microstructure in the top 700-nm of the layer of our 1-μm-thick films prepared via fluorine-free metal-organic deposition. Our results directly indicate that discontinuous 1D vortex-pinning centers (pins) that have the following features effectively enhance MA/cm2-order Jc sf at 77 K of YBCO films; namely, 5-10 nm in diameter, ~20 nm in size along a pin track, have a ~20 nm gap between the pins in a pin track, and are directed in the c-axis.

Effect of doping on evolution of He⁺ion irradiation defects and superconductivity in EuBa₂Cu₃O_7–δ superconducting strips

“…元素离子, 可避免额外的化学效应对带材超导电性 的影响 [19] . 学者们也开展了质子 [12,20] 、重离子 [21,22] 对REBCO带材的辐照效应研究, 证明低剂量离 子辐照能够提高超导体中微结构缺陷密度, 有效地 增加多种维度的磁通钉扎中心, 从而改善其超导性 能; 但过量辐照则导致超导正交相向非超导四方相 的相变、非晶无序化等现象, 使得T c 和J c 大幅降 低、超导电性严重损失. 同时有研究报道, 对中子 或重离子辐照的REBCO带材进行高温氧气退火 处理, 可以消除部分辐照缺陷, 恢复带材的超导电 性 [22][23][24] .…”