Miura Masashi, Eley Serena, Iida Kazumasa, Hanzawa Kota, Matsumoto Jumpei, Hiramatsu Hidenori, Ogimoto Yuki, Suzuki Takumi, Kobayashi Tomoki, Ozaki Toshinori, Kurokawa Hodaka, Sekiya Naoto, Yoshida Ryuji, Kato Takeharu, Okada Tatsunori, Okazaki Hiroyuki, Yamaki Tetsuya, Hänisch Jens, Awaji Satoshi, Maeda Atsutaka, Maiorov Boris, Hosono Hideo
Graduate School of Science and Technology, Seikei University, Tokyo, Japan.
National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM, USA.
Nat Mater. 2024 Oct;23(10):1370-1378. doi: 10.1038/s41563-024-01952-7. Epub 2024 Jul 18.
Iron-based 1111-type superconductors display high critical temperatures and relatively high critical current densities J. The typical approach to increasing J is to introduce defects to control dissipative vortex motion. However, when optimized, this approach is theoretically predicted to be limited to achieving a maximum J of only ∼30% of the depairing current density J, which depends on the coherence length and the penetration depth. Here we dramatically boost J in SmFeAsOH films using a thermodynamic approach aimed at increasing J and incorporating vortex pinning centres. Specifically, we reduce the penetration depth, coherence length and critical field anisotropy by increasing the carrier density through high electron doping using H substitution. Remarkably, the quadrupled J reaches 415 MA cm, a value comparable to cuprates. Finally, by introducing defects using proton irradiation, we obtain high J values in fields up to 25 T. We apply this method to other iron-based superconductors and achieve a similar enhancement of current densities.
铁基1111型超导体具有较高的临界温度和相对较高的临界电流密度J。提高J的典型方法是引入缺陷以控制耗散涡旋运动。然而，理论预测，当这种方法优化后，其所能达到的最大J仅为去配对电流密度J的约30%，而去配对电流密度J取决于相干长度和穿透深度。在此，我们采用一种旨在提高J并引入涡旋钉扎中心的热力学方法，显著提高了SmFeAsOH薄膜中的J。具体而言，我们通过用H替代进行高电子掺杂来增加载流子密度从而减小穿透深度、相干长度和临界场各向异性。值得注意的是，J增大了四倍，达到415 MA/cm²，这一数值与铜酸盐相当。最后，通过质子辐照引入缺陷，我们在高达25 T的磁场中获得了高J值。我们将此方法应用于其他铁基超导体，并实现了电流密度的类似增强。
