Electrical transport properties of random binary networks composed of high-T_c superconductor Bi₂Sr₂Ca₂Cu₃O_10+x (Bi2223) microparticles and half-metal ferromagnet La_2/3Sr_1/3MnO₃ (LSMO) nanoparticles have been investigated. The experimental current-voltage characteristics of bulk samples of nanocomposites with a volumetric content of 4:1 components are well described by the Berezinsky–Kosterlitz–Thouless (BKT) model for two-dimensional (2D) superconductors undergoing a superconducting transition. The observed 2D-like behavior of the three-dimensional transport properties of the nanocomposite is most likely associated with two different physical spatial scales involved in the formation of the properties of the nanocomposite: a significant difference between the geometric dimensions of the constituent components and the appearance of a triplet superconducting state induced by the proximity effect in semi-metallic manganite LSMO contacting Bi2223. Below the Bi2223 superconducting transition temperature, bulk resistive losses in the nanostructures are determined by the current flowing through ferromagnetic LSMO nanoparticles that cover Bi2223 microgranules. As temperature decreases, proximity-induced superconducting transition in the effectively 2D surface of LSMO nanoparticles covering Bi2223 microgranules reveals itself as the topological BKT-like superconducting transition in the bulk sample.

中文翻译：

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二维Berezinskii-Kosterlitz-三维Bi2Sr2Ca2Cu3O10+x:(La,Sr)MnO3纳米复合材料中的Thouless拓扑相变

的高组成的二进制随机网络的电输运性质Ť _Ç超导体的Bi ₂的Sr ₂的Ca ₂的Cu ₃ ø _{10+ X}（的Bi2223）微粒和半金属铁磁体的La _2/3的Sr _1/3的MnO ₃(LSMO) 纳米粒子已被研究。Berezinsky-Kosterlitz-Thouless (BKT) 模型对经历超导转变的二维 (2D) 超导体模型很好地描述了体积含量为 4:1 的纳米复合材料块状样品的实验电流-电压特性。观察到的纳米复合材料三维传输特性的 2D 样行为很可能与参与纳米复合材料特性形成的两个不同物理空间尺度有关：组成成分的几何尺寸与纳米复合材料的几何尺寸之间的显着差异。在半金属锰矿 LSMO 接触 Bi2223 中由邻近效应引起的三重超导态的出现。在 Bi2223 超导转变温度以下，纳米结构中的体电阻损失由流过覆盖 Bi2223 微粒的铁磁 LSMO 纳米颗粒的电流决定。随着温度降低，覆盖 Bi2223 微粒的 LSMO 纳米粒子的有效二维表面中的邻近诱导超导转变显示为大块样品中的拓扑 BKT 类超导转变。