Abstract Two superconducting intermetallic compounds in the Ni-Bi system, namely NiBi and NiBi3, can be formed as result of interdiffusion, if Ni/Bi are produced as bilayers at room temperature by pulsed laser deposition (PLD). These two equilibrium phases are responsible for the observed superconductivity in this kind of bilayer material. Due to different behavior in external magnetic fields, there appear two-step superconducting transitions in the electrical transport measurements. In this work we studied the superconducting and magnetic properties of the Ni-Bi bilayers with the formation of the two intermetallic compounds, NiBi and NiBi3, which have similar Tc ~ 4.0 K but very different upper critical magnetic fields at zero temperature [Bc2(0)]. The magnetic hysteresis loops of the pure NiBi3 phase show the behavior of a weak type II superconductor without strong pinning effect. Upon formation of the NiBi phase caused by highly energetic atoms during pulsed laser deposition, strong pinning effects appeared in the hysteresis loops below Tc. The isotherm V(I) curves show that the residual Ni layer does not induce spontaneous vortices in the NiBi or NiBi3 phases.

中文翻译：

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Ni-Bi薄膜脉冲激光沉积过程中形成的超导相NiBi和NiBi3的磁性

摘要 如果在室温下通过脉冲激光沉积 (PLD) 将 Ni/Bi 制成双层，Ni-Bi 系统中的两种超导金属间化合物，即 NiBi 和 NiBi3，可以作为相互扩散的结果形成。这两个平衡相是在这种双层材料中观察到的超导性的原因。由于外部磁场的不同行为，在电输运测量中出现了两步超导跃迁。在这项工作中，我们通过形成两种金属间化合物 NiBi 和 NiBi3 研究了 Ni-Bi 双层的超导和磁性能，它们具有相似的 Tc ~ 4.0 K 但在零温度下的上临界磁场非常不同 [Bc2(0 )]。纯 NiBi3 相的磁滞回线显示出没有强钉扎效应的弱 II 型超导体的行为。在脉冲激光沉积过程中由高能原子引起的 NiBi 相形成后，在 Tc 以下的磁滞回线中出现了强烈的钉扎效应。等温线 V(I) 曲线表明残留的 Ni 层不会在 NiBi 或 NiBi3 相中引起自发涡流。