Moura K O, Pirota K R, Béron F, Jesus C B R, Rosa P F S, Tobia D, Pagliuso P G, Lima O F de
Instituto de Física Gleb Wataghin, UNICAMP, Campinas, SP, 13083-859, Brazil.
Programa de Pós-Graduação em Física, Campus Prof. José Aluísio de Campos, UFS, 49100-000, São Cristóvão, SE, Brazil.
Sci Rep. 2017 Nov 10;7(1):15306. doi: 10.1038/s41598-017-15738-2.
Samples of nanostructured β-Ga wires were synthesized by a novel method of metallic-flux nanonucleation. Several superconducting properties were observed, revealing the stabilization of a weak-coupling type-II-like superconductor ([Formula: see text] [Formula: see text] 6.2 K) with a Ginzburg-Landau parameter [Formula: see text] = 1.18. This contrasts the type-I superconductivity observed for the majority of Ga phases, including small spheres of β-Ga with diameters near 15 μm. Remarkably, our magnetization curves reveal a crossover field [Formula: see text], where we propose that the Abrikosov vortices are exactly touching their neighbors inside the Ga nanowires. A phenomenological model is proposed to explain this result by assuming that only a single row of vortices is allowed inside a nanowire under perpendicular applied field, with an appreciable depletion of Cooper pair density at the nanowire edges. These results are expected to shed light on the growing area of superconductivity in nanostructured materials.
通过一种新型的金属助熔剂纳米成核方法合成了纳米结构的β-Ga线样品。观察到了几种超导特性，揭示了一种弱耦合类II型超导体（[公式：见正文][公式：见正文]6.2 K）的稳定性，其金兹堡-朗道参数[公式：见正文]=1.18。这与在大多数Ga相中观察到的I型超导形成对比，包括直径接近15μm的β-Ga小球。值得注意的是，我们的磁化曲线揭示了一个交叉场[公式：见正文]，我们提出在Ga纳米线内部阿布里科索夫涡旋恰好与它们的相邻涡旋接触。提出了一个唯象模型来解释这一结果，假设在垂直施加的场下纳米线内部只允许有单排涡旋，并且纳米线边缘的库珀对密度有明显的耗尽。这些结果有望为纳米结构材料中超导性这一不断发展的领域提供启示。
