The A15 structure of superconductors is a prototypical type-II superconductor that has generated considerable interest since the early history of superconducting materials. This paper discusses the superconducting properties of previously unreported V3−xCoxSi (0 ⩽ x ⩽ 0.30) alloys. It is found that the lattice parameter decreases with increasing cobalt-doped content and leads to an decreased residual resistivity ratio value of the V3−xCoxSi system. Meanwhile, the superconducting transition temperature (Tc) also decreases with increasing cobalt-doped content. Furthermore, the fitted data show that the increase of cobalt-doped content also reduces the lower/upper critical fields of the V3−xCoxSi system. Type-II superconductivity is demonstrated in all V3−xCoxSi samples. With higher Co-doped content, V3−xCoxSi (0.15 ⩽ x ⩽ 0.30) alloys may have superconducting and structural phase transitions in low-temperature regions. As the electron/atom ratio increases, the Tc variation trend of V3Si is as pronounced as in crystalline alloys and monotonically follows the trend observed for amorphous superconductors.
Wang J.,Ou X. L.,Zhang J.,Chen X. Y.,Zhao K.,Yang X. S.,Zhao Y.
Fe(Te,Se) is a simple, iron-based compound that is conducive to the study of superconductivity mechanisms and has potential for large-scale applications. At present, Fe(Te,Se) thin films are primarily prepared using the pulsed laser deposition method. Herein, FeTe 0.6 Se 0.4 films were grown by magnetron sputtering on CaF 2 substrates. The effect of sputtering pressure on the superconductivity of the film was investigated. Excessive pressure caused a higher iron content, which affected the superconductivity and prevented it from completely reaching a zero-resistance state. Δ T c was smaller for the film grown under 0.2 Pa, and its upper critical field reached 144.35 T, which indicates its greater application potential. Our results illustrated that sputtering pressure was a critical process parameter, which provided an important reference for future research to fabricate commercial iron-based superconducting tapes by magnetron sputtering.
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