Atypically robust superconductivity obtained by alloyage of non-superconducting Fe_1.1Te with 2H-NbSe₂

The [Fe_1.1Te +y·NbSe₂] composite samples (0 ⩽y⩽ 1.2) have been synthesized for the first time by alloyage of the non-superconducting antiferromagnetic iron telluride and superconducting niobium diselenide. The samples obtained were studied by means of x-ray diffraction, electrical resistivity and magnetization measurements. It has been found that in the range of 0.04 ⩽y⩽ 1.2, superconductivity withT_c∼ 12 K coexists with antiferromagnetic order. Despite that in pure 2H-NbSe₂the transition temperature does not exceedT_c∼ 7.2 K, the critical temperature in composite samples is significantly higher, even in compositions with the dominant NbSe₂phase. Atypically rigid superconductivity is observed across the entire NbSe₂concentration range, which is attributed to the multiphase and heterogeneous state of the samples, as well as the influence of interface effects at the phase boundaries. Since the observed effect differs significantly from standard substitutions on the chalcogen and/or metallic sublattices, which implies the search for other explanations of the superconducting state, the obtained results seem important for further engineering and design of complex superconducting systems based on bulk samples.