  Formation of vortices is a typical phenomenon of type-II superconductors
under magnetic fields (H). In contrast, type-I superconductors do not host
vortices because of their Meissner state. As rare cases, vortices have been
observed in intermediate states of type-I superconductors; in addition, the
recent observation of type-II superconductivity with vortices in a (originally
type-I) Pb crystal film at extremely low temperature (T) under H has opened new
pathway to study vortex physics. However, thermodynamic characteristics of such
type-II-like superconducting states with vortices in originally type-I element
superconductors have not been detected because of the lack of bulk example. In
this study, we investigated superconducting states of phase-separated Sn-Pb
solders using specific heat and magnetization to reveal magnetic-flux-trapping
mechanisms. Here, we show that Sn islands in the Sn-Pb solders exhibit
type-II-like superconducting states with vortices when the solders host
extremely high magnetic fluxes after field cooling. Furthermore, with
increasing T, the amount of trapped flux decreases, and the driving force of
the magnetic flux changes from type-II superconducting states of Sn to
supercurrent of Pb regions surrounding the Sn islands. The field-cooled Sn-Pb
solders are rich in physics of bulk vortex formation and anomalously enhanced
supercurrent in element (originally type-I) superconductors.
