High field vortex phase diagram of Fe( Se, Te) thin films

We report on the ( H; T) vortex phase diagram up to 35 T of Fe( Se, Te) thin films deposited on CaF2 substrates as determined by resistivity, Nernst effect and critical current measurements. We found the presence of a large region where the vortex is firmly pinned, allowing the adoption of chalcogenides for low temperature but extremely high magnetic field applications. The fact that high critical current density values-larger than 1 MA cm 2 in self-field and liquid helium-are reached together with a very weak dependence on the magnetic field and a complete isotropy, joined with the very high rigidity of the vortex lattice at very high field, makes the Fe( Se, Te) phase very promising for low temperature ( 6 4.2 K) and high field ( >= 25 T) applications.