Characteristics of FeSe0.5Te0.5 Films on an Amorphous Substrate

For FeSeTe films on an amorphous dielectric substrate—K-208 grade glass—the surface morphology and elemental composition were investigated. The measured root-mean-square roughness values of the film surface were 4–6 nm in a 1× 1 μ m ² area and 7–10 nm in a 10× 10 μ m ² area. The determined elemental composition Fe 1.05 Se 0.5 Te 0.5 was found to be close to the stoichiometric ratio. Estimates were obtained for the values of the upper critical field: Hc2∥ ab(0)≈ 68 T and Hc2⊥ ab(0)≈ 51 T for different orientations of the magnetic field relative to the crystallographic planes of the film. The corresponding value of the anisotropy γ of the film properties is close to 1.3 and comparable to the results for such films on single-crystal substrates. The coherence lengths were found to be ξab(0)≈ 2.5 nm, ξc(0)≈ 1.9 nm. The critical current density was measured and found to be at the level of 2.1× 10⁴ A/cm ² (contact method) and 2.3× 10⁴ A/cm ² (contactless method—SQUID), in zero field at a temperature of 2 K. Estimates for the vortex activation energy $$U(H)$$ and the pinning force density were obtained. Predominance of pinning on correlated defects was demonstrated.