Abstract
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 \(1\times 1\) \(\mu\) m \({}^{2}\) area and 7–10 nm in a \(10\times 10\) \(\mu\) 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: \(H_{c2}^{\parallel ab}(0)\approx 68\) T and \(H_{c2}^{\perp ab}(0)\approx 51\) T for different orientations of the magnetic field relative to the crystallographic planes of the film. The corresponding value of the anisotropy \(\gamma\) 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 \(\xi_{ab}(0)\approx 2.5\) nm, \(\xi_{c}(0)\approx 1.9\) nm. The critical current density was measured and found to be at the level of \(2.1\times 10^{4}\) A/cm \({}^{2}\) (contact method) and \(2.3\times 10^{4}\) 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.
