Intrinsic pinning and the critical current scaling of clean epitaxial Fe(Se,Te) thin films

TL;DR

This paper investigates the intrinsic pinning and critical current behavior of clean Fe(Se,Te) thin films, revealing a short coherence length, order parameter modulation, and successful anisotropic scaling of Jc with implications for superconducting properties.

Contribution

It provides new insights into intrinsic pinning mechanisms and critical current scaling in Fe(Se,Te) thin films, using detailed transport measurements and anisotropic Ginzburg Landau modeling.

Findings

Short out-of-plane coherence length of 0.2 nm

Inverse correlation between N exponent and Jc at 4 K

Successful angular scaling of Jc using anisotropic Ginzburg Landau approach

Abstract

We report on the transport properties of clean, epitaxial Fe(Se,Te) thin films prepared on Fe-buffered MgO (001) single crystalline substrates by pulsed laser deposition. Near Tc a steep slope of the upper critical field for H||ab was observed (74.1 T/K), leading to a very short out-of-plane coherence length, \xi c, of 0.2 nm, yielding 2\xi c(0) approximately 0.4 nm. This value is shorter than the interlayer distance (0.605 nm) between Fe-Se(Te) planes, indicative of modulation of the superconducting order parameter along the c-axis. An inverse correlation between the power law exponent N of the electric field-current density (E-J) curve and the critical current density, Jc, has been observed at 4 K, when the orientation of H was close to the ab-plane. These results prove the presence of intrinsic pinning in Fe(Se,Te). A successful scaling of the angular dependent Jc and the corresponding exponent N can be realized by the anisotropic Ginzburg Landau approach with appropriate \Gamma values 2~3.5. The temperature dependence of \Gamma behaves almost identically to that of the penetration depth anisotropy.