Abstract
We report on measurements of electric transport and voltage noise in FeTeSe epitaxial thin films. Detailed structural investigations demonstrate the high quality of the samples, also testified by a superconducting transition temperature of K, larger than the value observed for bulk compounds. An unusual dependence of the 1/ noise is found by varying the applied voltage and the temperature. Above a threshold voltage the 1/ noise shows a nonquadratic dependence on applied voltage with a temperature-dependent exponent. Conversely, at low voltages the 1/ noise amplitude follows always a quadratic law. In the superconductive transition region, a simple percolative model allows one to estimate the dimensionality of the system, which is found to be two-dimensional, with a critical exponent similar to values reported for other high- superconductors. The experimental findings on noise properties give evidence of unusual transport processes, occurring in this new superconducting material, and can provide useful information on possible conduction mechanisms.
- Received 12 January 2011
DOI:https://doi.org/10.1103/PhysRevB.83.134523
©2011 American Physical Society