Effect of thermal annealing and irradiation damage on the superconducting critical temperature of nanocrystalline gamma-Mo2N thin films

S. SUAREZ; M. SIRENA; S. BENGIO; J. A. HOFER; N. HABERKORN; P. D. PEREZ

MATERIALS LETTERS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019 vol. 236 p. 252 - 256

0167-577X

We report on the influence of the disorder and stoichiometry in the resulting superconducting critical temperature of gamma-Mo2N thin films. Initially, three films (with Tc values of 7.6 K, 6.8 K and 6 K) were grown at room temperature by reactive sputtering, on Si (100) using different N2/(Ar+N2) mixtures. The influence of the thermal annealing up to 973 K and irradiation damage produced by 1 MeV Zr+(fluence up 2x10^14 cm-2) is analyzed. The Tc of pristine films remains unchanged for increasing irradiation doses up 2x10^14 cm-2. The Tc for annealed films decreases close to the value expected for bulk samples (5 K) for increasing the annealing temperature. Successive irradiations of the annealed films tend to increase their Tc up to its initial values (before annealing). The results indicate that the Tc in nanometric grain size gamma-Mo2N thin films is affected by both nitrogen stoichiometry and disorder at the atomic scale.