Manifestation of unusual size effects in granular thin films prepared by pulsed laser deposition. (November 2016)

• Record Type: Journal Article
• Authors: Sergeenkov, S.; Cichetto, L.; Diaz, J.C.C.A.; Bastos, W.B.; Longo, E.; Araújo-Moreira, F.M.
• Is Part Of: Journal of physics and chemistry of solids. Volume 98(2016:Nov.)
• Page Start: 38
• Page End: 42
• Publication Date: 2016-11
• Subjects: Nickelates -- Thin films -- Pulsed laser deposition -- Resistivity -- Crossover; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2016.06.003
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: We demonstrate manifestation of some rather unusual size effects in granular thin films prepared by a pulsed laser deposition technique. We observed that the temperature dependence of resistivity ρ ( T ) notably depends on the relation between the grain size R g and the film thickness d . Namely, more granular LaNiO3 thin films (with small values of R g ) grown on LaAlO3 substrate are found to follow a universal ρ ( T ) ∝ T 3 / 2 law for all the measured temperatures. While less granular thin films (with larger values of R g ), exhibit a more complicated behavior accompanied by a clear-cut crossover (around T cr = 200 K ), from ρ ( T ) ∝ T 3 / 2 (for 20 K < T < 200 K ) to ρ ( T ) ∝ T (for 200 K < T < 300 K ). The obtained results are attributed to manifestation of the finite temperature size effects (when an average grain size R g becomes comparable with the thermal de Broglie wavelength Λ ) leading to the crossover temperature T cr ∝ ( d / R g ) 2 . Abstract : Highlights: Unusual size effects are observed in granular thin films prepared by pulsed laser deposition. The obtained results are attributed to manifestation of the finite temperature size effects.