Irreversible structure transitions in Gd monolayers on Mo(112)

• Published in: The European physical journal. B, Condensed matter physics Condensed matter physics, 2009-09, Vol.71 (1), p.47-54
• Main Authors: Fedorus, A. G., Mitryaev, A. A., Naumovets, A. G.
• Format: Article
• Language: English
• Subjects: Complex Systems; Condensed Matter Physics; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Fluid- and Aerodynamics; Phase transitions and critical phenomena; Physics; Physics and Astronomy; Solid State and Materials; Solid State Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2009-00285-1

Low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and contact potential difference (CPD) methods have been used to investigate the structure of Gd monolayers deposited on Mo(112) at T = 78 K and the changes upon annealing in a wide temperature range, up to the beginning of desorption. In the submonolayer coverage range (θ < 0.67), the film structures p(1.3×1) and p(2×1) already formed at T = 78 K, testifying that Gd adatoms possess some mobility at rather low temperatures. The p(1.3×1) structure was found to appear at 0.07 < θ < 0.25, but it irreversibly turned into the p(2×1) structure when the annealing temperature, T an , exceeded 500 K. Above θ = 0.25, the p(2×1) structure emerged immediately at 78 K. Formation of step arrays was observed in the range of T an = 500–1200 K and is attributed to surface alloying. The suggestion of surface alloying is corroborated by data on annealing induced variations of the work function and Auger peak of Gd. In the coverage range 0.5 < θ < 0.67, the phase p(2×1) was found to coexist with the phase c(1.5×2), which corresponds to a physical monolayer. No evidence of surface alloy in the complete monolayer was revealed. Distinction between ordering scenarios for the systems Gd/Mo(1 1 2) and Dy/Mo(112) is discussed.