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Real-time monitoring the growth of strained off-stoichiometric Ni x Fe3−xO4 ultrathin films on MgO(001)

DOI: 10.1063/5.0013925 DOI Help

Authors: J. Rodewald (Osnabrück University) , J. Thien (Osnabrück University) , T. Pohlmann (Osnabrück University; DESY Photon Science) , M. Hoppe (Osnabrück University; DESY Photon Science) , F. Bertram (DESY Photon Science) , K. Kuepper (Osnabrück University) , J. Wollschlager (Osnabrück University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Applied Physics Letters , VOL 117

State: Published (Approved)
Published: July 2020
Diamond Proposal Number(s): 16299

Abstract: NixFe3−x Ni x Fe 3 − x O4 thin films with varying Ni amount (0 ≤ ≤ x ≤ ≤ 1.5) were deposited on MgO(001) via reactive molecular beam epitaxy. The growth process was monitored during film deposition by means of X-ray diffraction. All prepared films exhibit a well-ordered structure with complete vertical crystallinity throughout the whole film growth and flat surfaces of the final films independent of the Ni amount. An enhancement of the vertical compression in the initial growth continuously decreases up to a film thickness of 8 nm. During further growth, all films exhibit residual and constant vertical compression with lateral adaption of the final films to the substrate lattice, as observed by high energy surface X-ray diffraction experiments. Hard X-ray photoelectron spectroscopy measurements of the final films reveal increasing Fe3+ Fe 3 + :Fe2+ Fe 2 + ratios for higher Ni content and point to additional NiO agglomerations within the films exceeding the stoichiometric Ni amount of x = 1.

Journal Keywords: High-energy X rays; X-ray photoelectron spectroscopy; Epitaxy; Thin films; X-ray diffraction

Subject Areas: Physics, Materials

Instruments: I07-Surface & interface diffraction

Other Facilities: PETRA III