An in-situ study of the growth kinetics of pulsed laser deposition of multiferroic complex oxides and its influence on the properties of magnetoelectric coupling

• Applicants: Professor Dr. Tilo Baumbach; Professorin Dr. Dagmar Gerthsen, since 1/2023
• Subject Area: Synthesis and Properties of Functional Materials ; Experimental Condensed Matter Physics
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 412136875

• Final Report Year: 2023

Final Report Abstract

The aim of the project was to gain a fundamental understanding of the crystal growth of multiferroic oxide films during their deposition by pulsed laser deposition (PLD). This should help finding out optimal growth parameters for the production of such material systems with specifically desired multiferroic properties in each case and to be able to tailor the films for selected applications. For this reason, the structural properties of different oxide films were experimentally determined as a function of the growth parameters and their influence on the magnetic and ferroelectric layer properties were investigated. The main task of the project was to follow in-situ the evolution of the crystalline structure of the multiferroic materials under investigation and their interfaces with the substrate or subsequent layers during growth by using state-of-the-art in-situ X-ray scattering methods for synchrotron radiation, in particular X-ray diffraction (XRD). In addition, the experimental XRD data were compared with numerical simulations so that statements on layer growth such as the lateral and vertical size of islands, the surface coverage and the coalescence of islands during layer formation could be determined. With regard to the latter issues, the project benefited from the expertise of the Prague group in the theory of X-ray scattering and applying it to model crystal growth and related phenomena. A comprehensive characterization of the structure and microchemistry of the grown layers was only possible by their subsequent ex-situ investigation using scanning probe microscopy and various techniques of scanning and transmission electron microscopy. The combination of these ex-situ characterization methods with in-situ XRD and the correlation of the findings thus obtained with electrical and magnetic measurements allowed a comprehensive description of PLD-grown multiferroic layers. The investigated systems include both homogeneous ferroelectric and ferromagnetic systems such as Ba0.5Sr0.5TiO3 (BSTO) on MgO substrate, LuFeO3 (LFO) with and without platinum interlayer on sapphire, BaFe12O19 (BaM) on Y-doped ZrO2 (YSZ), and multiferroic sandwich layers of YbFeO3 (YbFO) and BaFe12O19 (BaM), each deposited on YSZ. During the deposition of thin Pt interlayers, which are necessary for contacting the multiferroic material systems in electrical measurements, interfering phenomena such as dewetting and islanding were observed. For this reason, the PLD growth of pure platinum layers for different layer thicknesses was also investigated in detail to determine optimal parameters for the formation of continuous contact layers.

Publications

• Structure Quality of LuFeO3 Epitaxial Layers Grown by Pulsed-Laser Deposition on Sapphire/Pt. Materials, 13(1), 61.
  Bauer, Sondes; Rodrigues, Adriana; Horák, Lukáš; Jin, Xiaowei; Schneider, Reinhard; Baumbach, Tilo & Holý, Václav
  
• Combined In Situ XRD and Ex Situ TEM Studies of Thin Ba0.5Sr0.5TiO3 Films Grown by PLD on MgO. Crystal Research and Technology, 55(9).
  Bauer, Sondes; Rodrigues, Adriana; Jin, Xiaowei; Schneider, Reinhard; Müller, Erich; Gerthsen, Dagmar & Baumbach, Tilo
  
• In situ grazing-incidence x-ray scattering study of pulsed-laser deposition of Pt layers. Physical Review B, 102(12).
  Holý, V.; Bauer, S.; Rodrigues, A.; Horák, L.; Jin, X.; Schneider, R. & Baumbach, T.
  
• Analytical TEM study of thin PLD-grown LuFeO3 layers on Pt/sapphire substrates, poster presentation at the Microscopy Conference 2021 (MC2021) in Regensburg, August 22 to 26, 2021, proceedings MS8.P030, p. 289-290
  X. Jin; B. Nergis; A. Rodrigues; S. Bauer; L. Horák; T. Baumbach; V. Holý & R. Schneider
  
• Time-Resolved Morphology and Kinetic Studies of Pulsed Laser Deposition-Grown Pt Layers on Sapphire at Different Growth Temperatures by in Situ Grazing Incidence Small-Angle X-ray Scattering. Langmuir, 37(2), 734-749.
  Bauer, Sondes; Rodrigues, Adriana; Horák, Lukáš; Nergis, Berkin; Jin, Xiaowei; Schneider, Reinhard; Gröger, Roland; Baumbach, Tilo & Holý, Václav
  
• Effect of the laser fluence on the microstructure and the relating magnetic properties of BaFe12O19 films grown on YSZ(111) by PLD for optimized perpendicular recording, MML Materials Workshop: Energy, Engineering & Functional Materials in Julich, April 20 to 21, 2023
  B. Nergis; S. Bauer; X. Jin; K. Seemann; L. Horak; R. Schneider; V. Holy; S. Ulrich & T. Baumbach
  
• Effect of Underlayer Quality on Microstructure, Stoichiometry, and Magnetic Properties of Hexaferrite BaFe12O19 Grown on YSZ(111) by Pulsed Laser Deposition. Langmuir, 39(40), 14308-14327.
  Bauer, Sondes; Nergis, Berkin; Jin, Xiaowei; Schneider, Reinhard; Wang, Di; Kübel, Christian; Holy, Vaclav; Horak, Lukas; Seemann, Klaus; Ulrich, Sven & Baumbach, Tilo