Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 55: Multiferroic Oxide Thin Films and Heterostructures I (joint session KFM/TT/MA)

TT 55.10: Vortrag

Mittwoch, 14. März 2018, 12:15–12:30, EMH 225

Continuous control of morphotropic phases by strain doping — •Andreas Herklotz¹, Stefania Florina Rus², Er-Jia Guo³, Kathrin Dörr¹, and Thomas Zac Ward³ — ¹Martin-Luther-Universität Halle-Wittenberg, Halle, Germany — ²National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Romania — ³Oak Ridge National Laboratory, Oak Ridge, USA

The realization of a strain-driven morphotropic phase boundary in epitaxial BiFeO₃ (BFO) films has broadened this definition to single-phase materials and opened up great potential for advanced applications. However, a greater success of morphotropic systems in thin film technologies would require a ex situ control of the thin film’s composition or strain state that is practically impossible with standard epitaxy approaches. Here we demonstrate that ex situ strain doping via low-energy helium implantation induces a complete phase transition from epitaxial rhombohedral-like to supertetragonal BFO films. This control over morphotropic phases is highly tunable and fully reversible via a high temperature anneal. We argue that strain doping of morphotropic films creates a new phase space based on internal and external lattice stress that can be seen as an analogue to temperature-composition phase diagrams of classical morphotropic ferroelectric systems.

This effort was wholly supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division, with user projects supported at ORNLs Center for Nanophase Materials Research (CNMS).