Materials Colloquium 2021, March 10th

Straining films: a versatile design tool for ferroic materials

Kathrin Dörr (Martin Luther University Halle, Germany)

There is nearly no strain-free thin film on a substrate, and such films are a foundation of modern technologies. Therefore, it has been learned long ago how to exploit film stress / strain for designing electronic properties of common semiconductors. For ferroic (magnetic or ferroelectric) materials like oxides and polymers, strain can be an efficient design tool, too. However, many strain-driven phenomena are yet to be discovered and modelled, because these materials have a more complex structure and physics background. In this talk, recently established approaches to apply different kinds of film strain in ferroic materials are introduced. These include tip-induced nano-strain in force microscopy, electric strain control with piezoelectric substrates, “strain doping“ with helium atoms and “symmetry strain“ transfer at oxide interfaces. The usefulness of such tools for straining films will be shown in examples for controlling crystal symmetries, domain configurations, and switching times - or simply for measuring strain-dependent properties.

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