Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 44: Focus Session: Surfaces and Interfaces of (Incipient) Ferroelectrics (joint session O/KFM)

O 44.2: Topical Talk

Wednesday, September 7, 2022, 15:30–16:00, H3

Optimisation and miniaturisation of naturally-layered multiferroic thin films — •Lynette Keeney — Tyndall National Institute, University College Cork, Lee Maltings Complex, Dyke Parade, Cork, Ireland, T12 R5CP

Multiferroic materials, possessing simultaneous ferroelectric and ferromagnetic memory states, are road-mapped as promising multistate architectures for memory scaling beyond current technologies. In recent years, my team reported the design of such a novel room temperature multiferroic material with an Aurivillius phase structure that could ideally be suited to future fabrication of revolutionary memory devices.

In this presentation, I will discuss how electrostatic strain and elastic energy variations close to bismuth oxide interfaces and defect regions are key to promoting magnetic cation partitioning and multiferroic behaviour. These also influence the formation of exotic charged domain walls and polar vortices, further initiating technology prospects in ultra-compact data storage.

As miniaturisation of electronic devices continues, a crucial requirement is the enhancement of their functional properties at very small dimensions. Direct liquid injection chemical vapour deposition allows for frontier-development of ultra-thin films at fundamental thickness. Via a two-dimensional layer-by-layer growth mode, films equating to half of one unit-cell (2.5 nm) of the Aurivillius structure are grown. The persistence of stable ferroelectricity, even when pushed to ultra-thin thicknesses, demonstrates the recent progress in the optimisation of Aurivillius phase materials for utilisation in future miniaturised multiferroic-based devices.