Ferroic Domain Dynamics by In-Situ Transmission Electron Microscopy Techniques

Ferroic materials are routinely being used as key components for a wide variety of devices, such as sensors and actuators, and are particularly promising for devices such as memories and resistors. Ferroics' key characteristics are the development of equivalent ground states, known as domains that form to minimise the system's free energy. In general, domains appear after the material undergoes a ferroic phase transition, which have their origins in structural shear (ferroelastics), or electrical dipole moments (ferroelectrics). The reversible switching of domains is what ultimately enables ferroics' functionality.

All domains are physically separated by domain walls (DWs) which can have dimensions in the nanoscale regime. It has been shown that these interfaces exhibit novel properties, and are the active element in the ferroic material (instead of the bulk itself), making them especially attractive for nano-electronics. This, along the current trend on device miniaturisation, has brought a new area of research focused on domain engineering, where the functional properties of ferroics can be tuned by modifying the geometry, strain or electrical landscape. Examples of technologies that could directly benefit from a more comprehensive understanding and control over domains and domain boundaries are memory devices and optical and sonar detectors.

The aims of this project are two-fold, a) to obtain a deeper understanding of domain dynamics in ferroelastic domains at the micro and nanoscale as a function of applying external stimuli (temperature and strain) and b) to create novel configurations that will allow deterministic control of the ferroelastic domains (injection and subsequent motion). The latter will involve the creation of device-like structures, where strain will be introduced via biasing of a piezoelectric layer. The piezoelectric material will transfer the necessary strain to the ferroelastic sample for domain motion.

A substantial part of this project involves the development of sample preparation techniques, especially by Focused ion beam. The project will use in-situ TEM heating and biasing carried out in combination with other microscopy techniques such as atomic force microscopy to image and probe domain motion.

This project and its aims, represent a unique opportunity to study fundamental aspects of ferroelastic domains, along with device-like samples that will provide a different insight for future devices, in particular, for electronic applications.

Areas considered relevant to the project;

- Materials Characterisation

- Condensed Matter Physics