Quasi-2D Perovskite Oxide Membranes with a Twist – PerOMem

PerOMem focuses on the study of the fundamental, structural and electronic properties of quasi-2D perovskite oxide membranes, in the form of freestanding membranes and twisted heterostacks, which we will prepare by taking advantage of techniques that have been developed for 2D materials. We choose two representative perovskite oxides to explore two different types of physics in 1) nickelates, which exhibit an insulator-metal transition; 2) ferroelectrics, where the properties are governed by the ferroelectric polarisation. We will address the following questions: How does reducing the oxides’ thickness and modifying their mechanical and electrical boundary conditions affect the ferroelectric domain structure, insulator-metal transition and the symmetry of the material? Will potential interfacial phenomena, e.g. moiré patterns, lead to new properties? What is the effect of removing the constraints from the growth substrate on the membranes’ properties?

We will study new ways of driving transitions, i.e. strain, and study the effect of new degrees of freedom, e.g. twist angle, to achieve additional control of the materials’ properties.

While the final aim of this project is to build heterostacks of membranes and combine them with conventional 2D materials to exploit emerging properties, the main work focus is the study of fundamental properties of perovskite membranes and novel physical phenomena arising from the interaction between the layers.

In our project we combine a set of multidisciplinary skills from material growth to characterisation, including electrical and surface probe techniques to study the ferroelectric properties and insulator-to-metal transitions of the membranes as well as Raman spectroscopy and scattering scanning near field optical microscopy as function of temperature, strain and electric field.