PhD Theses

Congratulations Dr. Matteo Springolo, new ICMAB graduate!

Congratulations Dr. Matteo Springolo for successfully defending your PhD Thesis "Flexoelectricity in two-dimensional materials from density-functional perturbation theory" at ICMAB! If you want to know more about Matteo, read below!

Why did you choose the ICMAB?

Because I found a very interesting project I was interested in.

How would you explain your research to a non-scientific audience?

My research concerns the study of how the distribution of the electronic charges in a thin layer changes when the material is bent.

What are the main applications of your research? Could you give us an example?

The main applications regards the generation of devices that can be used in nanoscale technology, like sensors, actuators, ecc.

What will you miss the most from ICMAB?

The professional and at the same time familiar environment.

How do you think this experience will contribute to your training and to your future?

I think it will give me the tools for facing the possible difficulties and challenges that one encounters when doing research.

What do you wish you had known at the beginning of your PhD?

I wish I had known better how to handle my time, in order to be more productive.

Why did you become a scientist? Which have been your role models?

Because I was enthusiastic about knowing more about physics. My role models were my professors.

Which is your favourite female scientist?

Margherita Hack

Thank you Matteo, and congratulations!

THESIS TITLE: Flexoelectricity in two-dimensional materials from density-functional perturbation theory

Matteo Springolo, Materials Simulation & Theory (MTS)

Date: Tuesday, 9 Apr 2024
Time: 12:00 PM
Venue: Institut de Ciència de Materials de Barcelona (ICMAB, CSIC) - Sala d'Actes Carles Miravitlles

Abstract:

Flexoelectricity, whereby an electrical response is induced by a strain-gradient (e.g. bending) deformation, is expected to play a prominent role in two-dimensional crystals due to their extreme flexibility, thus boosting the potential application of this class of materials in flexible, foldable, and wearable nanoscale devices. However, the progress towards a quantitative understanding of the flexoelectric effect in two-dimensional crystals has been thwarted by the lack of a reliable theoretical framework to interpret the available experimental data. In this thesis, we address this limitation by, first, establishing a first-principles theory and an efficient computational implementation of flexoelectricity in two-dimensional crystals and, second, by using the calculated coefficients to produce reliable models of the state-of-the-art experiments. Our approach is applied to study the out-of-plane and in-plane electrical response in several prototypical systems (graphene, boron nitride, transition-metal dichalcogenides, etc...). The in-plane response, active in a broad class of trigonal crystals, is shown to develop topologically nontrivial polarization textures in rippled and bent geometries, including vortices and antivortices, and spontaneously polarized tubes.

Supervisors:

Massimiliano Stengel
Miquel Royo

PhD Committee:

President: Riccardo Rurali, ICMAB, Spain
Secretary: Claudio Cazorla, UPC, Spain
Vocal: Roser Valentí, Goethe University, Germany

Oriol

24 April 2024