Online Ph.d.-forsvar af Daniele Torelli: Two-dimensional magnetic crystals from first principles

The defence will be carried out as an online video conference

Signing up as audience please contact Hugh Simons: husimo@fysik.dtu.dk

Supervisor

Associate Professor, Thomas Olsen, DTU Physics

Co-supervisor

Professor Karsten Wedel Jacobsen, DTU Physics
Senior Scientist, Niels Bech Christensen, DTU Physics

Evaluation Board

Professor Jakob Schiøtz, DTU Physics
Professor Joaquin Fernández-Rossier, International Iberian Nanotechnology Laboratory
Professor Oleg Yazyev, Ecole Polytechnique Federale de Lausanne

Chairperson

Assistant Professor, Hugh Simons, DTU Physics

Abstract

Magnetic and electrical effects are intrinsically entwined in electromagnetism, a fundamental force in our Universe.

For example, a charged particle like the electron, one of building block of matter, is equivalent to a tiny magnet and be represented as vector pointing in one direction.

When many electrons are arranged inside a crystal, magnetic patterns may emerge, like a parallel (ferromagnetism) or anti-parallel (anti-ferromagnetism) re-alignment of their vectors.

These quantum microscopic interactions are at the origin of extended samples’ magnetic proprieties. Some of them are very familiar – like the potential to bind to a metallic surface – others are less trivial – like magnetic levitation. Many applications, like novel data storage or logic devices are based on these mechanisms.  

A new ideal platform to explore the fundamental proprieties of materials and push the limit of miniaturization for tomorrow technologies, are two-dimensional (2D) materials, Since the isolation of graphene in 2004, 2D materials proved to be extraordinary versatile systems and a big effort has been directed toward the theoretical prediction and experimental synthesis of new 2D materials with novel functionalities.

However, magnetism in Flatland has always been a big challenge. Although decades of research, only in the past couple of years the first 2D magnetic monolayers have been confirmed to exist and be stable.

In most cases their feasibility depends crucially on the external environment. A major drawback is that above a critical temperature thermal fluctuations destroy the magnetic order and the system loses its magnetic proprieties.

In this thesis we explore the fundamentals mechanism of magnetism in 2D materials and using advanced first-principle methods, like Density Functional Theory and classical Monte Carlo simulations, we perform a systematic search of intrinsically ferromagnetic 2D materials with high critical temperature. We thus suggest a list of promising candidates for further investigation and benchmark our methods with available data in literature, which is found to be in good agreement with our predictions.

Tidspunkt

ons 08 apr 20
10:00

Arrangør

DTU Fysik

Kontaktperson

Hvor

Online forsvar
Kontakt Hugh Simons for deltagelse