Session S37: Top Science in Europe: Early Career Scientists and the ERC Grants

Atomically thin van der Waals magnets: a career in flatland

Layered magnetic materials are at the origin of modern magnetism and among the very first compounds to be explored at cryogenic temperatures. The phenomenon of magnetic ordering in layers has tantalized condensed matter physicists ever since the theory put forward by Mermin and Wagner demonstrating that long-range ordering in low dimensions is forbidden in an isotropic spin lattice. In order to confirm this hypothesis, many experiments have been performed in the aforementioned layered crystals as an approximation of a two-dimensional (2D) spin lattice. However, interlayer coupling in bulk systems is not negligible and an approach for the study of true 2D magnetism had been for a long time. With the avenue the 2D materials a genuine approach to correlated states in low-dimensions has been unlocked. In this talk I will narrate the launch of my independent reasearch carrier, which has been intimately tied to our discovery of the first free-standing 2D ferromagnet made out of a single layer of a ferromagnetic insulator: chromium triiodide. I will try to stimulate for risk taking and multidisciplinarity in condensed matter physics careers and provide insight into timely research opportunities.   

Electrocatalysis from two-dimensional materials: an ERC project

Electrochemical reactions can afford hydrogen gas (H2) and small organic molecules from water and CO2, respectively and therefore offers promise for the production of fuels. Owing to
their reduced dimensionality, two-dimensional (2D) materials have emerged as interesting
platforms for studying electrocatalysis1. In addition, their properties can largely be tuned by
changing their elemental composition, their thickness and their atomic structure.
In 2018, our activity received support from the European Research Council (ERC) for
exploring the influence of the defects, the crystal structure and the electronic properties on the
catalytic performance towards the reduction of CO2. By developing engineering strategies, our
group aims at investigating the electrocatalytic properties of 2D materials including transition
metal dichalcogenides and quasi-2D transition metals2,3. To do so, we have recently reported the
fabrication of electrochemical microcells using microfabrication techniques2. This device
architecture allows testing individual nanosheets in order to precisely quantify the activity from
the edges and the basal planes. In my talk, I will illustrate how the ERC grant was pivotal in
developing my research activities in Europe.
References:
1. Voiry, D., Shin, H. S., Loh, K. P. & Chhowalla, M. Low-dimensional catalysts for hydrogen
evolution and CO2 reduction. Nat. Rev. Chem. 2, 0105 (2018).
2. Voiry, D. et al. The role of electronic coupling between substrate and 2D MoS2 nanosheets in
electrocatalytic production of hydrogen. Nat. Mater. 15, 1003–1009 (2016).
3. Li, L. et al. Role of Sulfur Vacancies and Undercoordinated Mo Regions in MoS2 Nanosheets
toward the Evolution of Hydrogen. ACS Nano 13, 6824–6834 (2019).   

Obtaining an ERC Starting Grant

The European Research Council (ERC) is the continent's pre-eminent source of competitive funding to support investigator-driven frontier research across all fields. The ERC was designed by researchers and its funding decisions are made by disciplinary peers solely on the basis of scientific excellence. This 'bottom-up' approach allows the scientists themselves to identify new opportunities in any field of research, rather than being led by priorities set by politicians. Grants are awarded through open competition to projects headed by starting and established researchers who are working or moving to work in Europe.

In 2014, I discovered that the scattering of energetic electrons can cause silicon impurities to move through the graphene lattice, revealing a potential for atomically precise manipulation using the focused electron probe. To develop this into a practical technique, improvements in the description of beam-induced displacements, advances in heteroatom implantation, and a concerted effort towards the automation of manipulations were required in a multidisciplinary effort combining computational and experimental work in a custom-modified scanning transmission electron microscope electron microscope.

In this talk, I will describe my journey from designing a high-risk, high-reward frontier research project to writing a successful proposal and presenting it to my peers in a grant interview. After successfully receiving the grant and completing the grant negotiations, I started my project in October 2017. The generous support of 1.5 million euros over five years from an ERC Starting Grant allowed me to start my own research group devoted to this topic, and gave ample visibility within my university. This and the fact the grant is tied to my person and transferrable to another institution directly contributed to the tenure track position I received at the University of Vienna in 2019.   

PHYSICS FOR SOCIETY: GRAND CHALLENGES IN THE HORIZON 2050

The talk will provide an overview of the EPS action designed to address the social
dimension of science and the grand challenges in Physics that will bring radical
change to developed societies and to provide basic understanding of nature on the
Horizon 2050.

Although the quest for knowledge in itself is not necessarily susceptible to ethical
evaluation, science abandons its ethical neutrality when it addresses the way in which
knowledge is generated and when one considers the impact of its technological
applications on individuals and society. Some consequences of being science (as a
whole) a non-ethically neutral actor in Society will be addressed.

This action, developed within the framework of the EPS Forum Physics and Society,
should reach a broad audience that is willing to explore a future shaped by science. A
target audience is young people looking for perspectives in physics.   

Connecting the (Quantum) Dots: Road to ERC Funding

Colloidal semiconductor nanocrystals (commonly referred to as Quantum Dots) are one of the
earliest examples of Nanomaterials as their initial discovery dates back to 1986. Nevertheless, they
still attract considerable attention thanks to their versatile chemical synthesis, desirable properties
for optoelectronics and rich photophysics. Since 2013, my research effort has been dedicated to the
development of optoelectronic devices based on colloidal semiconductor nanocrystals.
Nanocrystals based II-VI semiconductors have served as a model system for understanding the
strong correlation between chemical synthesis and physical properties, as well as the development
of technological applications such as solar cells, lasers and light-emitting diodes (LEDs). Such
knowledge is employed nowadays for the development of the newly discovered lead-based
perovskites (general formula: APbX3, where A = Cs or an organic moiety and X = Cl, Br or I).

In this talk, I will present some recent results on NC light-emitting diodes (LEDs) based on PbS and
perovskite nanocrystals, operating both in the visible and in the infrared spectral range. The
efficiency of NC-LEDs has now reach important milestones thanks to interdisciplinary collaboration
between physicists, chemists and material scientists. Yet, LEDs based on ensemble of nanocrystals
(i.e. nanocrystal films) show good performance in terms of efficiency and luminance but their
applicability is still limited to standard consumer electronics products such as displays and
illumination.

The future challenge is to exploit colloidal semiconductor nanocrystals for single-photon generation
under electrical excitation, thus leading to a novel class of non-classical light sources. In this
playground, the ERC has provided me support through a starting grant. In the last part of my talk I
will describe how “connecting the dots” between different research fields has led me to a successful
grant application.