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Two ERC Grants for Leiden Physics

This year, two Leiden physicists have earned a prestigious ERC Starting Grant. With a budget of 1.5 million euros, this is one of the largest individual grants for scientists.

Micro particles

Daniela Kraft receives her ERC grant for research on the behavior of so-called colloids—particles of a millionth of a meter. They are found on the battlefield of the micro world, where a continuous storm rages of chaotically dancing molecules. Kraft uses this ceaseless motion to her advantage by letting colloids form structures by themselves. During earlier research, she managed to generate a number of basic structures and to have multiple colloids shift and rotate similar to joints.

Now she wants to take it one step further and build larger flexible systems from those building blocks. Up until now, larger structures were always rigid—problematic if you want to build things like micro robots. The ERC grant gives her plenty of opportunity for this; she can appoint two PhD students and a postdoc. And there are indeed more than enough open questions, says Kraft. ‘We want to know the impact of a slightly different build-up of a system, for example with cubes instead of spheres. And we want control switching back and forth between various structures, e by using magnetic or active particles, for example.’

The ultimate goal on the horizon is to have micro robots that build themselves. ‘There are already robots at nano-scale,’ says Kraft. ‘And just last year the Nobel Prize was awarded for molecular robots. But in between there is nothing. We want to fill that gap.’

Artist's impression of building switchable structures by using colloidal hinges.

Quantum materials

Milan Allan is receiving his ERC grant for research on quantum materials. These show mysterious quantum mechanical effects on a macroscopic scale. Their electrons often behave in a collective way, similar to a swarm of birds, but guided by the magic of quantum mechanics. Still, we know very little about them. Understanding quantum materials is one of the holy grails in physics, and could have major technological advantages. As an example, in the past, the quantum mechanical properties of silicon led to the computing revolution after we started to understand them.

Allan scrutinizes quantum materials by looking at the ‘melting’ of electrons with an STM microscope. Physicists consider electrons in a material as an electronic liquid that can be frozen or molten. When molten, the liquid conducts electricity, but when frozen, it will block any currents. Certain materials have both frozen and molten parts in their electronic liquid. This interplay between molten and frozen is thought to define the exotic properties of quantum materials, including the property of being able to conduct electricity without resistance, which would benefit society tremendously.

With his ERC grant, Allan has the opportunity to build exactly the machinery needed to look at quantum materials one electron at a time. He will also use the money to hire two PhD students and two postdocs.

Artist's impression of the melting of electron spins. On the left, the electronic liquid is frozen and their spin are neatly ordered. On the right, the electronic liquid is molten and magnetic waves can flow through them.