Binary mixtures of hard colloids self-assemble into a 3D icosahedral quasicrystal under certain conditions. This breakthrough, very recently discovered by the Soft Condensed Matter group in Utrecht (by both simulations and experiments: 10.1038/s41567-020-1003-9), suggests a way forward for the creation of photonic quasicrystals. Due to their non-periodic structure and exotic symmetries, quasicrystals - when created from particles of the right size and refractive index - are very promising candidates for materials that strongly manipulate visible light via band gaps. Such materials are relevant to fundamental studies and for a wide range of applications, from spontaneous emission control, via sensing, to lighting, lasers, photonic circuitry, photo-catalysis and structural colors.

A team of 5 PhD students from 4 groups at Utrecht University and Twente University will work together to achieve, for the first time, the self-assembly of photonic colloidal icosahedral quasicrystals as well as the associated periodic MgCu2 Laves phase crystals. The 5 PhD students will tackle many different aspects of this problem. Below we describe the plans for the 3 PhD students who will be hosted at Utrecht University.

PhD student I (Utrecht University, Soft Condensed Matter Group, Supervisor: Alfons van Blaaderen)
Real-Space Analysis of Binary 3D (Quasi)Crystal Nucleation and Growth

This project will experimental work to in order to i) analyse the 3D binary nucleation and growth of 3D icosahedral quasi- and periodic binary crystals in slowly drying index matched emulsion droplets, ii) the growth and analysis of MgCu2 crystals from mixtures of tetramers and spheres in 3D on the single particle level, and iii) the growth of photonic 3D icosahedral quasicrystalline supraparticles and MgCu2 photonic crystals using high index core-shell particles.

Useful skills: Previous experience with soft matter science (like colloid synthesis and/or self-assembly).

PhD student II (Utrecht Univeristy, Soft Condensed Matter Group, Supervisor: Laura Filion)
Predicting Binary 3D (Quasi) Crystal Nucleation and Growth

This project will involve theoretical and simulations work in order to i) develop order parameters for studying binary (quasi)crystals, ii) to examine the interplay between local fluid structure and crystallization in binary hard-sphere mixtures with multiple competing (quasi) crystalline phases, both in bulk and confinement and iii) to identify the optimal conditions for the nucleation of targeted (quasi) crystalline phases.

Useful skills: Background in theoretical or computational physics, some experience with writing simulation and analysis codes.

PhD student III: (Utrecht University, Nanophotonics Group, Supervisor: Allard Mosk) Interfacing light to photonic quasicrystals by wavefront shaping

This project will involve experimental work in order to i) construct an instrument to probe scattering states of spherical photonic (quasi)crystals, ii) Probe and optimize the photonic interaction strength of photonic quasicrystals, working closely with other PhD students in this programme and identify and study scattering states near the band edge and defect states in quasicrystals.

Useful skills: Optical lab skills, python programming and interfacing, teamwork, physics or related background including coursework in electrodynamics, quantum mechanics and condensed matter physics.

This project has received funding from the NWO within the ENW NWO-Groot programme.

We are looking for highly motivated and creative PhD candidates who have:

• a Master's degree or an international equivalent in the relevant fields of Physics, Chemistry and/or Materials Science;
• research experience within the fields of soft matter, (nano)photonics, nano and/or colloid science, the specific background will depend on the position in question (see project descriptions for more background);
• excellent research and scientific writing skills;
• perseverance and an independent, pro-active working style;
• the willingness to look beyond the borders of his or her own discipline and a strong motivation to work in a multidisciplinary team;
• excellent collaboration and communication skills (written and verbally) in English.

• a full-time position for 4 years;
• participation in the education programme of the Graduate School of Natural Sciences;
• access to a network of collaborative researchers within the Debye Institute;
• a full-time gross salary that starts at €2,395 and increases to €3,061 per month (scale P of the Collective Labour Agreement Dutch Universities (cao));
• benefits including 8% holiday bonus and 8.3% end-of-year bonus;
• a Pension scheme, partially paid parental leave, and flexible employment conditions based on the Collective Labour Agreement Dutch Universities.

In addition to the employment conditions laid down in the CAO for Dutch Universities, Utrecht University has a number of its own arrangements. For example, there are agreements on professional development, leave arrangements and sports. We also give you the opportunity to expand your terms of employment yourself via the Employment Conditions Selection Model. This is how we like to encourage you to continue to grow.

More information about working at the Faculty of Science can be found here.

Utrecht University’s Debye Institute for Nanomaterials Science brings together six research groups from the departments of Chemistry and Physics. The central research theme is 'Nanomaterials for Sustainability', supported by three strong, interconnected research pillars: catalysis, colloids and nanophotonics.

At the Faculty of Science there are 6 departments to make a fundamental connection with: Biology, Chemistry, Information and Computing Sciences, Mathematics, Pharmaceutical Sciences and Physics. Each of these is made up of distinct institutes which work together to focus on answering some of humanity’s most pressing problems. More fundamental still are the individual research groups – the building blocks of our ambitious scientific projects.

Utrecht University is a friendly and ambitious university at the heart of an ancient city. We love to welcome new scientists to our city – a thriving cultural hub that is consistently rated as one of the world’s happiest cities. We are renowned for our innovative interdisciplinary research and our emphasis on inspirational research and excellent education. We are equally well-known for our familiar atmosphere and the can-do mentality of our people. This lively and inspiring academic environment attracts professors, researchers and PhD candidates from all over the globe, making both the University and the Faculty of Science a vibrant international community and wonderfully diverse.