A funded PhD position (3years) on 3D topological shaping of liquid crystal is open at Laboratoire Ondes et matière d'Aquitaine, Bordeaux, France. The PhD is expected to start autumn 2021..

The coupling between light and matter in mesoscale systems, those with intrinsic length scales that are the same as the wavelength of the interrogating electromagnetic radiation, can be exceptionally strong and lead to intriguing novel phenomena. In this project we want to investigate a new route to create such a system based on liquid crystal topological structures.
While topological defects and solitons are universal features in condensed matter physics, liquid crystals are prime choice materials to investigate those concepts thanks to their molecular properties of long range orientational order. In the case of cholesteric liquid crystals, they present an helicoidal order. When the orientational order is constrained or frustrated, under an external stimulus, one can thus write a local information in the form of a spatially localized elastic excitation. This information is recordable and erasable at will. In our group, we are investigating the morphogenesis of such structures and their potential application in optics.
Despite the fact that the nature and topological diversity of these localized excitation have been recently revealed, the clear understanding of (external) field(s)-matter interactions allowing to generate them is lacking from a fundamental point of view and for their exploitation. So far, these structures are induced on-demand, one-by-one, by using a laser light beam. In contrast, in this experimental project, we aim to explore a new mechanism based on a photoelectric effect to write an arbitrary number of them simultaneously, while controlling their location over macroscopic area. To achieve this, we will use the so-called liquid-crystal light valve [2]. Concretely, the PhD student will explore the formation of non-trivial orientational liquid crystal structures (so-called topological solitons) trying to unravel the role of the intrinsic physical properties (mechanical, optical, electrical, thermal) of the chiral liquid crystal material. She/he will also explore the light-matter interaction with a particular focus on the Left/right symmetry breaking that one can anticipate from activated spin and orbital degree of freedom of the light on resonant optical reorientational process at the supramolecular scale.
Hence this work will provide qualitative and quantitative progress towards the state of the art and beyond the fundamental perspective will open applicative one. Indeed, the obtained topological structure will be exploited to develop new kind of reconfigurable LC device.

Funding available : We are looking for an experimental physicist eager to find out and with good communication skills to join our team. Knowledge or experience in soft matter and/or optics-photonics is a plus.

Please send us a CV with your academic record, your Master 1&2 grading report, a cover letter and the name of 2 referees. Applications are to be sent in French or English.

Contact:delphine.coursault@u-bordeaux.fr/ /etienne.brasselet@u-bordeaux.fr/

[www.loma.cnrs.fr]

[1] W. Haas, J. Adams, Appl.Phys. Lett. 25,263 (1974); M. Kawachi, O. Kogure, Y. Kato, Jpn. J. Appl. Phys. 13, 1457 (1974).
[2] S. Pirkl, P. Ribiere, and P. Oswald, Liq. Cryst. (1993), 13, 413-425.
[3] C. Loussert and E.Brasselet, Applied Physics Letters 104, 051911 (2014); C. Loussert, S. Iamsaard, N. Katsonis, and E. Brasselet, Adv. Mater. 26, 4242 (2014); T. Orlova, F. Lancia, C. Loussert, S. Iamsaard, N. Katsonis and E. Brasselet, Nature Nanotech 13, 304-308 (2018).
[4] I. I. Smalyukh, Y. Lansac, N. A. Clark, and R. P.Trivedi, Nature Mater. 9, 139 (2010); P. J. Ackerman and I. I. Smalyukh, Phys.