Physics

Dr. Nerea Sebastian Ugarteche

Dr. Nerea Sebastian’s research is focused on soft matter systems. She defended PhD in 2012 at the University of Basque Country (Spain), held a Humboldt Postdoctoral Fellowship in the Soft Matter Lab in Magdeburg (Germany) and came to the F7 department, Light & Matter group at IJS as a Marie Sklodowska Curie Fellow in 2016. Since then, she has been involved in the investigations of the recently discovered polar nematic liquid crystalline systems, both ferromagnetic and ferroelectric nematic materials.

Contact
Nerea
Research programme: Light and matter
Training topic: Physical properties of ferroelectric nematic liquid cristals

Nematic liquid crystals (NLCs) have been known for years and are broadly exploited in modern display technologies, constituting a multibillion business. The key aspect of their applicability is the unique combination of fluidity, anisotropic physical properties and processability. In thermotropic NLCs, elongated molecules do not show positional order, but on average orient along the same direction. At any moment, there are as many molecules pointing “up” as “down” along this direction and thus, the “standard” NLC state is uniaxial and non-polar. A polar counterpart, in which inversion symmetry is broken, was already envisioned more than a hundred years ago by M. Born, but it was not until 2017 that it was experimentally realized.

In the Light & Matter group, we have been involved since the beginning in the research on the materials exhibiting ferroelectric nematic (FNLC) phases, covering their discovery and seminal investigations for this emerging field. FNLCs have astonishing physical properties: spontaneous polarization values of the order of some solid ferroelectrics, giant apparent dielectric permittivity in the range of 10000 and large non-linear optical properties. The combination of such properties with the fluidity of the system is expected to result in a variety of novel physical phenomena, such as novel mechano-electric effects. The large exploitation potential of such effects in applications is currently hindered by the lack of fundamental understanding as no such studies have been performed so far. PhD candidate will join a very dynamic research field and carry out a comprehensive set of experimental investigations combining polarization optical microscopy, second harmonic generation microscopy and interferometry studies, optical transmission simulations, dielectric spectroscopy and material characterization techniques among others. The candidate will also be involved in the development of customized measurement setups.  

Our research on FNLCs is performed in collaboration with other international groups from UK, Germany, Belgium, Spain and China among others.

  1. N. Sebastián, M. Lovšin, B. Berteloot, N. Osterman, A. Petelin, R. J. Mandle, S. Aya, M. Huang, I. Drevenšek-Olenik, K. Neyts and A. Mertelj, Nat Commun, 2023, 14, 3029.
  2. P. M. Rupnik, L. Cmok, N. Sebastian and A. Mertelj, 2024. arXiv:2401.16272
  3. N. Sebastian, M. Čopič and A. Mertelj, (Invited to Perspectives series), Phys. Rev. E., 2022, 106, 021001-1-021001-27.
  4. R.J. Mande, N. Sebastian, J. Martinez-Perdiguero and A. Mertelj. Nat. Comm.. 2021, 12, 4962-1-4962-12.
  5. N. Sebastian, L. Cmok, R.J. Mandle, M.R. de la Fuente, I. Drevenšek-Olenik, M. Čopič and A. Mertelj. Phys. Rev. Lett., 2020, 124, 037801-1-037801-6, Featured as Editor’s suggestion and Featured in Physics Today.
  6. A. Mertelj, L. Cmok, N. Sebastián, R. J. Mandle, R. R. Parker, A. C. Whitwood, J. W. Goodby and M. Čopič. Phys. Rev. X, 2018, 8(4), 041025-1-041025-12. Featured in Physics Today.