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[Fizinfo] Szemináriumok - Seminars: Máthé Marcell Tibor

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  • From: Szeminárium koordinátor <sem-admin AT>
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  • Subject: [Fizinfo] Szemináriumok - Seminars: Máthé Marcell Tibor
  • Date: Thu, 22 Feb 2024 06:00:01 +0100 (CET)
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PhD házivédésMáthé Marcell TiborHUN-REN Wigner FK SZFIInstabilities and cross
effects in ferroelectric nematic liquid crystals2024. február 27. kedd,
10.00, KFKI Telephely, I. épület 1. emeleti TanácsteremExperimental
confirmation of the existence of the first three-dimensional liquid with
ferroelectric properties was achieved a few years ago. The ferroelectric
nematic liquid crystals exhibit huge spontaneous electric polarization while
keeping fluidity. The topic of the presented PhD work covers the discovered
cross-effects and electric field induced instabilities in polar nematics.The
unusual symmetry of the phase allowed the exploration of new cross effects in
ferroelectric liquids. I will present a thermo-hydrodynamical effect in
sessile droplets, where a temperature gradient can induce stable flow of the
material [1]. Furthermore, I will describe the presence of inverse
piezoelectricity (electric field induced mechanical vibration) in polar
nematic films [2].I will show interfacial instabilities in liquid bridges and
in sessile droplets in the presence of external electric fields [3]. The
primary instability called ramification induces the growth of stable branches
from the liquid leading to the formation of fractal-like structures. A
secondary instability resembles to the Rosensweig type labyrinthine
instability observed in ferrofluids and in dielectrics, nonetheless in our
case the required threshold field was orders of magnitude smaller. To
understand these instabilities, I conducted various experiments and
simulations using the finite element method. It has turned out that the
interfacial instabilities can cause droplet fragmentation, resulting in the
creation of distinct active particle-like objects called "febots". When
subjected to a specific voltage and frequency range, febots exhibit a high
degree of mobility, forming a new type of artificial self-propelled active
system. I will present the characteristic properties and the statistical
analysis of the febot motion.Finally, the filament forming ability of polar
nematics is discussed [4]. I will present how ferroelectric fluid fibres are
stabilised without and with the presence of an external electric field.
Additionally, new measurement techniques for determining physical parameters
of ferroelectric nematics, such as spontaneous electric polarization and
viscosity, are presented.References[1] M.T. Máthé, Á. Buka, A. Jákli, P.
Salamon, Ferroelectric nematic liquid crystal thermomotor, Physical Review E
105, L052701 (2022) DOI:[2] M.T.
Máthé, M.S.H. Himel, A. Adaka, J.T. Gleeson, S. Sprunt, P. Salamon, A. Jákli,
Liquid Piezoelectric Materials: Linear Electromechanical Effect in Fluid
Ferroelectric Nematic Liquid Crystals, Advanced Functional Materials, 2314158
(2024) DOI:[3] M.T. Máthé, B. Farkas,
L. Péter, Á. Buka, A. Jákli, P. Salamon, Electric field-induced interfacial
instability in a ferroelectric nematic liquid crystal, Scientific Reports 13,
6981 (2023) DOI: [4] M.T. Máthé,
K. Perera, Á. Buka, P. Salamon, A. Jákli, Fluid Ferroelectric Filaments,
Advanced Science 2305950 (2024) DOI:;Minden érdeklődőt szívesen
látunk! - Everyone is welcome to attend.Nagy Attilasem-admin AT

  • [Fizinfo] Szemináriumok - Seminars: Máthé Marcell Tibor, Szeminárium koordinátor, 02/22/2024

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