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SUMMARY:Polarization patterns of ferroelectric nematics - Oleg Lavrentovic
 h (Kent State University)
DTSTART:20250818T090000Z
DTEND:20250818T094500Z
UID:TALK234700@talks.cam.ac.uk
DESCRIPTION:A ferroelectric nematic liquid crystal is formed by achiral mo
 lecules with large dipole moments. Its orientational order is universally 
 described as unidirectionally polar\, which raises the question of how the
  structure avoids a strong depolarization field and splay deformations tha
 t bring about bound charges. We demonstrate a rich plethora of polarizatio
 n patterns in ferroelectric nematics not constrained by crystallographic a
 xes. Domain walls take on the shapes of conic sections\, separating circul
 ar vortices of polarization [1\,2]\nWhen a flat ferroelectric nematic slab
  is anchored only at one bounding plate\, its ground state becomes optical
 ly active\, with left- and right-hand twists of polarization\; the twists 
 occur in chemically achiral system [3]. Despite the increase in elastic en
 ergy of deformations and domain walls\, the twists reduce the electrostati
 c energy and weaken when the material is doped with ions [4].\nAn external
  electric field applied to create a splay produces structures in which the
  splay of one polarity is compensated by a splay of opposite polarity\, th
 us solving the electrostatic problem by geometrical means [5]. Finally\, a
  uniform pattern of electric polarization can be created by applying the e
 lectric field to the nematic [6] or isotropic [7] phase of the ferroelectr
 ic nematic material. The induced order causes a strong birefringence that 
 can be switched on and off within 100 ns\; the effect is promising for ele
 ctro-optical applications.\nThis work was supported by NSF grant DMR-23418
 30.\nReferences:\n[1]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; P. 
 Kumari\, B. Basnet\, H. Wang\, and O. D. Lavrentovich\, Nature Communicati
 ons 14\, 748 (2023).\n[2]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;
  P. Kumari\, O. Kurochkin\, V. G. Nazarenko\, O. D. Lavrentovich\, D. Golo
 vaty\, and P. Sternberg\, Physical Review Research 6\, 043207 (2024).\n[3]
 &nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; P. Kumari\, B. Basnet\, 
 M. O. Lavrentovich\, and O. D. Lavrentovich\, Science 383\, 1364 (2024).\n
 [4]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; M. O. Lavrentovich\, 
 P. Kumari\, and O. D. Lavrentovich\, ArXiv\, 2502.03747 (2025).\n[5]&nbsp\
 ;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; B. Basnet\, S. Paladugu\, O. K
 urochkin\, O. Buluy\, N. Aryasova\, V. G. Nazarenko\, S. V. Shiyanovskii\,
  and O. D. Lavrentovich\, Nature Communications 16\, 1444 (2025).\n[6]&nbs
 p\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; K. Thapa\, S. Paladugu\, and
  O. D. Lavrentovich\, Opt Express 32\, 541317 (2024).\n[7]&nbsp\;&nbsp\;&n
 bsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; K. Thapa\, S. Paladugu\, and O. D. Lavre
 ntovich\, Adv Opt Mater\, accepted (2025).
LOCATION:Seminar Room 1\, Newton Institute
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