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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Polarization patterns of ferroelectric nematics - 
 Oleg Lavrentovich (Kent State University)
DTSTART;TZID=Europe/London:20250818T100000
DTEND;TZID=Europe/London:20250818T104500
UID:TALK234700AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/234700
DESCRIPTION:A ferroelectric nematic liquid crystal is formed b
 y achiral molecules with large dipole moments. Its
  orientational order is universally described as u
 nidirectionally polar\, which raises the question 
 of how the structure avoids a strong depolarizatio
 n field and splay deformations that bring about bo
 und charges. We demonstrate a rich plethora of pol
 arization patterns in ferroelectric nematics not c
 onstrained by crystallographic axes. Domain walls 
 take on the shapes of conic sections\, separating 
 circular vortices of polarization [1\,2]\nWhen a f
 lat ferroelectric nematic slab is anchored only at
  one bounding plate\, its ground state becomes opt
 ically active\, with left- and right-hand twists o
 f polarization\; the twists occur in chemically ac
 hiral system [3]. Despite the increase in elastic 
 energy of deformations and domain walls\, the twis
 ts reduce the electrostatic 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\, thus
  solving the electrostatic problem by geometrical 
 means [5]. Finally\, a uniform pattern of electric
  polarization can be created by applying the elect
 ric field to the nematic [6] or isotropic [7] phas
 e of the ferroelectric nematic material. The induc
 ed order causes a strong birefringence that can be
  switched on and off within 100 ns\; the effect is
  promising for electro-optical applications.\nThis
  work was supported by NSF grant DMR-2341830.\nRef
 erences:\n[1]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&n
 bsp\;&nbsp\; P. Kumari\, B. Basnet\, H. Wang\, and
  O. D. Lavrentovich\, Nature Communications 14\, 7
 48 (2023).\n[2]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;
 &nbsp\;&nbsp\; P. Kumari\, O. Kurochkin\, V. G. Na
 zarenko\, O. D. Lavrentovich\, D. Golovaty\, and P
 . Sternberg\, Physical Review Research 6\, 043207 
 (2024).\n[3]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nb
 sp\;&nbsp\; P. Kumari\, B. Basnet\, M. O. Lavrento
 vich\, and O. D. Lavrentovich\, Science 383\, 1364
  (2024).\n[4]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&n
 bsp\;&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. Kurochkin\, O. Bulu
 y\, N. Aryasova\, V. G. Nazarenko\, S. V. Shiyanov
 skii\, and O. D. Lavrentovich\, Nature Communicati
 ons 16\, 1444 (2025).\n[6]&nbsp\;&nbsp\;&nbsp\;&nb
 sp\;&nbsp\;&nbsp\;&nbsp\; K. Thapa\, S. Paladugu\,
  and O. D. Lavrentovich\, Opt Express 32\, 541317 
 (2024).\n[7]&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nb
 sp\;&nbsp\; K. Thapa\, S. Paladugu\, and O. D. Lav
 rentovich\, Adv Opt Mater\, accepted (2025).
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:
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