Skyrmions in blue phases of chiral liquid crystals

Pišljar, Jaka (author), Marinčič, Matevž (author), Ghosh, Sharmistha (author), Turlapati, Srikanth (author), Rao, Nandiraju V. S. (author), Nych, Andriy (author), Škarabot, Miha (author), Mertelj, Alenka (author), Petelin, Andrej (author), Pusovnik, Anja (author), Ravnik, Miha (author), Muševič, Igor (author)

Using high-resolution microscope observations, we show that both the static cubic (BPI) and the dynamic amorphous (BPIII) blue phases consist of fractional skyrmion filaments that transform into the same quasi two-dimensional structure of ‘baby’ half-skyrmions upon confinement to ultra-thin layers. We confirm this using numerical simulations of BPIII skyrmion structures in confinement combined with optical simulations, which reproduce experimental images, shown to originate at the glass-sample boundaries. Chiral nature of skyrmion filaments is demonstrated through experimental observations and optical simulations using circularly polarised light of opposite handedness producing images that vary strongly in comparative optical contrast. Direct observations and light scattering measurements of BPIII dynamics in bulk reveal that it is a highly dynamic phase, distinguished by two well-separated dynamic regimes, the slower of which can be observed even with a naked eye. We show that the slow dynamics corresponds to the thermally driven collective reshaping of the amorphous structure, while the fast mode is due to the director fluctuations within the filaments. Chirality of the relaxation modes in the bulk isotropic phase is also demonstrated and discussed. We show the dynamics in thinnest layers still show a two phase behaviour, with overall dynamics of half-skyrmions dramatically slowed down.

• Language: English
• Keywords: liquid crystals, chiral nematics, blue phases, skyrmions, blue fog, fractional skyrmions, topological liquid
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 1406–1425
• Numbering: Vol. 50, no. 7/10
• PID: 20.500.12556/RUL-152842
• UDC: 538.9
• ISSN on article: 0267-8292
• DOI: 10.1080/02678292.2023.2188613
• COBISS.SI-ID: 147562243
• Publication date in RUL: 08.12.2023

Record is a part of a journal

• Title: Liquid crystals
• Shortened title: Liq. cryst.
• Publisher: Taylor & Francis
• ISSN: 0267-8292
• COBISS.SI-ID: 1690628

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: tekoči kristali, kiralni nematiki, modre faze, skirmioni