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  • Letter
  • Open Access

Interpretation of dielectric spectroscopy measurements of ferroelectric nematic liquid crystals

Vojko Matko1, Ewa Gorecka2, Damian Pociecha2, Joanna Matraszek2, and Nataša Vaupotič3,4,*

  • *Contact author: natasa.vaupotic@um.si
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Phys. Rev. Research 6, L042017 – Published 18 October, 2024

DOI: https://doi.org/10.1103/PhysRevResearch.6.L042017

Abstract

The magnitude of the relative permittivity of the ferroelectric nematic phase (NF) has been the subject of lively scientific discussion since the phase was recently discovered. Dielectric spectroscopy measurements (DSMs) give a huge value of relative permittivity, which depends on the cell thickness, but this is argued to result from a misinterpretation of the DSM results. We have conducted DSM using a set of cells differing in thickness of the NF layer, type of electrodes, and presence/absence of nanoscale-thick surface polymer layers. To model the DSM results, cells are presented by an equivalent electric circuit that includes a capacitor due to the NF layer with frequency dependent complex relative permittivity, capacitors due to surface layers, and a resistor describing the limited conductivity of electrodes. DSM results for different cells with the same liquid crystal in the NF phase are semiquantitatively reproduced by the same set of physical parameters if a huge relative permittivity of the NF, which is even orders of magnitude larger than the measured apparent values, is assumed. We show that the capacitance of surface layers should also be considered in cells with no polymer alignment layer on the electrodes.

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References (33)

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Phys. Rev. Research 6, L042017– Published 18 October, 2024
  • Received 7 February 2024
  • Accepted 26 September 2024
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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