Linking Stoichiometry, Chemical Pressure, and Domain Structure in the van der Waals Ferrielectric CuInP2S6
4 affiliations
- 1HUN-REN Wigner Research Centre for Physics, Konkoly-Thege Miklós út 29-33, 1121 Budapest, Hungary
- 2Institute of Physics, University of Pécs, Ifjúság útja. 6, 7624 Pécs, Hungary
- 3Department of Atomic Physics, Institute of Physics, Budapest University of Technology and Economics, Műegyetem rkp. 3, 1111 Budapest, Hungary
- 4Department of the Physics of Semiconductors, Uzhhorod National University, 54 Voloshina Str., 88000 Uzhhorod, Ukraine
Abstract
The ferrielectric properties of layered CuInP2S6 (CIPS) are highly sensitive to stoichiometry and growth-induced defects. Here we systematically compare crystals grown by chemical vapor transport and the Bridgman–Stockbarger method with Cu- and In-enriched samples, combining compositional analysis, dielectric spectroscopy, uniaxial-pressure measurements, Raman spectroscopy, piezoresponse force microscopy and first-principles calculations. The transition temperature increases systematically from 307 K (Bridgman) to 312 K (Cu-enriched), 317 K (gas transport) and 322 K (In-enriched). In enrichment is consistent with spontaneous CIPS/In4/3P2S6 phase segregation that generates effective positive chemical pressure, stabilizing the ferrielectric state and producing a strongly biased, pinned domain configuration. Cu enrichment produces the opposite response—lower TC, enhanced dielectric loss and a fragmented domain morphology—characteristic of a negative-pressure-like perturbation of the Cu-ion energy landscape. Landau–Ginzburg–Devonshire analysis and density functional calculations provide a unified microscopic picture based on Cu-ion configurational freedom and interlayer coupling. Growth defects act as an independent source of domain-wall pinning. Together, these results establish stoichiometry and synthesis conditions as practical tools for engineering ferrielectric order in van der Waals CIPS.
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BibTeX
@article{gal2026linking,
title = {{Linking Stoichiometry, Chemical Pressure, and Domain Structure in the van der Waals Ferrielectric CuInP2S6}},
author = {Dávid Gál and Sándor Lenk and István Rigó and Miklós Veres and László Péter and Anton Kohutych and Konstantin Glukhov and Nyomó Dominika and Alexander Molnar},
journal = {Nanomaterials},
year = {2026},
month = oct,
doi = {10.3390/nano16211336},
url = {https://www.mdpi.com/2079-4991/16/21/1336},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Linking Stoichiometry, Chemical Pressure, and Domain Structure in the van der Waals Ferrielectric CuInP2S6
AU - Dávid Gál
AU - Sándor Lenk
AU - István Rigó
AU - Miklós Veres
AU - László Péter
AU - Anton Kohutych
AU - Konstantin Glukhov
AU - Nyomó Dominika
AU - Alexander Molnar
PY - 2026
DA - 2026/10/22
JO - Nanomaterials
DO - 10.3390/nano16211336
UR - https://www.mdpi.com/2079-4991/16/21/1336
AB - The ferrielectric properties of layered CuInP2S6 (CIPS) are highly sensitive to stoichiometry and growth-induced defects. Here we systematically compare crystals grown by chemical vapor transport and the Bridgman–Stockbarger method with Cu- and In-enriched samples, combining compositional analysis, dielectric spectroscopy, uniaxial-pressure measurements, Raman spectroscopy, piezoresponse force microscopy and first-principles calculations. The transition temperature increases systematically from 307 K (Bridgman) to 312 K (Cu-enriched), 317 K (gas transport) and 322 K (In-enriched). In enrichment is consistent with spontaneous CIPS/In4/3P2S6 phase segregation that generates effective positive chemical pressure, stabilizing the ferrielectric state and producing a strongly biased, pinned domain configuration. Cu enrichment produces the opposite response—lower TC, enhanced dielectric loss and a fragmented domain morphology—characteristic of a negative-pressure-like perturbation of the Cu-ion energy landscape. Landau–Ginzburg–Devonshire analysis and density functional calculations provide a unified microscopic picture based on Cu-ion configurational freedom and interlayer coupling. Growth defects act as an independent source of domain-wall pinning. Together, these results establish stoichiometry and synthesis conditions as practical tools for engineering ferrielectric order in van der Waals CIPS.
SN - 2079-4991
ER -